Engineering Chemistry Volume 10

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Volume 10 of
Engineering Chemistry

ISSN print 2813-6527
ISSN web 2813-6535

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Table of Contents

Characterization of Dislocations in 4H-SiC

Hong Yu Peng, Can Zhu, Chao Gao

Zwitterionic Buffering Agent as an Alternative to Improve Carboxylic Acid Extraction Performance with 1-Heptanol Solvent

Saidah Altway, Serli Dwi Rahayu, Andi Setyo Beki, Suprihatin Suprihatin, Shinta Amelia Putri

Efficiency of Industrial-Scale Biogas Application from Palm Oil Mill Effluent (POME) as a Renewable Energy Source: A Case Study at PT AMP

Leni Marlina, Ardinal Ardinal, Kasma Iswari, Salmariza Sy, Doni Putra

Synthesis of Pour Point Depressant from Black Soldier Fly Maggot Oil

Nila Tanyela Berghuis, Jihan Asma Halifah, Muhammad Yahya Lubis, Astra Agus Pramana

The Potential of Fly Ash Based Geopolymer Coatings for Steel Corrosion Protection

Sarini Mat Yaakob, Suriati Sufian, Nurul Ekmi Rabat

Effect of Additional Concentration of ATMP Inhibitor on The Formation of 40% Phosphoric Acid Scale

Daril Ridho Zuchrillah, Lily Pudjiastuti, Fatima Az Zahra, Hilmy Dzaky Edo Pratama, Indah Asmaul Chusna, Aulia Zalsabila

Keywords Index

Authors Index

The original version of this eBook is available on https://www.scientific.net/book/engineering-chemistry-vol-10/978-3-0364-1889-6

Engineering Chemistry, ISSN: 2813-6535, Vol. 10, pp 1-9

doi: 10.4028/p-XZR8jn

© 2025 The Author(s). Published by Trans Tech Publications Ltd, Switzerland.

Submitted:
2025-01-04

Revised:
2025-03-19

Accepted:
2025-03-28

Online:
2025-08-26

Characterization of Dislocations in 4H-SiC

The original version of this paper is available on https://www.scientific.net/EC.10.1.pdf

Hongyu Peng , Can Zhu and Chao Gao

SICC, No. 99 South Tian Yue Road, Jinan, China, 250118

penghongyu@sicc.cc, zhucan@sicc.cc, gaochao@sicc.cc

Keywords: Silicon Carbide; Threading Screw Dislocation; Basal Plane Dislocation; Non-destructive Characterization; KOH Etching; X-ray Topography

Abstract

Accurate characterization of dislocations is crucial for optimizing the performance of SiCbased power devices. The traditional way to measure dislocation density in SiC industry is KOH etching, a destructive approach that makes the wafer no longer available for epitaxial growth. Another major limitation of this technique is the accuracy of the data since some dislocations can be hardly recognized. For example, the etch pit of threading screw dislocation is similar to that of threading edge dislocation, both of which are usually in hexagonal shape while the primary difference is the size. However, those challenges and limitations in KOH etching do not exist in X-ray topography. In this paper, the non-destructive approach, X-ray topography, is introduced to characterize dislocations in 4 H -SiC industry. Threading screw dislocations were measured by both KOH etching and X-ray topography, the result of which indicates that some threading screw dislocations clearly visible in Xray topograph are not recognizable in KOH etching image. In addition, some prismatic dislocations not recognized in KOH etching image can be observed in X-ray topographs. Moreover, unlike destructive KOH etching, wafers measured by X-ray topography can be further used for annealing, epitaxial growth, ion implantation and etc., which is beneficial to SiC fundamental research.

Introduction

The original version of this paper is available on https://www.scientific.net/EC.10.1.pdf

4H-SiC has been widely used in power devices because of its superior physical properties compared to silicon [1, 2]. In recent years, substrate suppliers have made a lot of progress in preparing wafers with large diameter and low dislocation density [3,4]. Nevertheless, defects still cannot be completely removed even using the latest growth techniques. These defects such as dislocations can deleteriously influence the performance of devices and even cause failures [5, 6]. Therefore, an accurate way to characterize dislocations is in demand.
The traditional way to measure dislocation density in SiC industry is using KOH etching [7], where the dislocations intersecting wafer surface are revealed as etch pits. Based on the size and shape of the etch pits, threading edge dislocations (TEDs), threading screw dislocations (TSDs) and basal plane dislocations (BPDs) are recognized. However, there are some limitations of this method. Because it is destructive, the etched wafers are no longer available for epitaxial growth, resulting in additional waste of materials, which makes it more difficult to reduce the price of wafers. More importantly, recognizing TSDs and BPDs by KOH etching is not very accurate. For example, it is usually difficult to distinguish between TSD and TED despite the etch pits of TSD is bigger than that of TED, causing underestimation of TSD density [8]. When the angle between basal plane dislocation line and sample surface is small (i.e. the line direction of BPD is close to [1-100]), the etch pit of BPD dramatically changes, making it hard to recognize it. Inaccurate TSD and BPD density measurements brings more difficulty to find correlations between dislocation and die yield or device performance.
In this paper, we introduce X-ray topography (XRT) to characterize TSDs and BPDs in 4 H -SiC industry. Compared to KOH etching, XRT is non-destructive, wafers after measurements can be further used. The comparison between KOH etching and XRT is shown in Table 1. The fundamentals and functions of the equipment has been previously reported [9-11]. A. Soukhojak et. al. has
mentioned to use XRT in SiC industry, but the scanning speed of XRT is low [12]. With recent release from Fraunhofer IISB, the scanning time for BPD measurement is reduced to 5 minutes, making it possible to apply XRT to mass production.

Table 1 Comparison between KOH Etching and XRT

| KOH Etching | XRT
Wafer reusability | No | Yes
TSD accuracy | Low | High
BPD accuracy | High | High
Workflows | Complicated | Simple
| 1.Heating | 1.Image Recording
| 2.Etching | 2.Dislocation recognition
| 3.Wafer Cleaning |
| 4.Image Recording |
| 5.Dislocation Recognition |

Experiment

The original version of this paper is available on https://www.scientific.net/EC.10.1.pdf

The samples used in this study are commercially available 6-inch and 8-inch N-type 4H-SiC wafers with off-cut towards 11-20 grown by physical vapor transport (PVT) method. The typical growth temperature is around . The Nitrogen doping concentration of the wafer is in the mid range. KOH etching method and X-ray topography were used to characterize dislocations in the samples. KOH with additives were heated to a temperature around , wafers placed in a Nickel bracket were then etched for 10 minutes in molten KOH [7]. After KOH etching, optical microscope was used to record images of the etch pits on the surface of the wafer. Rigaku XRTmicron was used to take X-ray topographic images. 0008 reflection topograph and 11-20 transmission topograph were recorded using and radiation respectively. High resolution topographic images were recorded by a charge-coupled device (CCD) with a resolution of 5.4 pixel. The applied scanning speed is . 11-20 topographs used for BPD density measurement were recorded by Hypix 3000, where the scanning time is about 5 minutes for 6-inch wafers. Software 'Topography' developed by Rigaku was used to measure TSD density, while BPD density was estimated by XRT toolbox.

Results and Discussion

The original version of this paper is available on https://www.scientific.net/EC.10.1.pdf

TSD Measurement. As mentioned before, TSD density measured by KOH etching can be less accurate since the etch pits of TSD can be similar to that of TED. Fig. 1 shows the image of dislocations in the same region revealed by KOH etching (Fig. 1 (a)) and 0008 X-ray topograph (Fig. 1 (b)). TSDs or threading mixed dislocations (TMDs) are shown as dark dots in X-ray 0008 topograph (Fig. 1 (b)), as marked by the boxes. However, only the ones marked by yellow boxes show relatively big hexagonal etch pits in Fig. 1 (a), which distinguishes TSDs from TEDs. The other ones marked by red boxes do not show obviously big etch pits, making them mixed together with TEDs, thus causing it difficult to distinguish them from TEDs. Therefore, the TSD density measured by KOH etching is usually underestimated.

Fig. 1. KOH etching image (a) and 0008 X -ray topograph (b) of the same region on the same wafer Si-face. Dislocations marked by yellow boxes in X-ray topograph can be recognized as TSDs in KOH etching image, while the ones marked by red boxes in X-ray topograph can be hardly recognized as TSDs in KOH etching image since they are similar to nearby TEDs.

Fig. 1. KOH etching image (a) and 0008 X -ray topograph (b) of the same region on the same wafer Si-face. Dislocations marked by yellow boxes in X-ray topograph can be recognized as TSDs in KOH etching image, while the ones marked by red boxes in X-ray topograph can be hardly recognized as TSDs in KOH etching image since they are similar to nearby TEDs.

In addition, KOH etching results usually vary from etching conditions or even crystal growth conditions. It has been reported that the etch pits size of dislocations increases linearly with the increase of mass ratio of additives [13]. Other effects such as etching time, wafer doping concentration or doping type are also reported to influence the shape and size of the etch pits [14]. In this study, different conditions were applied to two sister wafers. Prior to KOH etching, wafer in Fig. 2(a) was pre-processed at high temperature. The TSD revelation of these two wafers after KOH etching turns out to be quite different. As shown in Fig. 2, low angle grain boundaries on the left side of the image can be regarded as a reference point. TSDs marked by yellow boxes are revealed in both wafers as the etch pits are obviously bigger than those of TEDs. However, TSDs marked in red boxes in Fig. 2 (a) are not recognizable in Fig. 2 (b). Similarly, some TSDs in Fig. 2 (b) are not recognizable in Fig. 2 (a) either. This result indicates that TSD density and distributions measured by different KOH etching recipes can be significantly different, a more accurate and consistent method is in demand.

Fig. 2. KOH etching image of two sister wafers right next to each other ((a) & (b)). Two different etching conditions were applied to these two wafers. Etch pits marked by yellow boxes are TSDs revealed in both wafers, while the etch pits marked by red boxes are bigger only in left image.

Fig. 2. KOH etching image of two sister wafers right next to each other ((a) & (b)). Two different etching conditions were applied to these two wafers. Etch pits marked by yellow boxes are TSDs revealed in both wafers, while the etch pits marked by red boxes are bigger only in left image.

Compared to KOH etching, X-ray topography is a more stable and consistent approach to characterize TSDs. Since and , where is the normal of the diffraction plane, is the Burgers vector of the dislocation, and is dislocation line direction, TEDs (the Burgers vector is while line direction is along c axis) is out of contrast in X-ray 0008 reflection, identification of TSDs is thus not to be confused with TEDs in XRT [15, 16]. The consistency of XRT is evaluated by measuring sister wafers from the same boule. Since TSDs are growth dislocations that are inherited from the seed crystal and grow along 0001 direction, their density should not vary significantly from the first wafer on the seed side to the last wafer on the dome side. Although some TSDs can be converted to Frank dislocations during growth [17], the converted ones are usually a small fraction of all the TSDs, so the TSD density of the wafers from the same boule should be almost the same. Fig. 3 shows the TSD density of the wafers from the same boule measured by XRT. In order to eliminate the error caused by chance, three boules were measured. The measured TSD density does not change significantly for the same boule, indicating the stability and consistency of the data recorded by XRT. Moreover, the repeatability and reproducibility of XRT are evaluated by measuring the same wafer for multiple times. As shown in Fig. 4, TSD density almost stays the same under different measurements (the error is less than ), indicating good stability and repeatability of this characterization method.

Fig. 3. TSD density of the wafers from the same boule measured by XRT. Wafer 1 to 7 is from the same boule, where wafer 1 is close to the seed side while wafer 7 is close to the dome side.

Fig. 3. TSD density of the wafers from the same boule measured by XRT. Wafer 1 to 7 is from the same boule, where wafer 1 is close to the seed side while wafer 7 is close to the dome side.

Fig. 4. Evaluation of XRT repeatability and reproducibility. TSD density of three wafers measured by XRT for 7 times.

Fig. 4. Evaluation of XRT repeatability and reproducibility. TSD density of three wafers measured by XRT for 7 times.

BPD measurement. In offcut , BPDs are usually revealed as shell-shape etch pits in KOH etching. However, that is not always the case. When BPD is almost parallel to direction (BPD 1 in Fig. 5 (a)), the angle between dislocation line and wafer surface is about , and the etch pit of BPD can be easily recognized. But if BPD is close to direction (BPD 2 in Fig. 5 (a)), this angle is close to zero, resulting in unrecognizable etch pit. In real case, the line direction of BPD is random, once the angle between BPD line direction and wafer surface is reduced to 1 or , the recognition of BPD etch pits turns to be difficult as their shape changes dramatically, resulting in underestimation of BPD density. As shown in Fig. 5 (b), BPDs marked by red boxes are recognizable, where the etch pit is like a shell. However, the BPDs marked by yellow arrows are not recognizable since the etch pit is like a needle, quite different from other standard BPD etch pits. Those ones are most likely prismatic dislocations based on their line directions and distributions ( is the angle between dislocation line direction and [11-20]) [18].

Fig. 5. (a) A diagram showing BPDs with different line directions. (b) KOH etching image of 4 H SiC, where BPDs are marked by red boxes, while the yellow arrow marked BPDs are not recognized.

Fig. 5. (a) A diagram showing BPDs with different line directions. (b) KOH etching image of 4 H SiC, where BPDs are marked by red boxes, while the yellow arrow marked BPDs are not recognized.

Fig. 6. KOH etching map (a), 11-20 X-ray topograph (b) and corresponding density map (c) of BPDs of the same wafer.

Fig. 6. KOH etching map (a), 11-20 X-ray topograph (b) and corresponding density map (c) of BPDs of the same wafer.

Since some of the BPDs (specifically prismatic dislocations) can be hardly recognized in KOH etching, the dislocation density can be underestimated and the distributions can be inaccurate. Fig. 6 (a) is a KOH etching map of BPDs in a typical 6-inch wafer, where the density is very low at the position of and 12 o'clock, and the overall BPD density is . However, as shown in 11 20 X-ray topograph (Fig. 6 (b)), there are many prismatic dislocations in those four regions. Fig. 6 (c) is the BPD density map estimated from XRT, where the density in those four regions is higher compared to that estimated from KOH etching and the overall BPD density is . The omission of some prismatic dislocations in KOH etching leads to the underestimation of BPD density, and that is also one of the reasons why a specific BPD distribution (higher BPD density at 4 corners) is usually obtained in KOH etching map.

Fig. 7. 11-20 X-ray topograph of the same wafer before (a) and after (b) annealing.

Fig. 7. 11-20 X-ray topograph of the same wafer before (a) and after (b) annealing.

Non-destructive. In addition to being able to measure dislocation density with high accuracy, XRT is also non-destructive, which not only saves wafers, but also has advantages in many other aspects. For example, the wafer can be imaged before some processes such as annealing, epitaxial growth and ion implantation. After those processes, the same wafer can be imaged again by XRT, therefore, dislocation behaviors during these processes can be investigated. Fig. 7 (a) & (b) are 11-20 X-ray topographs of 4 H -SiC wafer before and after annealing. As marked by the dashed red curves, some BPDs get straighten after annealing to minimize line tension, indicating that some energies stored in the wafer could be released during annealing process. Some BPDs marked by dashed yellow curves moves during annealing and could not be observed in its original position after the process.

Summary

The original version of this paper is available on https://www.scientific.net/EC.10.1.pdf

Characterization of TSD and BPD has been discussed in this paper. The density of both TSD and BPD can be underestimated in traditional KOH etching since some etch pits of TSDs are similar to that of TEDs, and some etch pits of prismatic dislocations can be hardly recognized. Moreover, KOH etching results are sensitive to etching conditions, same wafer could show different dislocation etch pits under different etching recipes. Since KOH etching is destructive, etched wafers are no longer available for epitaxial growth. But these limitations in KOH etching do not exist in X-ray topography. TSD is not to be confused with TED in XRT because of criteria and prismatic dislocations can be simply revealed by XRT. And XRT has good repeatability and reproducibility. As XRT is non-destructive, the measured wafers can be further used for annealing, epitaxial growth, ion implantation and etc. Therefore, we propose to apply XRT in SiC industry to replace traditional KOH etching, from which wafers can be saved, helping to reduce substrate cost. More importantly, accurate dislocation data generated by XRT helps to correlate substrate defects with epitaxial defects and device performance, providing important information for figuring out root causes of epitaxial defects or device failures.

Acknowledgement

The original version of this paper is available on https://www.scientific.net/EC.10.1.pdf

This work is supported by Shanghai Magnolia Talent Plan Pujiang Project under project No. 24PJD103

References

The original version of this paper is available on https://www.scientific.net/EC.10.1.pdf

T. Kimoto and J. A. Cooper, Fundamentals of Silicon Carbide Technology, (Wiley IEEE press, Singapore, 2014)

T. Kimoto, Prog. Bulk and epitaxial growth of silicon carbide, Cryst. Growth Charact. Mater. 62 (2016) 329-351.

A. R. Powell, J. J. Sumakeris, Y. Khlebnikov, M. J. Paisley, R. T. Leonard, E. Deyneka, S. Gangwal, J. Ambati, V. Tsevtkov, J. Seaman, A. McClure, C. Horton, O. Kramarenko, V. Sakhalkar, M. O'Loughlin, A. A. Burk, J. Q. Guo, M. Dudley, E. Balkas, Bulk growth of large area SiC crystals. Mater. Sci. Forum, 858 (2016) 5-10.

X. L. Yang, Y. N. Pan, C. Gao, Q. R. Liang, L. P. Wang, J. Y. Zhang, Y. H. Gao, X. X. Ning, H. Y. Zhang, Development of high quality 8 inch 4H-SiC substrates, Solid State Phenom., 344 (2023) 41-46.

P. J Wellmann, Review of SiC crystal growth technology, Semicond. Sci. Technol. 33 (2018) 103001

J. Huang, T. Chen, J. Lee, C. Huang, L. Hong. A perspective on leakage current induced by threading dislocations in 4H-SiC Schottky barrier diodes, Mater. Lett., 310 (2022) 131506

Y. Z. Yao, Y. Ishikawa, Y. Sugawara, H. Saitoh1, K. Danno1, H. Suzuki1, Y. Kawai1, and N. Shibata, Molten KOH etching with additive for dislocation revelation in epilayers and substrates, Jpn. J. Appl. Phys. 50 (2011) 075502

Y. Z. Yao, Y. Ishikawa, Y. Sugawara, K. Sato, K. Danno, H. Suzuki, T. Bessho, S. Yamaguchi, K. Nishikawa, J. Cryst. Growth, 364 (2013) 7-10.

K. Omote, Crystal defects in SiC wafers and a new X-ray topography system, The Rigaku Journal, 29(1) (2013) 1-8.

C. Reimann, C. Kranert, Non-destructive characterization of crystallographic defects of SiC substrates using X-ray topography for R&D and quality assurance in production, The Rigaku Journal, 37(2) (2021) 33-37.

K. Inaba, Defect structure analysis in single crystal substrates using XRTmicron, Rigaku Journal, 36(2) (2020) 11-18.

A. Soukhojak, T. Stannard, I. Manning, C. Lee, G. Chung, M. Gave, E. Sanchez, Measurement of Dislocation Density in SiC Wafers Using Production XRT, Mater. Sci. Forum, 162, (2022) 304-308

S. Sun, H. Song, J. Yang, H. Qu, W. Wang, J. Jian, The etching behaviour of dislocations in Ndoped 4H-SiC substrate, J. Cryst. Growth, 618 (2023) 1227318

L. Dong, L. Zheng, X. Liu, F. Zhang, G. Yan, X. Li, G. Sun, Z. Wang, Defect revelation and evaluation of 4 H Silicon Carbide by optimized molten KOH etching method. Mater. Sci. Forum, 740-742 (2013) 243-246

B. Raghothamachar, M. Dudley, G. Dhanaraj, X-ray topography techniques for defect characterization of crystals, in: G. Dhanaraj, K. Byrappa, V. Prasad & M. Dudley (Eds.) Springer Handbook of Crystal Growth, Springer Handbooks. Springer, Berlin, Heidelberg. 2010, pp. 1425-1451

H. Peng, T. Ailihumaer, F. Fujie, Z. Chen, B. Raghothamachar, M. Dudley, Influence of surface relaxation on the contrast of threading edge dislocations in synchrotron X-ray topographs under the condition of and , J. Appl. Cryst., 54 (2021) 439-443.

S. Hu, Y. Liu, Q. Cheng, Z. Chen, X. Tong, B. Raghothamachar, M. Dudley, Investigation of defect formation at the early stage of PVT-grown 4H-SiC crystals, J. Cryst. Growth, 628 (2024) 127542

J. Guo, Y. Yang, B. Raghothamachar, J. Kim, M. Dudley, G. Chung, E. Sanchez, J. Quast, I. Manning, Prismatic slip in PVT-grown 4H-SiC crystals, J. Electron. Mater. 464 (2017) 20402044

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The original version of this eBook is available on https://www.scientific.net/book/engineering-chemistry-vol-10/978-3-0364-1889-6

Engineering Chemistry, ISSN: 2813-6535, Vol. 10, pp 11-18

doi: 10.4028/p-Y4mTQO

© 2025 The Author(s). Published by Trans Tech Publications Ltd, Switzerland.

Submitted:
2024-03-05

Revised:
2025-01-16

Accepted:
2025-02-05

Online:
2025-08-26

Zwitterionic Buffering Agent as an Alternative to Improve Carboxylic Acid Extraction Performance with 1-Heptanol Solvent

The original version of this paper is available on https://www.scientific.net/EC.10.11.pdf

Saidah Altway , Serli Dwi Rahayu , Andi Setyo Bekti , Suprihatin Suprihatin and Shinta Amelia Putri

¹Department of Industrial Chemical Engineering, Sepuluh Nopember Institute of Technology, Kampus ITS, Keputih, Sukolilo, Surabaya 60111, Indonesia

Department of Chemical Engineering, Sepuluh Nopember Institute of Technology, Kampus ITS, Keputih, Sukolilo, Surabaya 60111, Indonesia

saidahaltway@chem-eng.its.ac.id, rahayuserli0100@gmail.com, suprihatin1041@gmail.com, shintaameliaputri27@gmail.com

Keywords: Carboxylic acids, liquid-liquid extraction, EPPS biological buffer

Abstract

Separation of carboxylic acids by liquid-liquid extraction method using 1-heptanol solvent and the addition of EPPS biological buffer was studied in this research. Liquid-liquid equilibrium (LLE) data on carboxylic acid systems (butyric acid/propionic acid), water, 1- heptanol, biological buffer EPPS at 303.15 K and atmospheric pressure were obtained. Experimental data were correlated well using the NRTL model with the RMSD below . Based on experimental data, the effect of adding EPPS biological buffer can increase extraction performance as indicated by the value of separation factor ( S ) of butyric acid increasing two times higher, while separation factor values of propionic acid can be increased 4 times higher than the system without EPPS biological buffer. These results can be used as a reference for the design of the extraction column in the carboxylic acid extraction process so that the extraction process can run more efficiently and optimally.

Introduction

The original version of this paper is available on https://www.scientific.net/EC.10.11.pdf

Carboxylic acid is an organic compound often used in various industries [1], such as propionic and butyric acid [2]. Propionic/butyric acid have main roles in the food and beverage industry as additives and preservative products. In addition, this carboxylic acid has a special role in the pharmaceutical industry as the main compound for producing medicines, including aspirin and phenacetin, which is very prospective in industrial development [3]. This carboxylic acid (propionic/butyric acid) is usually obtained by chemical reaction or fermentation. In the fermentation process, the carboxylic acid (propionic/butyric acid) produced usually has a low yield. It contains impurities such as high water content (aqueous solution) [4]. Thus, it is necessary to recover, concentrate, and purify carboxylic acid (propionic/butyric acid) from its aqueous solutions [5].

Several methods are used to separate solutes from aqueous solutions, including adsorption, membrane separation, distillation, and extraction [6]; however, each has limitations that reduce their efficiency. A significant challenge is achieving high recovery rates from dilute solutions. For instance, adsorption often shows low selectivity and capacity in complex mixtures, leading to incomplete recovery of target acids [7,8]. Traditional liquid-liquid extraction requires large amounts of organic solvents, raising operational costs and environmental concerns. While membrane techniques are promising, they face fouling and scaling issues that decrease effectiveness and lifespan [9]. Moreover, distillation tends to be ineffective for carboxylic acids due to their higher boiling points and azeotropes complicating the process [7,9]. Research indicates that liquid-liquid extraction (LLE) is more effective for recovering carboxylic acids from aqueous solutions than traditional techniques such as distillation, adsorption, and membrane separation. For instance, Karp et al. [10] reported that using trioctylamine dissolved in a hydrophobic alcohol significantly enhanced the extraction of propionic acid and acetic acid from fermentation broth. This method can improve recovery rates and minimize the loss of valuable acids during extraction [11].

The addition of salt, known as the "salting-out" effect, has been shown to enhance the extraction performance of carboxylic acids in liquid-liquid extraction. Vakili-Nezhaad et al., [12] demonstrated that introducing sodium chloride and potassium chloride into the aqueous phase significantly increased the separation factor for acetic and propionic acids when using isopropyl methyl ketone and isobutyl methyl ketone as the organic solvent. This improvement occurs because salt reduces the solubility of carboxylic acids in the aqueous phase, promoting their transfer to the organic phase. Similarly, Wannachod et al.[13] reported that incorporating salt altered the solubility and tie-line data for formic acid in liquid-liquid extraction systems, improving extraction performance. However, it is important to note that salt is often used in high concentrations, which can affect the optimal pH of the extraction medium, potentially denature biomolecules, and damage equipment. On the other hand, biological buffers, particularly EPPS (4-(2-hydroxyethyl)-1-piperazine propane sulfonic acid), is a zwitterionic sulfonic acid buffering agent that has the potential as a green agent for removing carboxylic acids from its aqueous solutions. It contains a piperazine ring that buffers and maintains pH within 7.3-8.7 [14]. Tiwikrama and Altway found that buffers could maintain a consistent pH , which is crucial for the stability of carboxylic acids during extraction [15] .The buffering capacity helps prevent unwanted side reactions at extreme pH levels, thus preserving the integrity of the extracted acids. Biological buffers can provide a more controlled extraction environment, reducing the risk of degradation of sensitive compounds [16].

This research will be carried out on the liquid-liquid extraction of carboxylic acids (propionic butyric acid) from an aqueous solution using 1-heptanol. 1-heptanol is a protic compound that has the potential to be an effective solvent in separating carboxylic acids from water because it is polar and has low vapor. Apart from that, the addition of EPPS biological buffer can improve extraction performance, as indicated by the separation factor and distribution coefficient values. The equilibrium data, organic and raffinate composition obtained will be correlated using Aspen Plus V12 to obtain NRTL model parameters to present a new system for the recovery and purification process of carboxylic acids (propionic/butyric acid) with 1-heptanol solvent and the addition of EPSS biological buffer. Liquid-liquid equilibrium data and model parameters in this system can be used as a reference in designing columns for separating carboxylic acids from aqueous solutions in the chemical industry.

Materials and Methods

The original version of this paper is available on https://www.scientific.net/EC.10.11.pdf

Materials. Butyric acid ( %mass), propionic acid ( %mass), 4-(2-hydroxyethyl)-1piperazine propane sulfonic acid (EPPS) ( mass), 1-heptanol ( mass), were purchased from Merck Sigma-Aldrich Reagent Pte, Singapore.

Methods. In this research, liquid-liquid equilibrium measurements were conducted for a system consisting of carboxylic acids (propionic and butyric acid), water, 1-heptanol, and the biological buffer EPPS, using a jacketed equilibrium cell maintained at 303.15 K . Different concentrations of carboxylic acids (ranging from to mass) were dissolved in water. Following that, 1 -heptanol and the biological buffer EPPS were added according to specific calculations. The solution was stirred for four hours until it became homogeneous, after which a settling phase was allowed to occur for an additional four hours, resulting in the formation of two distinct phases: an acid-rich phase and a waterrich phase.

To maintain the temperature within the equilibrium cell, thermostatic water from a water bath was circulated. Samples from both the acid-rich and water-rich phases were collected and analyzed. Their compositions were analyzed using Gas Chromatography (GC, SCION 436-GC) equipped with a flame ionization detector (FID) and a SCION-5 capillary column to detect propionic acid, butyric acid, and 1-heptanol. Hydrogen was used as the carrier gas at a flow rate of . The oven temperature was set at for 10 minutes, then raised to at a ramp rate of . Both the injector and detector temperatures were maintained at . Each sample was analyzed three times, and the average value was used to calculate mass fractions. The water composition was studied using Karl Fischer, while the composition of EPPS was analyzed gravimetrically. The resulting equilibrium data were then correlated using the NRTL model and further simulated with Aspen Plus software.

Result and Discussion

The original version of this paper is available on https://www.scientific.net/EC.10.11.pdf

Liquid-liquid Equilibrium of Experimental Data. In this research, the liquid-liquid equilibrium measurement of carboxylic acid (propionic/butyric acid) + water + 1-heptanol + EPPS biological buffer with the independent variable, the composition of butyric acid and propionic acid each by mass, and with temperature 303.15 K and under atmospheric pressure ( 101.3 kPa ) as dependent variables. Obtained liquid-liquid equilibrium experimental data are presented in Table 1. The symbols , and represent the mass fraction of carboxylic acid, water, EPPS biological buffer, and solvent. Meanwhile, superscript I represents the organic phase, and superscript II represents the aqueous phase.

Table 1. Liquid-Liquid Equilibrium of Experimental Data for Carboxylic Acid (1) + Water (2) + EPPS (3) + Solvent (4) System at 303.15 K and 101.3 kPa

SYSTEM | ORGANIC PHASE | AQUEOUS PHASE
W₁I | W₂I | W₃I | W₄I | W₁II | W₂II | W₃II | W₄II
Butyric Acid + Water + EPPS + 1-Heptanol | 0.0036 | 0.0285 | 0.0000 | 0.9679 | 0.0006 | 0.7648 | 0.2340 | 0.0006
| 0.0190 | 0.0219 | 0.0000 | 0.9591 | 0.0044 | 0.7287 | 0.2661 | 0.0008
| 0.0727 | 0.0408 | 0.0000 | 0.8865 | 0.0136 | 0.7183 | 0.2672 | 0.0008
| 0.1593 | 0.0702 | 0.0000 | 0.7705 | 0.0292 | 0.7406 | 0.2296 | 0.0006
Propionic Acid + Water + EPPS + 1-Heptanol | 0.0676 | 0.0272 | 0.0000 | 0.9053 | 0.0180 | 0.7594 | 0.2211 | 0.0015
| 0.0801 | 0.0382 | 0.0000 | 0.8816 | 0.0230 | 0.7230 | 0.2520 | 0.0020
| 0.0891 | 0.0410 | 0.0000 | 0.8699 | 0.0270 | 0.7104 | 0.2600 | 0.0026
| 0.0920 | 0.0437 | 0.0000 | 0.8642 | 0.0370 | 0.6303 | 0.3300 | 0.0027

The addition of EPPS biological buffer in this research aimed to improve the extraction performance of carboxylic acid (butyric acid/propionic acid) + water + 1-heptanol. The mechanism by which a biological buffer promotes phase separation is similar to that of salt, which is called the buffering-out effect. The EPPS biological buffer utilized in this work is zwitterionic amino acid that can exhibit both positive and negative charges inside the same molecule, resulting in a net charge of zero for the complex ion. Furthermore, zwitterions, similar to electrolytes, possess substantial dipole moments and engage in electrostatic interactions with solvents and other charged molecules in the solution [17]. Biological buffer in water exhibits a substantial dipole owing to its zwitterionic characteristics, and it possesses both hydrogen bond donor and acceptor sites. Consequently, it is posited that the biological buffer significantly interacts with water molecules through mechanisms such as hydrogen bonding and electrostatic interactions, compelling the solute molecules to be separated from the aqueous solution into another liquid phase.

Based on the results in this study, the excellent extraction performance is demonstrated by the high composition of carboxylic acid (propionic/butyric acid) in the organic phase. As seen in Table 1, the solvent composition (1-heptanol) in the aqueous phase ( ) and the water composition in the organic phase show minimal values, and , respectively. This value indicates that during the extraction process, minimal solvent loss occurs, which can save energy requirements in the product purification process and solvent recycling. Thus, the addition of biological buffer EPPS as an auxiliary material for the separation of butyric acid/propionic acid from aqueous solutions is very prospective because the electrostatic interaction and van der Waals interaction between EPPS and water is more significant than with solvent due to the zwitterion nature of the biological buffer which has a significant dipole moment [18,19].

Distribution Coefficient and Separation Factor. The separation factor ( S ) represents the ability of 1-heptanol, with the addition of EPPS biological buffer as the solvent, to extract carboxylic acid (propionic/butyric acid) from its aqueous solution. A high separation factor value indicates satisfactory selectivity of a solvent and a buffering-out effect.

The distribution coefficient represents the capability of a solvent to carry the solute from its aqueous solution, where superscript I refers to the solvent phase, II refers to the aqueous phase, w1 stands for the mass fraction of water, and stands for that of carboxylic acid. Higher values of and the separation factor ( S ) would be desirable due to a lower required amount of solvent for separation and indicate satisfactory selectivity of a solvent and buffering-out effect [20]. The D and S calculation results from liquid-liquid equilibrium experimental data at 303.15 K and 101.3 kPa are presented in Table 2.

Table 2. Distribution Coefficient (Di) and Separation Factor (S) for Quaternary System at Temperature 303.15 K and 101.3 kPa

SYSTEM | WII | D₁ | D₂ | S
Butyric Acid + Water + EPPS + 1-Heptanol | 0.0006 | 6.57 | 0.037 | 176.6
0.0044 | 4.34 | 0.030 | 144.4
0.0136 | 5.33 | 0.057 | 93.8
0.0292 | 5.46 | 0.095 | 57.6
Propionic Acid + Water + EPPS + 1-Heptanol | 0.0180 | 3.75 | 0.036 | 104.8
0.0230 | 3.48 | 0.053 | 65.9
0.0270 | 3.30 | 0.058 | 57.2
0.0370 | 2.49 | 0.069 | 35.8

Based on the previous results, the highest separation factor values in the system (Butyric Acid/Propionic Acid) + Water + 1-heptanol were 98.65 and 25.96 at room temperature, respectively [21]. Thus, the separation factor values of butyric acid and propionic acid increased up to 1.6 times, and up to 4 times higher with the addition of EPPS biological buffer than the system without the addition of biological buffer. The increase in the separation factor value and distribution coefficient indicates the buffering-out effect of the biological buffer, i.e., the interaction of buffer ions with water molecules. This interaction reduces the solubility of propionic acid in the aqueous phase. This results in a buffering effect that transfers propionic acid to the organic solvent phase [12]. The separation factor values of butyric acid and propionic acid in the system with the addition of EPPS biological buffer respectively reached 57.6-176.6 and 35.8-104.8, as presented in Table 2. Meanwhile, the separation factor for butyric acid and propionic acid for systems without using biological buffer EPPS studied by (21) only obtained values of 40.7-96.8 and 7.6-25.8, respectively. The separation factor value with the EPPS biological buffer addition system is higher than without the addition of EPPS biological buffers. This shows that EPPS can increase the separation factor value in the system with the addition of biological buffers. In addition, EPPS biological buffers can improve and optimize the performance of the extraction column and prospective due to the buffering-out effect, creating an extraction process of butyric acid and propionic acid from an aqueous solution more efficient and selective [22]. The benefits of buffering-out compared to salting-out include a reduced risk of equipment corrosion and lower energy requirements for the recovery and recycling of extraction solvent. Subsequent to the extraction of butyric acid/propionic acid, the recovery of biological buffer can be utilized in the separation process. In general, the extraction of carboxylic acid without a biological buffer resulted in a decreased separation factor and distribution coefficient, necessitating increased energy and costs for subsequent product purification and extraction solvent recovery [21,23]. Consequently, the application of biological buffer presents a potential and competitive approach for the separation of carboxylic acid.

Correlation Results of the Non-Randomness Two-Liquid (NRTL) Model with Aspen Plus. The experimental data obtained were correlated using the Non-Randomness Two-Liquid (NRTL) equation, which can used to predict fractions and operating conditions, calculate equilibrium liquidliquid multicomponent composition, and be used in mixtures that form azeotropes such as carboxylic acids and water. The model can calculate the equilibrium composition of a multicomponent liquidliquid using only the constituent binary parameters. This model consists of the non-randomness parameter ( ) which can be used for mixtures with significant variations. The nonrandomness parameter with the NRTL model was set at 0.2 . The following is the NRTL model equation for multicomponent mixtures:

is the interaction parameter between molecules i and j , and is a non-randomness parameter representing the local composition. The non-randomness parameter ( ) is set to 0.2 for pair ( ).

Fig. 1. Phase Diagram of Butyric Acid + Water + EPPS + 1-Heptanol System; -m- experiment data, -- NRTL correlation data

Fig. 1. Phase Diagram of Butyric Acid + Water + EPPS + 1-Heptanol System; -m- experiment data, -- NRTL correlation data

Fig. 2. Phase Diagram of Propionic Acid + Water + EPPS + 1-heptanol; -m- experiment data, -- NRTL correlation data

Fig. 2. Phase Diagram of Propionic Acid + Water + EPPS + 1-heptanol; -m- experiment data, -- NRTL correlation data

The correlation of the experimental data is based on the Root Mean Square Deviation (RMSD) value reference, which is the absolute deviation of the average composition between experimental data and calculation results using a model equation.

Table 3. Interaction parameters of the NRTL model for quaternary system Acid (1) + Water (2) + Biological Buffer (3) + Solvent (4) at and

SYSTEM | i-j | bij(K) | bji(K) | αij | %RMSD
Butyric Acid + Water + EPPS + 1-Heptanol | 1-4 | 928.355 | 1933.64 | 0.2 | 0.8340
2-4 | 3698.38 | 376.687 | 0.2
3-4 | -876.438 | 215.287 | 0.2
1-2 | -178.972 | -1308.09 | 0.2
1-3 | 1741.92 | -213.193 | 0.2
2-3 | -1.21304 | -1979.02 | 0.2
Propionic Acid + Water + EPPS + 1-Heptanol | 1-4 | -1374.78 | -8881.58 | 0.2 | 0.7332
2-4 | 2277.16 | 604.698 | 0.2
3-4 | 1127.02 | 9116.73 | 0.2
1-2 | -1044.24 | -8818.80 | 0.2
1-3 | -6099.75 | -7371.43 | 0.2
2-3 | -3128.74 | -2145.93 | 0.2

Based on Table 3, the RMSD value from the NRTL model obtained is for Butyric acid + Water + EPPS +1 -Heptanol system and for Propionic acid + Water + EPPS +1 Heptanol system. This value shows that the NRTL Model can correlate liquid-liquid equilibrium experimental data well by obtaining the RMSD value of less than . The smaller deviation value indicates that the model is appropriate for the experiment. Based on the ternary diagram shown in Figure 1 for the Butyric acid + Water + EPPS + 1-Heptanol system and Figure 2 for Propionic acid + Water + EPPS + 1-Heptanol system also indicates that the NRTL model is correlated with wellproven tie-line results correlation and adjacent experimental data.

Conclusions

The original version of this paper is available on https://www.scientific.net/EC.10.11.pdf

In this work, the LLE data for carboxylic acid + water +1 -heptanol + EPPS biological buffer systems were measured in 303.2 and 101.3 KPa . The capability of 1-heptanol with the addition of EPPS biological buffer can extract butyric acid greater than that of propionic acid. This result indicates that the addition of EPPS biological buffer can improve the extraction performance of butyric acid and propionic acid with 1 -heptanol as the solvent, with the separation factor of butyric acid reaching 176.6, which shows an increase of 2 times higher compared to systems without EPPS biological buffers. Meanwhile, separation factor values of propionic acid can reach 104.8, which increases 4 times higher compared to a system without EPPS biological buffer. Experimental LLE tie-line data from the studied system were well correlated using the NRTL model with RMSD below . These results can be used as a reference for extraction column design in the carboxylic acid extraction process so that the extraction process can run more efficiently and optimally.

References

The original version of this paper is available on https://www.scientific.net/EC.10.11.pdf

Reyhanitash E, Brouwer T, Kersten SRA, van der Ham AGJ, Schuur B. Liquid-liquid extraction-based process concepts for recovery of carboxylic acids from aqueous streams evaluated for dilute streams. Chem Eng Res Des 2018;137:510-33. https://doi.org/10.1016/j.cherd.2018.07.038.

Djas M, Henczka M. Reactive extraction of carboxylic acids using organic solvents and supercritical fluids: A review. Sep Purif Technol 2018;201:106-19. .

Zidwick, M. J., Chen, J.-S., & Rogers P. Organic Acid and Solvent Production: Propionic and Butyric Acids and Ethanol. Prokaryotes Appl Bacteriol Biotechnol 2013;3.

Pandey S, Kamsonlian S, Chomal N, Kumar S. Theoretical and Experimental Studies on Extraction of Carboxylic Acids from Aqueous Solution Using Ionic Liquids. Int J Chem Eng Appl 2018;9:20-5. .

Roy S, Olokede O, Wu H, Holtzapple M. In-situ carboxylic acid separation from mixed-acid fermentation of cellulosic substrates in batch culture. Biomass and Bioenergy 2021;151:106165. .

Belova V V., Zakhodyaeva YA, Voshkin AA. Extraction of carboxylic acids with neutral extractants. Theor Found Chem Eng 2017;51:786-94. .

Datta D, Marti ME, Pal D, Kumar S. Equilibrium study on the extraction of levulinic acid from aqueous solution with aliquat 336 dissolved in different diluents: Solvent's polarity effect and column design. J Chem Eng Data 2017;62:3-10. .

Wever H De, Dennewald D. Screening of sorbents for recovery of succinic and itaconic acids from fermentation broths. J Chem Technol Biotechnol 2017;93:385-91. .

Lalikołlu M, Gök A, Gök MK, Aşçl YS. Investigation of Lactic Acid Separation by Layered Double Hydroxide: Equilibrium, Kinetics, and Thermodynamics. J Chem Eng Data 2015;60:3159-65. .

Karp EM, Cywar RM, Manker LP, Saboe PO, Nimlos CT, Salvachúa D, et al. PostFermentation Recovery of Biobased Carboxylic Acids. ACS Sustain Chem Eng 2018;6:1527383. .

Abdelhafiz M, Elbeih A, Naeim I. Liquid-Liquid Equilibria Study for a Common Azeotropic Ternary System. Jounal Enviroment Hazards 2020;4:1-6. .

Vakili-Nezhaad GR, Mohsen-Nia M, Taghikhani V, Behpoor M, Aghahosseini M. Salting-out effect of NaCl and KCl on the ternary LLE data for the systems of (water + propionic acid + isopropyl methyl ketone) and of (water + propionic acid + isobutyl methyl ketone). J Chem Thermodyn 2004;36:341-8. .

Wannachod T, Hronec M, Soták T, Fulajtárová K, Pancharoen U, Nootong K. Influence of salt on the solubility and tie-line data for water + formic acid + methyl isobutyl ketone at K. J Chem Eng Data 2016;61:2433-9. .

Taha M, Khoiroh I, Lee M. Phase Behavior and Molecular Dynamics Simulation Studies of New Aqueous Two-Phase Separation Systems Induced by HEPES Buffer. J Phys Chem B 2013;117:563-82.

Altway S, Ramli NB, Maulidia MI, Soeprijanto S, Zuchrillah DR, Tiwikrama AH. Computational study of the acetic acid extraction process from an aqueous solution with the aid of biological buffer. IOP Conf Ser Earth Environ Sci 2022;963:0-10. .

Altway S, Taha M, Lee MJ. Phase Separation of Alcohol (1-Propanol, 2-Propanol, or tertButanol) from Its Aqueous Solution in the Presence of Biological Buffer MOPS. J Chem Eng Data 2017;62:2509-15. .

Kirkwood JG. Theory of solutions of molecules containing widely separated charges with special application to zwitterions. J Chem Phys 1934;2:351-61. 1.1749489 .

Taha M, E Silva FA, Quental M V., Ventura SPM, Freire MG, Coutinho JAP. Good's buffers as a basis for developing self-buffering and biocompatible ionic liquids for biological research. Green Chem 2014;16:3149-59. .

Altway S, Tiwikrama AH, Rahayu SD, Zuchrillah DR, Soeprijanto S, Ramli NB, et al. LiquidLiquid Equilibria of Butyric Acid, Water, and Methyl Isobutyl Ketone with the Aid of Biological Buffer as a Green Auxiliary Agent. J Chem Eng Data 2023;68:1706-15. .

Wen G, Bai W, Zheng F, Reyes-Labarta JA, Ma Y, Wang Y, et al. Ternary liquid-liquid equilibrium of an azeotropic mixture (hexane + methanol) with different imidazolium-based ionic liquids at and 101.325 kPa . Fluid Phase Equilib 2018;461:51-6. .

Gilani AG, Gilani HG, Saadat SLS, Nasiri-Touli E, Peer M. Liquid-liquid equilibrium data in aqueous solutions of propionic and butyric acids with 1-heptanol at , 308.15, and 318.15) K. Korean J Chem Eng 2015;33:1408-15. .

Taha, Teng H, Lee M. The buffering-out effect and phase separation in aqueous solutions of EPPS buffer with 1-propanol, 2-propanol, or 2-methyl_2-propanol at . J Chem Thermodyn 2012.

Rodriguez LEG, Bail A, Castillo RO, Arízaga GGC. Removal and Extraction of Carboxylic Acids and Non-ionic Compounds with Simple Hydroxides and Layered Double Hydroxides. Curr Pharm Des 2019;26:650-63. .

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The original version of this eBook is available on https://www.scientific.net/book/engineering-chemistry-vol-10/978-3-0364-1889-6

Engineering Chemistry, ISSN: 2813-6535, Vol. 10, pp 19-24

doi: 10.4028/p-j5Nlbu

© 2025 The Author(s). Published by Trans Tech Publications Ltd, Switzerland.

Submitted:
2024-02-28

Revised:
2024-11-22

Accepted:
2025-01-15

Online:
2025-08-26

Efficiency of Industrial-Scale Biogas Application from Palm Oil Mill Effluent (POME) as a Renewable Energy Source: A Case Study at PT AMP

The original version of this paper is available on https://www.scientific.net/EC.10.19.pdf

Leni Marlina , Ardinal , Kasma Iswari , Salmariza Sy , Doni Putra

Research Center for Agroindustry, National Research and Innovation Agency, Indonesia-16911

Padang Industrial Services and Certification Center, JI. Raya LIK No. 23 Ulu Gadut Padang 25164, Indonesia

PT AMP Plantation, Tapian Kandis Village, Palembayan District, Agam Regency, West Sumatra, Indonesia

kasmaiswari2020@gamil.com, rizasalma@yahoo.com, doni.putra@wilmar.co.id

Keywords: Biogas; Electricity Efficiency; POME

Abstract

The palm oil industry is a large contributor to greenhouse gases in Indonesia. The application of biogas from the palm oil mill effluent (POME) treatment plant has become one of the solutions so it has been implemented at PT Agro Masang Perkasa (AMP). The catch of methane gasses is carried out by covering the waste pond with High-density Polyethylene (HDPE) material to create anaerobic conditions in the waste pool. The data collection for 3 months. The parameters observed and recorded are those related to the operating conditions of the installation such as pH , temperature ( ), inlet and outlet COD concentration ( ppm ), percentage of COD reduction (%), percentage of methane gas produced (%), amount of biogas produced , the amount of biogas supplied to the engine and flare , and the total power produced . The research results show that the methane gas obtained has been utilized as a renewable energy source such as biogas in factories with a total gas flow supplied to the engine of 135957 , 121655 , and respectively, and an average power produced of 159530, 153168, and 160161 kWh per month during observations in January, February, and March 2022. Although not all of the captured biogas is used for electrical energy, the benefits of implementing this technology mean that PT AMP has an average electricity efficiency in January, February, and March 2022 of , and . Based on calculations, it is found that the use of biogas capture at PT AMP can provide cost efficiency in a year of IDR. 5.21 billion and can return the installation capital within 3.5 years.

Introduction

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Palm oil plays a vital role as a critical edible oil. Its industry stands out prominently in the broader global agricultural sector [1]. In 2022, Indonesian palm oil production reached 48.2 million tons. This production is also supported by the availability of Indonesian oil palm plantations covering an area of 15,3 million hectares [2]. In the process of extracting palm oil at palm oil mills, only of the total biomass ends up as palm oil, while the remaining is typically discarded as waste. It's common for each ton of fresh fruit bunches (FFB) to produce approximately tons of palm oil effluent (POME) and 0.2-0.3 tons of empty fruit bunches (EFB). The crude palm oil (CPO) extraction process generates a substantial amount of palm oil mill effluent (POME), averaging 0.5 per ton of oil palm FFB [1]. POME comprises waste materials from three main extraction process sources: sterilization, condensation, and hydro-cycloning [1, 3, 4]. So far, POME has mostly been carried out in open waste ponds, releasing methane gas which is a greenhouse gas into the air.
The palm oil industry has become a large contributor to greenhouse gases (GHGs) in Indonesia [4, 5]. Apart from the need for substantial land area, the release of greenhouse gases (GHGs) from this treatment system represents a significant environmental issue [6]. The emission of greenhouse gases has served as the primary catalyst for climate change. The potential to reduce greenhouse gas
emissions and harness energy from organic waste materials is receiving growing recognition and interest [7]. POME is typically seen as a severely contaminating wastewater originating from palm oil mills. Nevertheless, there exists significant potential for its conversion into renewable energy on a large commercial scale, particularly when integrated with wastewater treatment procedures. Through anaerobic treatment, POME can be processed to degrade organic substances, leading to the production of biomethane and biohydrogen [8].
Indonesia continues to strive to convince the international market that the Indonesian palm oil industry has been managed in an environmentally friendly manner. One of the efforts made is by implementing technology biogas in palm oil industry wastewater ponds. Biogas, which contains mainly methane, carbon dioxide, and a lesser amount of hydrogen, is created by subjecting this noxious effluent to anaerobic treatment. The biogas production process involves microbial synthesis stages, including hydrolysis, acidogenesis, acetogenesis, and methanogenesis. The formation of biogas occurs during the anaerobic degradation of POME by native microbial communities [3]. This method can solve the problem of environmental damage due to the release of methane gas and further can produce energy for industry and society [9, 10].
The biogas capture process of converting POME into energy can be done by degrading the POME anaerobically in a closed pond so that the methane gas produced can be collected. The collected methane gas can be converted into useful biogas because biogas itself has the same content as natural gas which can be used as fuel. The calculation assumption is that a factory with a production capacity of 45 tons/hour can produce 1 MW of electricity. These results can supply the electricity needs of around one village ( 1000 houses) [4]. Efforts are underway to mandate biogas capture at all palm oil mills. This measure is designed to reduce the release of greenhouse gases and highlights the pivotal role that the anaerobic digestion of palm oil mill effluent (POME) will play as a primary source of biogas for generating energy [11].
PT. Agro Masang Perkasa (AMP) plantation is one of the crude palm oil (CPO) processing companies in West Sumatra province which has started implementing technology to capture methane gas (biogas) from its wastewater ponds and use it as an energy source. This article aims to provide information about the application of this technology, both the benefits and efficiency of several parameters obtained by companies after implementing this technology, which is in line with the government's goal towards low-carbon development in the industrial sector.

Materials and Methods

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Materials and tools. The application of biogas capture technology has been carried out by PT AMP Plantation located in Tapian Kandis village, Palembayan District, Agam Regency, West Sumatra. Biogas capture is carried out by covering the waste pond with dimensions length x width x height . This is done to create anaerobic conditions in the waste pond. To convert methane gas into electrical power, a biogas power plant (biogas engine) is used. For gas distribution, PE pipes or stainless steel pipes have been used, because POME and biogas are corrosive. Flares are used to burn methane gas that is not used for energy. To determine the amount of methane gas produced, the gas analyzer GIR5500 serial No. 1-10304, Hitech Instruments Luton England brand, was used. Other materials and equipment used are baffles, floaters, pumps and pipes.

Methods. The parameters observed and recorded are those related to the operating conditions of the installation such as pH , temperature ( ), inlet and outlet COD concentration ( ppm ), percentage of COD reduction (%), percentage of methane gas produced (%), amount of biogas produced ( ), the amount of biogas supplied to the engine and flare , and the total power produced . Data was obtained from the person responsible for the PT AMP installation. The data used for the article is recorded data from January, February, and March 2022.
The biogas production process at PT. AMP starts with POME (Palm Oil Mill Effluent) being sent to a cooling pond to reduce its temperature and remove residual oil. The wastewater is then transferred to a mixing tank, where it is combined with fresh waste to adjust the pH level and maintain a stable
temperature. From there, the wastewater flows into a digester pond, where bacteria break it down, producing biogas. The biogas is collected using an HDPE membrane cover, while the treated waste is pumped into a storage pond for further treatment before being utilized in land applications.

Results and Discussions

The original version of this paper is available on https://www.scientific.net/EC.10.19.pdf

Operational Conditions of PT AMP. PT AMP, which is located in Tapian Kandis village, Palembayan District, Agam Regency, West Sumatra, has a plantation with an area of 14735 Ha and a factory with an area of which is on the edge of its plantation area. Everyday the factory processes average of 1259.7-1366.9 tons of fresh fruit bunches (FFB), which produces an average of day of POME (Figure 1), so that an average of POME is produced from the total fresh fruit bunches (FFB) that come in every day. This is in accordance with research of Ahmed, 2015[1] that one ton of fresh fruit bunch (FFB) releases almost of POME. For comparison, the POME production at another factory (PT. DAS) averages between day. With an average total of fresh fruit bunches (FFB) processed ranging from 391.5-465 tons per day [12].

The factory has several wastewater ponds, one of the ponds with dimensions length x width x height , designed to implement biogas capture technology. As can be seen in Figure 1, average POME of day is flowed into the installation. POME that is not put into the biogas capture installation is processed in open ponds and flowed to oil palm plantations using land use techniques to be used by oil palm plants to add nutrients. This also needs to be a concern for PT AMP in the future to process it, so that the degradation of this waste water does not release greenhouse gases into the environment.

Fig. 1. Operational condition of PT AMP Plantation during observation.

Fig. 1. Operational condition of PT AMP Plantation during observation.

From Table 1 it can also be seen that the pH and temperature of the biogas installation at PT AMP have met the requirements for producing methane gas. pH is another key factor influencing the growth of microbes responsible for biogas production in the reactor. For optimal biogas production, the pH in the reactor should be maintained between 6.8 and 7.2, with a tolerable range of about 4 9.5. Temperatures between , are known to offer better process stability[13]. Thermal pretreatment and solid loading can significantly enhance the treatment process of POME [14].

Table 1. pH and temperature of the biogas installation at PT AMP

Parameter
January
February
March

pH
Temperature
(°C)
pH
Temperature
(°C)
pH
Temperature
(°C)

out digester
8.00
38.00
8.20
38.90
8.30
38.00

sludge
8.00
38.00
8.10
38.90
8.20
38.00

Biogas Performance. The high COD content, reaching 46777.5-63124.3 ppm in POME can be converted into biogas through a processing system without oxygen (anaerobic). From Figure 2 it can be seen that the COD reduction reaches , and can produce methane gas of 52.1-54.6 %.

Fig. 2. COD reduction, methane gas produced, and efficiency of electricity used at PT AMP during observation.

Fig. 2. COD reduction, methane gas produced, and efficiency of electricity used at PT AMP during observation.

Not all of the captured methane gas is used as a renewable energy source, because more than half of it is still burned in flares. It can be seen in Figure 3 that the gas supplied to the engine is lower than that supplied to the flare. This happens because only one of the two engines is supplied with gas. The engine generates month from the supplied gas. Even though not all of the biogas captured is used for electrical energy, the benefits of implementing this technology have provided an average electrical efficiency for PT AMP in January, February, and March 2022 of 15.20 %, 22.49 %, and 20.96 %.
Palm Oil Mill Effluent (POME) is a highly polluting wastewater characterized by elevated chemical oxygen demand (COD) and biochemical oxygen demand (BOD), which can severely impact the environment, particularly water resources. However, POME also holds potential as a valuable resource for producing renewable bioenergies such as biomethane and biohydrogen through anaerobic digestion. This dual approach-combining wastewater treatment with the generation of renewable energy-not only addresses environmental concerns but also offers significant added value to the palm oil industry [8]. However, further technological development is needed to improve the efficiency in utilizing the energy produced. With advancements in anaerobic digester technology, POME has the potential to become a highly efficient biogas resource, significantly contributing to the growth of the renewable energy (RE) sector in the future [15]. Furthermore, advancing technologies like the development of an integrated biogas production and phycoremediation system is essential. This approach incorporates key components such as cultivating microalgae on POME, extracting valuable compounds, and upgrading biogas. By aligning POME treatment with resource recovery and renewable energy production, this strategy demonstrates significant environmental and economic benefits [16].

Fig. 3. Working capacity of the biogas installation at PT AMP during observation

Fig. 3. Working capacity of the biogas installation at PT AMP during observation

Economic Value. The calculation of the cost of capturing methane gas is based on power data produced from January to March with an average demand for petro 4 of month or year which is replaced by biogas. If the price of Petro is IDR 7560 , then we get a cost efficiency of IDR. 5.21 billion per year. The project cost of creating biogas capture technology is estimated at Rp. 18 billion, so it can be calculated that the return on project costs can be carried out within 3.5 years. The use of biogas derived from POME has the potential to provide energy for nations that produce oil palm, all the while averting the environmental consequences associated with its improper disposal [3].

Conclusion

The original version of this paper is available on https://www.scientific.net/EC.10.19.pdf

The application of technology for extracting methane gas from POME as a biogas energy source at PT AMP has a positive impact, both for PT AMP itself and the environment. The captured methane gas has been used as biogas to provide electricity for PT AMP. Meanwhile, not only releasing methane gas directly into the air, but also can reduce greenhouse gas emissions which will cause global warming, and can reduce environmental pollution due to liquid waste from palm oil mills. Even though not all of the biogas captured is used for electrical energy, the benefits of implementing this technology have provided an average electrical efficiency for PT AMP Plantation in January, February, and March 2022 of , and . Based on calculations, it was found that the use of biogas at PT AMP can provide cost efficiency in a year of IDR. 5, 21 billion and can return the installation capital within 3.5 years. However, further technological development is needed to improve the efficiency in utilizing the energy produced.

References

The original version of this paper is available on https://www.scientific.net/EC.10.19.pdf

Ahmed Y Yaakob Z Akhtar P and Sopian K, 2015 Production of biogas and performance evaluation of existing treatment processes in palm oil mill effluent (POME) Renew. Sustain. Energy Rev. 42 p. 1260-1278.

Directorate General of Estates, Ministry of Agriculture R of I, 2021 Statistical of National Leading Estate Crops Commodity 2020-2022 .

Ohimain E I and Izah S C, 2017 A review of biogas production from palm oil mill effluents using different configurations of bioreactors Renew. Sustain. Energy Rev. 70 p. 242-253.

Rajani A Kusnadi Santosa A Saepudin A Gobikrishnan S and Andriani D, 2019 Review on biogas from palm oil mill effluent (POME): Challenges and opportunities in Indonesia IOP Conf. Ser. Earth Environ. Sci. 293, 1.

Antoni A Siregar Y I and Suwondo S, 2021 Strategi pemanfaatan Palm Oil Mill Effluent (POME) sebagai sumber energi berkelanjutan di pabrik kelapa sawit PT. Meridan Sejati Surya Plantation Kabupaten Siak J. Zo. 4, 2 p. 50-59.

Choong Y Y Chou K W and Ismail N, 2018 Strategies for improving biogas production of palm oil mill effluent (POME) anaerobic digestion : A critical review Renew. Sustain. Energy Rev. 82, P3 p 2993-3006.

Aziz N I H A and Hanafiah M M, 2020 Life cycle analysis of biogas production from anaerobic digestion of palm oil mill effluent Renew. Energy 145 p. 847-857.

Lam M K and Lee K T, 2011 Renewable and sustainable bioenergies production from palm oil mill effluent (POME): Win-win strategies toward better environmental protection Biotechnol. Adv. 29, 1 p. 124-141.

Parinduri L, 2016 Analisa pemanfaatan POME untuk sumber pembangkit listrik tenaga biogas di pabrik kelapa sawit J. Electr. Technol. 3, 3 p. 180-183.

Firdausi M, 2020 Potensi POME Untuk Pembangkit Listrik Tenaga Biogas di Kabupaten Tanjung Jabung Barat PRESISI 22, 1 p. 1-6.

Kang Z et al., 2021 Biogas production enhancement by co-digestion of empty fruit bunch with palm oil mill effluent (POME): Performance and kinetic evaluation Renew. Energy 179 p. 766-777.

Sagala D Frimawaty E and Sodri A, 2024 Potensi energi terbarukan dari pemanfaatan energi biogas POME (Palm Oil Mill Effluent) sebagai sumber energi terbarukan di Provinsi Jambi Jurnal Ilmu Lingkungan 22, 1, p. 205-214

Wulandari W and Senda S P, 2022 Analysis of biogas production from palm oil mill effluent at different feed flow rates in biogas plant Sei Pagar Riau IOP Conf. Ser.: Earth Environ. Sci. 963012006

Khadaroo S N B A Grassia P Gouwanda D He J and Eong P, 2021 Biomass and Bioenergy Enhancing the biogas production and the treated effluent quality via an alternative Palm Oil Mill Effluent ( POME ) treatment process : Integration of thermal pretreatment and dewatering Biomass and Bioenergy 151, 106167 p. 1-15.

Ji C M Eong P P Ti T B Seng C E and Ling C K, 2013 Biogas from palm oil mill effluent (POME): Opportunities and challenges from Malaysia's perspective Renewable and Sustainable Energy Reviews 26 p. 717-726

Djarot I N Pawignya H Handayani T Widyastuti N Nuha Arianti F D Pertiwi M D Rifai A Isharyadi F Wijayantia S P and Nur M M A 2024 Enhancing sustainability: microalgae cultivation for biogas enrichment and phycoremediation of palm oil mill effluent-a comprehensive review Environmental Pollutants and Bioavailability 36, 1, 2347314 p. 301319

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The original version of this eBook is available on https://www.scientific.net/book/engineering-chemistry-vol-10/978-3-0364-1889-6

Engineering Chemistry, ISSN: 2813-6535, Vol. 10, pp 25-34

doi: 10.4028/p-x9ofP3

© 2025 The Author(s). Published by Trans Tech Publications Ltd, Switzerland.

Submitted:
2024-03-02

Revised:
2024-11-12

Accepted:
2025-01-15

Online:
2025-08-26

Synthesis of Pour Point Depressant from Black Soldier Fly Maggot Oil

The original version of this paper is available on https://www.scientific.net/EC.10.25.pdf

Nila Tanyela Berghuis , Jihan Asma Halifah , Muhammad Yahya Lubis , Astra Agus Pramana

¹Chemistry, Pertamina University, JI.Teuku Nyak Arief, Simprug-South Jakarta-12220, Indonesia.

Center Of Excellent: Downstream Pertamina University, JI.Teuku Nyak Arief, Simprug-South Jakarta-12220, Indonesia.

Petroleum Engineering, Pertamina University, JI.Teuku Nyak Arief Simprug- South Jakarta-12220, Indonesia.

a*nila.tanyela@universitaspertamina.ac.id, asma.jihan@gmail.com, muhammadyahya322@gmail.com,

Keywords: Black Soldier Fly, Crude Oil, Esterification, Maggot Oil, Paraffin, Pour Point Depressant.

Abstract

This Final Project research focuses on the synthesis of pour point depressant (PPD) from Black Soldier Fly (BSF) Maggot Oil to reduce the pour point of crude oil samples. Crude oil itself is a non-renewable energy source that is still in high demand in Indonesia, especially as a vehicle fuel. Crude oil contains paraffin wax, which can crystallize and hinder the transportation and production processes of crude oil. Therefore, this study aims to produce PPD from BSF maggots as an additive for crude oil to ensure its smooth flow. Maggots were chosen due to their high fatty acid content, ranging from to , making them a potential source for PPD. The method used for PPD synthesis involves esterification using a reflux process. Pour point testing will be conducted using the ASTM D-5853 method. The synthesized PPD could lower the pour point of crude oil by up to from the original . Characterization using FTIR testing successfully revealed C-O vibrations (ester groups) at the wave number range of while eliminating vibrations (carboxylic acid groups). GC-MS characterization was also conducted to identify the formed ester compounds. The GC-MS results showed that PPD 1 had the highest ester content at .

Introduction

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Crude oil is a non-renewable energy source. The need for crude oil in Indonesia is still very high. One of the most widely used crude oil processed products is as a vehicle fuel to fulfill daily life activities. It is noted that the need for crude oil in Indonesia reaches 1.4 million barrels per day (bpd) [1]. Meanwhile, according to the Special Task Force for Upstream Oil and Gas Business Activities (SKK Migas) in 2022, production of crude oil will only reach 616.6 thousand barrels per day (bpd) [2]. This is certainly a concern for the government to be able to increase the amount of production to meet current crude oil needs. Seeing the need for crude oil, the crude oil that has been produced will be transported and stored in tankers to be transported to oil refineries for further processing. As is known, crude oil contains many hydrocarbon chain compounds, one of which is paraffin wax. Paraffin wax is a saturated hydrocarbon compound that occurs naturally in nature, comes from minerals, has long, linear, branched chains, and has an empirical formula, namely . Paraffin wax generally has 18 to 36 carbon atoms (C18-C36) [3]. Paraffin wax can inhibit and affect the flow of crude oil in pipes when transported. This is because paraffin wax is stable at room temperature which makes it solidify when it is at room or low temperature [4,5]. Thus, paraffin wax is considered an obstacle in the process of transporting crude oil.
To handle this, an additive is needed, namely using a Pour Point Depressant (PPD) which functions to inhibit the formation of larger solids from paraffin wax so that crude oil can still flow at room or low temperature [6]. Generally, PPD is made from polymer materials with a mixture of organic solvents [7]. PPD is considered efficient and can be used sustainably without reducing the amount of crude oil production because there is no need to shut in wells [3]. Apart from that, PPD is also needed to reduce the pour point in crude oil samples. The commercial PPD that is widely used today is

Ethylene Vinyl Acetate (EVA) [8]. However, EVA has the disadvantage that it is not very effective in reducing the pour point value. Even though EVA is considered safe to use, if it is not handled properly or the waste is disposed of carelessly, it can cause pollution to the environment (Nur et.al. 2021) .

To replace the use of EVA compounds as PPD, one compound that has the potential to be used as PPD is the FAME (Fatty Acid Methyl Ester) compound. This is because the structure of FAME has a framework similar to paraffin (hydrocarbon). To obtain FAME, you can use fatty acids that can be obtained from maggots which are then esterified with an acid catalyst and reacted with an alcohol source. Maggots have protein levels of around and fatty acids of . The fatty acid content in maggots includes oleic acid, palmitic acid, lauric acid, linoleic acid, linolenic acid, and other types of acids . The highest content was found in lauric acid, namely . Looking at the high fatty acid content in maggots, it would be a shame if maggots were only used as animal feed. Therefore, maggots can be used as raw material for making PPD which is more environmentally friendly.

Material and Methods

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Materials. The materials used are oil from Black Soldier Fly maggot (BSF), methanol, ethanol, 2propanol and Phenolphthalein indicator were obtained from Merck, were obtain from Aldrich; and crude oil samples from Petroleum Engineering. All reagent and chemical used were of analytical grade. Meanwhile, the instruments used for analysis were Fourier-Transform Infrared Spectroscopy from Thermo-Fisher Scientific Nicolet Type iS5-iD1 and Gas Chromatography-Mass Spectrometry by Thermo-Scientific Trace 1310-MS Thermo-Scientific ISQ 9000.

Methods

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Determination of Free Fatty Acid Levels (%FFA)

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3 grams of maggot oil was weighed and then put into an Erlenmeyer flask. In a separate place, 30 mL of ethanol was heated for minutes at using a hotplate. Then, the Erlenmeyer flask containing maggot oil was added with heated ethanol and then homogenized. After that, 3 drops of PP indicator were added to the mixture. 0.05 N NaOH was put into the burette as a titrant. The mixture was titrated using 0.05 N NaOH until the color changed to light pink. This is done in duplicate. The volume of NaOH was recorded and the was calculated. The formula for calculating is as follows.

[Equation 1] [18]

Synthesis of Pour Point Depressant (PPD)

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The first step in the synthesis process is esterification using the reflux method. 50 grams of maggot oil was weighed and put into a three-neck flask. Next, the maggot oil is heated while stirring using a magnetic stirrer for 30 minutes at a temperature of . In a different container, methanol is prepared (the ratio of maggot oil and alcohol used is ). Then, is added to methanol. Then, the mixture of methanol and was heated for 15 minutes at . After heating, the mixture was put into maggot oil, and the esterification process was carried out for 2 hours at a temperature of with a speed of 400 rpm . After 2 hours, the results of the esterification process were put into a separating funnel for washing using warm distilled water. Washing is done . The washing results are left overnight until the organic phase and water phase are separated. If 2 phases have been formed, the water phase can be discarded, and the organic phase is taken for the next process, namely evaporation using a rotary evaporator. After evaporation, the results are weighed. This result is what is called Pour Point Depressant (PPD). The resulting PPD is calculated by the %yield value using the following equation:

Do the same for other variations of alcohol.

Pour Point Testing

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Testing of the pour point value of crude oil samples in this study was carried out using the ASTM D5853 standard method. The first is to carry out pre-treatment by heating the crude oil sample until it melts at a temperature of . The liquid crude oil sample was put into a test tube which was then injected with PPD from maggot oil which had been esterified with injection doses of , and . The temperature was observed every interval by tilting it to for 5 seconds. If the crude oil sample is no longer flowing, it will be the observation temperature, while for reporting temperature the pour point is the observation temperature added with .

Fig. 1. (a) Pour Point Testing Equipment Circuit, (b) Pour Point Test Observation Position

Fig. 1. (a) Pour Point Testing Equipment Circuit, (b) Pour Point Test Observation Position

Determination of Viscosity and Density Values of Pour Point Depressant (PPD) and Crude Oil.

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Determination of viscosity for crude oil samples was carried out using a digital viscometer (Viscometer NDJ-8S). The first thing to do is heat the crude oil so that it is stable at a temperature of 50 oC . There are 4 rotors (rotor 1, rotor 2, rotor 3, and rotor 4). Viscosity measurements started by using the smallest rotor, namely rotor 4 , at four different speeds , and 60 rpm . This is done on all rotors using the same speed. The viscosity value that appears on the screen is recorded, and the value with a percent above is selected. Meanwhile, density determination is carried out using a pycnometer. and the density value can be determined based on the following equation:

Characterization of Pour Point Depressant (PPD)

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Data analysis is carried out quantitatively and scientifically in the laboratory to answer the research problem formulation and test hypotheses. Analysis of pour point depressant (PPD) synthesis data was carried out by characterization of Fourier-Transform Infrared Spectroscopy (FTIR) using plat KBr and Gas Chromatography-Mass Spectrometry (GC-MS).

Results And Discussions

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Synthesis of Pour Point Depressant

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One of the raw materials in the synthesis of Pour Point Depressant (PPD) is fatty acids. The source of fatty acids used in this research is maggot oil. To determine the fatty acid content in maggot oil, the Free Fatty Acid (%FFA) level was tested. FFA testing is needed to control the quality and performance of PPD. According to Om & Achugasim (2023), the higher the %FFA level, the lower the stability of the oil, so its effectiveness as a PPD to reduce the pour point of crude oil will also be lower [16]. In this study, FFA testing was carried out using the acid-base titration method. The average %FFA content of maggot oil is . Usually, the ideal %FFA level for PPD is around 0.1 . However, FFA levels can still be tolerated and varied through esterification reactions. Therefore, an esterification process was carried out on maggot oil. The esterification process for maggot oil uses the reflux method with a ratio of maggot oil and alcohol of 1:6. The alcohols used include methanol, ethanol, and 2-propanol. Before the esterification process is carried out, the alcohol
and catalyst, namely , are mixed and heated for 15 minutes at . In this process, alcohol is not a solvent, but a reactant with the catalyst. The results of synthesis using the reflux method produce three products, namely PPD 1 ( ), PPD 2 ( ), and PPD 3 ( ).
After the %yield value was found, the PPD product was then tested for %FFA levels again to check whether the esterification process was successful in reducing the %FFA content of maggot oil which was previously . for PPD 1 and PPD 2, the %FFA level decreased, namely to and . The decrease in the %FFA levels of PPD 1 and PPD 2 indicates that it is true that the esterification process can reduce the %FFA levels. On the other hand, for PPD 3 the calculation results for the %FFA level increased to . The %FFA value of PPD 3 is the highest, which means that in PPD 3 the amount of free fatty acids is the highest. Another cause is that the results of PPD 3 are mostly re-hydrolyzed in the esterification process when the synthesis is carried out.

Table 1. Summary of % Yield and FFA Levels

No | Sample | Name of Alcohol | %Yield | %Average FFA
1 | PPD 1 | Methanol | 75,565% | 0,63
2 | PPD 2 | Ethanol | 89,592% | 1,08
3 | PPD 3 | 2-Propanol | 94,527% | 1,45

%Average FFA

The FFA values is lower than the reference by Afifah, 2020.

FTIR Characterization of Pour Point Depressant (PPD) and BSF Maggot Oil

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The process was identifying functional groups and wave numbers for PPD and maggot oil samples was characterized using Fourier-Transform Infrared Spectroscopy Attenuated Total Reflection (FTIR-ATR). Below in Figure 2 below is the spectrum of the synthesized maggot oil and PPD samples.

Fig.2. FTIR spectrum of Maggot Oil, PPD 1, PPD 2, and PPD 3

Fig.2. FTIR spectrum of Maggot Oil, PPD 1, PPD 2, and PPD 3

Table 2. FTIR spectrum analysis of Maggot oil, PPD 1, PPD 2, and PPD 3

Vibration | Functional Groups | Wavenumber (cm⁻¹) | Literature
|  | Maggot Oil | PPD 1 | PPD 2 | PPD 3 | Kathumbi, et al. (2022), [17] | Kamari, et al. (2020) [18]
O-H- bending | Carboxylate Acid / Alcohol | 3470 | - | - | - | 3480 cm⁻¹ | -
C-H aliphatic (Stretching) | Aliphatic (–(CH₂)n) | 2850 | 2921 | 2921 | 2921 | 2926 cm⁻¹ | 2920 dan 2851 cm⁻¹
C=O (Stretching) | Ester | 1750 | 1742 | 1742 | 1740 | 1741 cm⁻¹ | 1741 cm⁻¹
C-O (Stretching) | Ester | - | 1155 | 1155 | 1158 | 1458 cm⁻¹ | 1160-1110cm⁻¹

When compared with reference data, there is a shift where the vibration is at a wave number of . The vibrations in maggot oil are small. The shift is also indicated by asymmetric C H stretching vibrations at a wave number of . The peak at wave number is also not sharp, so the presence of and stretching vibrations indicates that little fatty acids contained in maggot oil are used. This is also supported by the previously determined %FFA of maggot oil, namely . The stretching vibrations in maggot oil are at a wave number of .
The wave number shift occurs because the components in maggot oil and PPD products are different. Where maggot oil contains triglycerides and free fatty acids. Initially, in maggot oil, the C-H vibrations were in the triglyceride framework, namely in the alkyl part. Then, there was a change in PPD products containing ester compounds. If concluded, the vibration comes from triglycerides and free fatty acids contained in maggot oil, while in PPD products the C-H vibration comes from the alkyl part of the ester. This causes a shift in the wave number. Then, for vibrations, the wave number shift is not too far because the vibrational character of maggot oil and PPD is not different, both originate from the ester group, so the wave number shift does not change significantly. The most significant difference between maggot oil and PPD samples is the O-H and C-O vibrations. The maggot oil sample has vibrations, whereas in the PPD sample, these vibrations are lost. Likewise, in maggot oil, there are no C-O vibrations, while C-O stretching vibrations appear in the three PPD products, namely at wave numbers 1155 and . As it is known that the-C-O-C bond is part of the ester, the disappearance of vibrations and the appearance of vibrations in the three PPD products that have been synthesized indicates that the esterification reaction of maggot oil has been carried out successfully. All the vibrations have been comparing with the reference by Kathumbi, et al 2022 and Kamari, et al 2020.

GC-MS Characterization of Pour Point Depressant (PPD)

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The synthetic PPD product was subjected to GC-MS characterization to determine the content of ester compounds in it. The following is Figure 3 which shows the chromatogram of PPD 1-PPD 3.

Fig. 3. GC-MS chromatogram of PPD 1-3

Fig. 3. GC-MS chromatogram of PPD 1-3

For PPD 1, based on the chromatogram data above, 78 peaks appear with retention times between 2.24-20.57 minutes. To find out which ester compounds from the PPD synthesis result are dominant, %Area calculations are carried out. If seen from the %Area, Hexadecenoic acid, methyl ester is the most dominant compound, namely at a retention time of 16.56 minutes. If you look at the %Area comparison above, there are still fatty acid compounds in the PPD 1 product, namely 5.88%. Then, the total % area of the alkyl ester compound, namely methyl ester, was obtained at .
For PPD 2, based on the chromatogram data above, 67 peaks appear with retention times between 2.24-23.03 minutes. Based on GC-MS analysis, it shows that of Undecanoic acid, ethyl ester was formed at a retention time of 12.99 minutes, while the remaining fatty acid, namely Thioacetal acid, was identified at a retention time of 2.24 minutes with a %Area of .
For PPD 3, based on the chromatogram data above, 38 peaks appear with retention times between 9.66-26.95 minutes. The dominant propyl ester compound in PPD 3 is Hexadecenoic acid, propyl ester, or propyl palmitate at a retention time of 17.73 minutes with the highest %Area, namely . Apart from that, PPD 3 still contains fatty acids with a total %Area of 4.75%. Meanwhile, the total propyl ester formed was .
A comparison between the % area of alkyl esters and fatty acids contained in each PPD product that has been synthesized is summarized in Table 3.

Table 3. % Area of Alkyl Ester and Fatty Acids PPD 1, PPD 2, PPD 3

Type Of PPD | % Area
| Alkyl Esters | Fatty Acids
PPD 1 | 87,71 | 5,88
PPD 2 | 1,42 | 0,48
PPD 3 | 42,90 | 4,75

From the results in Table 3, the highest % area of alkyl esters is PPD PPD PPD 2. The % area value for PPD 1 reaches which indicates that many esters produced from the esterification process are formed even though they are not perfect as proven by There are still fatty acid compounds contained in it, although it is relatively small, namely only 5.88%. Meanwhile, the %Area PPD 2 obtained was the smallest, indicating that ester formation was not optimal.
The reaction used is esterification, the basic principle of esterification itself is a substitution reaction. The main factor in substitution reactions is the aspect of nucleophilicity. Nucleophilicity in this reaction is represented by the presence of alcohol. If you look at the functional groups involved, they are all alcohols, so the electron source aspects are the same. However, what differentiates %Area is from the alkyl attached to the alcohol. The presence of alkyl can interfere with the nucleophilicity of OH . Disturbances can be seen from the presence of steric hindrance. The one with the strongest steric hindrance is ethanol, so that when ethanol wants to enter the C atom in the carboxylic acid it will be
blocked and cause the ester yield for PPD 2 to be small. Furthermore, 2-propanol has many carbons but is branched, so it is still better than ethanol. And if you look at the reaction mechanism, the nucleophilic character of methanol is strong. Compared to the other two alcohols, methanol has a lower steric hindrance and tends to be lighter because it only has one C atom, so it is easier to attack the C atom in the positively charged carboxylic acid. The ease with which methanol attacks causes PPD 1 to produce more esters which are indicated by the size of the %Area.

Pour Point Testing

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Pour point testing was carried out to determine the effect of adding additives, namely synthesized PPD. The method used in testing is ASTM D-5853 [19,20] with a minimum pour point type which focuses more on the delay in the formation of paraffin wax. The results of the crude oil pour point test can be seen in Table 4 below.

Table 4. Crude Oil Pour Point Test Results

%PPD | Injection Dosage (mL) | Pour Point (°C)
| PPD | Crude Oil | Blank | Maggot Oil | PPD 1 | PPD 2 | PPD 3
0 | 0 | 5 | 39 | - | - | - | -
8 | 0,4 | 4,6 | - | 39 | 39 | 33 | 33
10 | 0,5 | 4,5 | - | 36 | 39 | 33 | 33
12 | 0,6 | 4,4 | - | 39 | 21 | 36 | 33
14 | 0,7 | 4,3 | - | 39 | 21 | 33 | 33
16 | 0,8 | 4,2 | - | 39 | 15 | 33 | 30

In crude oil injected with PPD 1, the decrease was quite drastic, namely decreasing by to at an injection dose of . PPD 2 can only reduce the pour point of crude oil by , even when the dose is increased to the pour point value remains and no further decrease occurs. As stated by Afdahl (2022), the dosage of PPD for each type has an optimum point for the pour point value. So, even if the dose is increased, if it has reached the optimum point, the pour point temperature will not decrease [15]. The final test was to use PPD 3 which only slightly lowered the crude oil pour point by . So, the PPD that is effective for lowering the pour point of crude oil is PPD 1 which uses methanol alcohol. This can occur due to the strong van der Waals interaction between PPD and paraffin wax when PPD is added to crude oil, resulting in inhibition of the formation of paraffin wax so that crude oil can still flow at low temperatures. Maggot oil which contains the fatty acid lauric acid reacts with methyl ester to produce a longer chain (Figure 4), so it can interact with paraffin wax. This is because PPD has two sides, polar and nonpolar. The polar side containing oxygen atoms will produce steric interference when PPD is added to crude oil. After the interaction between crude oil and paraffin wax is broken, the paraffin wax will interact with the nonpolar side of PPD [20].

Fig.4. Mechanism of Paraffin Wax Inhibition by PPD 1 [20]

Fig.4. Mechanism of Paraffin Wax Inhibition by PPD 1 [20]

Viscosity and Density Test Results

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Pour point reduction is also influenced by viscosity and density. The following are the results of the viscosity and density tests which can be seen in Table 5 below.

Table 5. Results of Determining Viscosity and Density Values

Sample | Viscosity (cSt) | Density (kg/m³)
Crude Oil | 27,8 | 751,1
PPD 1 | 18,32 | 833,6
PPD 2 | 20,37 | 834,3
PPD 3 | 18,15 | 831,6

From the results obtained, the viscosity and density values of PPD 1 are quite low, although not as low as those of PPD 3. Viscosity means viscosity, where the lower the viscosity value, the more soluble it will be, and helps to lower the pour point value. This also applies to density where the lower the PPD density value, the more effective it will be in reducing the pour point value of crude oil. Then, if we look at the ester recovery produced based on GC-MS characterization, PPD 1 will be more effective than PPD 3. This is because PPD 1 has a higher amount of ester, namely , whereas for PPD 3 the ester recovery only reaches . So, it can be concluded that the most effective PPD for reducing the pour point value of crude oil is PPD 1 .

Conclusions

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The PPD synthesis was successfully carried out with the highest %yield values is for PPD 3 . The addition of synthetic PPD can reduce the pour point value of crude oil, PPD 1 reduced with , PPD 2 reduced it by with , and PPD 3 reduced it by with . The viscosity value of PPD is in the range St. Then, the PPD density value is in the range of . The FTIR characterization obtained is that the synthetic PPD contains an ester functional group ( ) at a wave number of and there is no carboxylic acid (O-H) group which was originally at a wave number of . And GC-MS analysis succeeded in validating the ester compounds formed and the fatty acids. The characterization results show that the amount of ester for PPD 1 is , for PPD 2 it is , and for PPD 3 the amount of ester is .

Acknowledgment

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Thank you to Pertamina University for the Internal Grant Funds which have funded this research activity.

References

The original version of this paper is available on https://www.scientific.net/EC.10.25.pdf

M. Idris, "Berapa Produksi Minyak Indonesia saat ini?," 2022. [Online]. Available: https://money.kompas.com/read/2022/07/16/000300326/berapa-produksi-minyak-indonesia-saat-ini-.

Pasasa, N. V. A., Kasmungin, S., & Pramana, A. A. (2017, October). Studi Pemilihan Pour Point Depressant Untuk Penanggulangan Masalah Transportasi Minyak Parafinik Pada Lapangan X. In Prosiding Seminar Nasional Cendekiawan (pp. 211-217).

Ayundari, D. P. N., & Sutjahjo, D. H. (2018). Rancang Bangun Alat Uji Pour Point Untuk Mengukur Titik Tuang Bahan Bakar. Jurnal Rekayasa Mesin, 5(1).

Afriana, D., & Dhamayanthie, I. (2018). Analisa Fraksi Gasoil Berdasarkan Uji Sifat Fisika. IPTEK Journal of Proceedings Series, (2).

Kurnianto, M., & Prasetyo, A. (2018). Prediksi Kedalaman Terbentuknya Wax Pada Sumur X Lapangan Y. PETRO: Jurnal Ilmiah Teknik Perminyakan, 7(2), 65-72. .

Prabowo, A. S. (2021). Peranan Penting Injeksi Pour Point Depressant (PPD) Untuk Menjaga Aliran Crude Oil Saat Terjadinya Penurunan Temperatur Pada Export Line Lapangan AS (Doctoral dissertation, Universitas Islam Riau).

Yang, F., Zhao, Y., Sjöblom, J., Li, C., & Paso, K. G. (2015). Polymeric wax inhibitors and point depressants for waxy crude oils: a critical review. Journal of Dispersion Science and Technology, 36(2), 213-225. .

Nurfajrin, Z. D., Satiyawira, B., & Putra, R. A. (2021, November). Comparison of pour point depressant (PPD) ethylene-vinyl acetate (EVA) and nano-montmorillonite. In IOP Conference Series: Earth and Environmental Science (Vol. 894, No. 1, p. 012019). IOP Publishing. .

Nur, A. A., & Subekti, H. (2021, December). Mgs-25 Ethylene-Vinyl Acetate (Eva) Copolymer Sebagai Pour Point Depressant Pada Waxy Crude Oil. In Prosiding Seminar Nasional Teknologi Energi dan Mineral (Vol. 1, No. 2, pp. 101-107).

Putra, R. A. (2022). Studi laboratorium perbandingan Pour Point Depressant (PPD) Ethylene Vinyl Acetate (EVA) dan Nano-montmotillonite. SKRIPSI-2021.

Izzatusholekha, I., Jabbar, M. F. A., Rahmawati, R., Salmah, S., & Prasdianto, R. (2022, October). Lalat Tentara Hitam (Black Soldier Fly) Sebagai Pengurai Sampah Organik (Black Soldier Fly As An Organic Waste Decomposer). In Prosiding Seminar Nasional Pengabdian Masyarakat LPPM UMJ (Vol. 1, No. 1).

Santi, S., Astuti, A. T. B., & Pasamboang, J. (2020). Nilai Nutrisi Maggot Black Solder Fly (Hermetia Illucens) dengan Berbagai Media. AGROVITAL: Jurnal Ilmu Pertanian, 5(2), 9193. .

Putra, A. T. M., Salim, A., Fauziah, R. N., & Alzana, N. (2022, June). Pemanfaatan Senyawa Antimicrobial Maggot (Hematia Illuecens) Sebagai Agen Bakteriolitik Gram Negatif. In Prosiding Seminar Nasional Teknologi Agribisnis Peternakan (Stap) (Vol. 9, pp. 813-819).

Ewald, N., Vidakovic, A., Langeland, M., Kiessling, A., Sampels, S., & Lalander, C. (2020). Fatty acid composition of black soldier fly larvae (Hermetia illucens)-Possibilities and limitations for modification through diet. Waste management, 102, 40-47. .

Afdhol, M. K., Rita, N., Hidayat, F., & Erfando, T. (2022). Pembuatan Green-Solvent Dari Limbah Kulit Nanas dan Pemanfaatannya Sebagai Wax Inhibitor. Lembaran publikasi minyak dan gas bumi, 56(3), 125-130. .

Shittu, O. M., & Achugasim, O. (2023). Modified and Unmodified Jatropha Curcas Seed Oils as Pour Point Depressants for a Nigerian Waxy Crude Oil. Journal of Applied Sciences and Environmental Management, 27(2), 237-242. .

Kathumbi, L. K., Home, P. G., Raude, J. M., & Gathitu, B. B. (2022). Performance of Citric Acid as a Catalyst and Support Catalyst When Synthesized with NaOH and CaO in Transesterification of Biodiesel from Black Soldier Fly Larvae Fed on Kitchen Waste. Fuels, 3(2), 295-315.- .

Kamari, A., Ishak, S., Hussin, M. I. A. M., Wong, S. T. S., Jumadi, J., & Yahaya, N. M. (2020, December). Optimization and characterization studies of biodiesel production from black soldier fly larvae fed by soya residue. In IOP Conference Series: Materials Science and Engineering (Vol. 980, No. 1, p. 012057). IOP Publishing. .

Patra, S., & Migas, M. I. P. Perbandingan Hasil Pengujian Pour Point pada Crude Oil Menggunakan Metode Uji ASTM D 97 dan ASTM D 5853.

Afifa, S. (2022). Sintesis Polietilena Glikol Ester dari Ampas Kopi serta Aplikasinya Sebagai Pour Point Depressant (Bachelor dissertation, Sayyidah Afifa).

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Engineering Chemistry, ISSN: 2813-6535, Vol. 10, pp 35-42

doi: 10.4028/p-vhbs2E

© 2025 The Author(s). Published by Trans Tech Publications Ltd, Switzerland.

Submitted:
2025-01-23

Revised:
2025-04-15

Accepted:
2025-04-23

Online:
2025-08-26

The Potential of Fly Ash Based Geopolymer Coatings for Steel Corrosion Protection

The original version of this paper is available on https://www.scientific.net/EC.10.35.pdf

Sarini Mat Yaakob , Suriati Sufian and Nurul Ekmi Rabat

Mechanical Engineering Department, Universiti Teknologi PETRONAS, 32610, Seri Iskandar, Perak

Chemical Engineering Department, Universiti Teknologi PETRONAS, 32610, Seri Iskandar, Perak

riniyaakob@gmail.com, suriati@utp.edu.my, nurulekmi.rabat@utp.edu.my

Keywords: coating, corrosion, geopolymer, fly-ash based, immersion

Abstract

Nowadays, researchers are trying to understand whether geopolymers have the potential to be used as a coating material, particularly for protecting metal from corrosion attack. This study aimed to evaluate the effectiveness of fly ash-based geopolymer coatings in protecting steel by immersing the coated samples in a solution for immersion periods of , and 28 days. The uncoated steel showed the NaCl color changed to yellowish and became darker with increasing immersion time, indicating severe corrosion on the uncoated steel after 28 days. Surprisingly, with 3 mm geopolymer thickness coated on the steel, NaCl solution remain unchanged until 28 days immersion period. The corrosion rate exhibits a very gradual increase, with only year recorded after 28 days of immersion. No defects such as blistering, peeling, or cracking were observed on the coated steel. These results indicate that geopolymer holds considerable promise as a coating material, warranting further investigation for its potential applications in this area.

1. Introduction

The original version of this paper is available on https://www.scientific.net/EC.10.35.pdf

In civil engineering, protection of the structure becomes primary concern. The application of protective coatings is beneficial due to their resistance to acids, alkalis, and salts. It also can protect the structure from the severe civils environments such as humidity and moisture, high and low temperature and freeze-thaw cycles. Most frequently coating which has been used to protect the structure is an organic coating such as acrylic, polyurethane, epoxy, alkyd coatings [1]. While organic coatings offer significant advantages in protecting civil engineering structures, they also come with certain disadvantages such as become rigid and crack under thermal or mechanical stress if not formulated for flexibility [2], toxicity concerns due to release of volatile organic compound [3] and shorter lifespan [4]. Cement based coating materials are the most common inorganic coating materials used in structure protection. Although these coatings can give high durability, yet, less focus have been paid on their protection mechanism and performance. The focus has been given in understanding the function of cement-based coatings as a surface treatment which discussing on the overlay, pore blocking and hydrophobic impregnation. Overlay coatings will serves as a barrier to inhibit substance exchange between steel surface with environment [5]. Hydrophobic impregnation coatings functioning by adjusting surface state so that it will becomes hydrophobic [6]. Pore blocking machine was applied normally to the highway bridges to barricade capillary pore in the substrate, thereby enhancing its permeability [7].

Recently, a new category of inorganic coatings, primarily composed of geopolymers, has been explored and utilized for protecting concrete and steel surfaces [8]. Geopolymers are a kind of inorganic polymers typically synthesized via alkaline activation of aluminosilicate precursor. Geopolymers are inorganic polymers formed through the alkaline activation of aluminosilicate
precursors. Their unique spatial network structures, resulting from the geopolymerization process, make them well-suited for coating and surface protection applications. These materials are often characterized by their exceptional mechanical strength, chemical stability, water resistance, and thermal durability [9]. Study by Zhang et al. [10] on the sodium aluminosilicate hydrate (NASH) gel in marine environment found the chemically binding water to the Si -Al skeleton weaking tensile strength of the coating. Meanwhile, the feasibility of geopolymer as a fire-retardant coating material was studied by Temuujin et al. [11], who found that geopolymer successfully protected the panel and able to withstood fire heat up to a . observing the vast potential of geopolymer for application as a coating material, had conceived the idea for the present work to be carried out. This research aims to evaluate the performance of fly ash-based geopolymer in protecting steel from corrosion and to determine the minimum corrosion rate achievable with geopolymer coating.

2. Material and Methods

The original version of this paper is available on https://www.scientific.net/EC.10.35.pdf

Coal fly ash was sourced from a local power plant in Malaysia. To ensure consistency in particle size distribution and eliminate larger particles, the fly ash was sieved through a mesh using a vibratory sieve shaker (AS200 Basic, RETSCH, Germany). The geopolymer was synthesized using a sodium hydroxide ( , Merck, Darmstadt, Germany) alkaline solution, with sodium-toalumina and water-to-solid ratios set at 1.0 and 0.33 , respectively. For the corrosion test, a carbon steel plate with dimensions of was prepared. Before the coating process, the plate underwent surface finishing using abrasive paper of a specific grade. Grinding was done using waterproof silicon carbide paper (CarbiMet, Buehler, USA) of various grit sizes (P240 to P1200).

To remove impurities, the plate was degreased with distilled water and acetone (analytical grade, Merck, Darmstadt, Germany). The pretreated steel plate was coated with geopolymer paste using dip coating method, whereby the plate was dipped in the paste for 10 seconds. It was then taken out and suspended for 30 seconds to remove excess geopolymer. The coating process is illustrated in the schematic image Figure 1. A digital Vernier caliper (model 530-122, Mitutoyo Corp., Kanagawa, Japan) was used for cured sample's thickness measurement. Only samples with a thickness of 3 mm were accepted for further corrosion testing.

Fig.1 Dip method to coat the steel plate with geopolymer coating

Fig.1. Dip method to coat the steel plate with geopolymer coating

The pretreated steel substrate was then coated with 3 mm thickness geopolymer paste using a dip-coating method for 10 seconds. Subsequently, it was isothermally cured in an oven at for three days. The coated steel was immersed in solution for and 28 days. The solution's color change was monitored, and the corrosion rate was measured using the weight loss method. Equation 1 shows the formula used to calculate the corrosion rate using weight loss method [12].

(Equation 1)
where, is weight loss of the material ( g ), A is surface area of the material exposed to the corrosive environment ( ), T is time of exposure (hours), D is density of the material ( ) and K is conversion factor (typically for corrosion rate in year when using , hours, and )

3. Results and Discussion

The original version of this paper is available on https://www.scientific.net/EC.10.35.pdf

Table 1 presents the corrosion rates recorded after immersion periods of , and 28 days. The bare sample, serving as the benchmark, was used as a reference to assess the performance of the coated sample. As shown in the table, the bare sample experienced severe corrosion over time, with the corrosion rate increasing from year after 1 day to year after 28 days. Notably, coating the steel surface with geopolymer significantly reduced the corrosion rate, achieving a minimum of year after 28 days of immersion. Geopolymer coating can protect steel from environmental degradation primarily through its dense, chemically stable, and impermeable structure. The coating acts as a physical barrier, preventing the penetration of corrosive agents such as chloride ions, oxygen, and moisture, which are key contributors to steel corrosion [13]. Additionally, geopolymers exhibit excellent chemical resistance and possess a high pH environment that can help maintain the passivation layer on the steel surface, further reducing the risk of corrosion [14]. These properties make geopolymer coatings a promising alternative for enhancing the durability of steel structures, especially in harsh environments.

According to the current literature, there are no available studies on unfilled geopolymer coatings for corrosion rate inhibition that can be used for direct comparison with the present study. Most existing research focuses on the performance of geopolymer coatings incorporating fillers and additives. Some findings on filler/additive-based coatings were referenced to observe differences in corrosion rates. It is undeniable that the addition of fillers and additives significantly enhances the performance of geopolymer coatings. Yang et al. [15] incorporated graphene oxide as a filler in geopolymer coatings, and the Ecorr results demonstrated that the modified graphene oxide coating provided the highest level of corrosion inhibition. Similarly, Tomar et al. [16] utilized gamma alumina/zinc phosphate as an additive in a fly ash-red mud geopolymer coating to enhance its protective capabilities. Their study achieved a minimum corrosion rate of year with an inhibition efficiency of 96.69%.

Table 1. Corrosion rate of uncoated and coated steel for , and 28 days of immersion time

Bare (uncoated) steel | Coated steel
Immersion time | Weight loss(mg) | Corrosion rate(mm/yr) | Immersion day | Weight loss | Corrosion rate(mm/yr)
1 | 33.21 | 0.23 | 1 | 12.79 | 0.089
7 | 251.62 | 0.25 | 7 | 97.63 | 0.097
14 | 543.49 | 0.27 | 14 | 207.33 | 0.103
28 | 1127.26 | 0.28 | 28 | 450.90 | 0.112

Figure 2 shows the solution becomes increasingly darker and yellowish over the immersion period, indicating the accumulation of rust precipitates on the steel surface due to corrosion. The darkest coloration is observed after 28 days of immersion. Without a protective coating, the steel surface is exposed to aggressive chloride ions, which readily attack the surface. Through the redox process, rust formation becomes evident on the steel [17]. As the redox reaction progresses over time, prolonged immersion allows more corrosive species to penetrate the underlying steel surface, exacerbating the severity of corrosion [18].

Fig. 2. Uncoated steel in solution for , and 28 days of immersion time with control solution

Fig. 2. Uncoated steel in solution for , and 28 days of immersion time with control solution

The effectiveness of the geopolymer in protecting the steel surface from corrosion is evident in Figure 3. From day 1 to 28 days of immersion, the solution remains clear without any yellowish tint, indicating minimal and controllable rust formation on the steel surface. This is attributed to the geopolymer coating forming a dense and impermeable layer over the steel, preventing the penetration of corrosive agents such as oxygen, water, and chloride ions, which drive the corrosion process. Additionally, geopolymers are inherently chemically stable and resistant to harsh environments, maintaining their integrity as a protective barrier [1]. As shown in Table 1, the lowest corrosion rate at 28 days for the coated steel demonstrates that the geopolymer coating adheres strongly to the steel surface, providing a consistent and long-lasting protective layer. However, further investigation is needed to improve geopolymer fabrication, as the microstructure of the coatings is expected to have very low porosity. Despite this, corrosion still occurs over time, albeit at a significantly reduced rate.

Fig. 3. Fly ash based geopolymer coated steel in solution for , and 28 days of immersion time

Fig. 3. Fly ash based geopolymer coated steel in solution for , and 28 days of immersion time

After 28 days of immersion, the geopolymer coatings were evaluated for potential defects on the coated steel. As shown in Table 2, no defects such as bubbles, blisters or cracks were observed on the coated sample.

Table 2. Potential defects on coated steel

Steel | Bubbling | Blistering | Cracking
coated (1 day) | No | No | No
coated (7 days) | No | No | No
coated (14 days) | No | No | No
coated (28 days) | No | No | No

Further evaluation using SEM (as shown in Figure 4) was performed on the coated sample to assess the presence of cracks within the coating. The results indicated that no cracks were observed from the first day until 28 days of immersion time. This can be attributed to the tightly packed geopolymer structure, which effectively minimized void formation that could potentially act as crack initiators. Additionally, the image confirms that a 3 mm coating thickness is sufficient to provide effective protection for the steel, preventing corrosion by eliminating liquid entrapment beneath the layer during and after application.

Fig.4. Morphology image of steel coated for 1, 7, 14 and 28 days

Fig.4. Morphology image of steel coated for 1, 7, 14 and 28 days

Overall, the results demonstrate the potential of fly ash based geopolymer coating for steel corrosion protection. The SEM analysis further confirmed the formation of a dense and homogeneous geopolymer matrix, supporting the corrosion test results. These findings provide a strong basis for the conclusions drawn in the following section.

4. Conclusions

The original version of this paper is available on https://www.scientific.net/EC.10.35.pdf

Geopolymer coatings are gaining increasing attention in both academic research and industrial applications due to their unique properties and sustainability advantages. Several factors contribute to their growing interest such as environmental and sustainability benefits, superior corrosion and fire resistance. They have low carbon emissions compared to traditional organic coatings or cement-based coatings. Unlike organic coatings, geopolymer coatings are highly resistant to heat, acids, and harsh environments, making them suitable for extreme conditions such as marine structures, industrial plants, and fireproofing applications.
In this study, a fly ash-based geopolymer was successfully developed and applied as a coating on a steel surface to assess its effectiveness in corrosion inhibition. The results indicate that the geopolymer coating effectively controls corrosion, as shown by the minimal increase in corrosion rate observed from day 1 to day 28 . The absence of yellowish discoloration in the test solution confirms the coating's effectiveness in preventing rust formation. Based on the findings of this research, one potential application of the geopolymer coating is its use as an internal protective layer within reinforced concrete structures. Instead of embedding bare steel reinforcement directly into concrete, the application of a geopolymer coating on the steel surface before placement can serve as an additional barrier against corrosion. This approach addresses a critical issue in structural durability, as corrosion of embedded steel can lead to significant deterioration, reducing the lifespan and integrity of concrete structures. By preventing or slowing down the initiation of corrosion, the geopolymer coating can enhance the long-term performance of reinforced concrete, particularly in aggressive environments such as coastal or marine structures.

Declaration of competing interest

The original version of this paper is available on https://www.scientific.net/EC.10.35.pdf

The authors do not have any conflict with other entities or researchers.

Acknowledgement

The original version of this paper is available on https://www.scientific.net/EC.10.35.pdf

This study was supported by Universiti Teknologi PETRONAS, Malaysia under Graduate Research Assistant (GRA) grant.

Author contributions

The original version of this paper is available on https://www.scientific.net/EC.10.35.pdf

All authors contributed equally to this work

Data availability

The original version of this paper is available on https://www.scientific.net/EC.10.35.pdf

Data will be made available on request

References

The original version of this paper is available on https://www.scientific.net/EC.10.35.pdf

C. Jiang, A. Wang, X. Bao, T. Ni, and J. Ling, A review on geopolymer in potential coating application: Materials, preparation and basic properties, Journal of Building Engineering. 32 (2020) 101734

S. Chen, Y. Li, D. Yan, C. Wu, and N. Leventis, Piezoresistive geopolymer enabled by cracksurface coating, Materials Letters. 255 (2019) 126582

C. Liu, R. Zong, H. Chen, J. Wang, and C. Wu, Comparative study of toxicity for thermoplastic polyurethane and its flame-retardant composites, Journal of Thermoplastic Composite Materials. 32 (2019) 1393-1407

H. Wang, P. Feng, Y. Lv, Z. Geng, Q. Liu, and X. Liu, A comparative study on UV degradation of organic coatings for concrete: Structure, adhesion, and protection performance, Progress in Organic Coatings. 149 (2020) 105892

H. Y. Moon, D. G. Shin, and D. S. Choi, Evaluation of the durability of mortar and concrete applied with inorganic coating material and surface treatment system, Construction and Building Materials. 21 (2007) 362-369

M. V. Diamanti, A. Brenna, F. Bolzoni, M. Berra, T. Pastore, and M. Ormellese, Effect of polymer modified cementitious coatings on water and chloride permeability in concrete, Construction and Building Materials. 49 (2013) 720-728

J.-G. Dai, Y. Akira, F. H. Wittmann, H. Yokota, and P. Zhang, Water repellent surface impregnation for extension of service life of reinforced concrete structures in marine environments: The role of cracks, Cement and Concrete Composites. 32 (2010) 101-109

F. Farhana, M. Fazill, H. Kamarudin, A. Rahmat, M. M. A. B. Abdullah, and W. W. Zailani, Effect of Geopolymer Coating on Mild Steel, Solid State Phenomena. 273 (2018) 175-180

J. Davidovits, Geopolymer chemistry and applications. Institute Geopolymer, France, (2020)

Y. Zhang, J. Zhang, J. Jiang, D. Hou, and J. Zhang, The effect of water molecules on the structure, dynamics, and mechanical properties of sodium aluminosilicate hydrate (NASH) gel: A molecular dynamics study, Construction and Building Materials. 193 (2018) 491-500

J. Temuujin, W. Rickard, M. Lee, and A. van Riessen, Preparation and thermal properties of fire resistant metakaolin-based geopolymer-type coatings, Journal of Non-Crystalline Solids. 357 (2010) 1399-1404

ASTM G31-21, Standard guide for laboratory immersion corrosion testing of metals

J. Zuo, S. Luo, B. Dong, G. Wei, and Y. Wang, Epoxy emulsion modified geopolymer coating for long-term corrosion protection of steel, Case Studies in Construction Materials. 22 (2025) 4252

P. Bhardwaj, R. Gupta, D. Mishra, S. K. Sanghi, S. Verma, and S. S. Amritphale, Corrosion and fire protective behavior of advanced phosphatic geopolymeric coating on mild steel substrate, Silicon. 12 (2020) 487-500

N. Yang, C. S. Das, X. Xue, W. Li, and J.-G. Dai, Geopolymer coating modified with reduced graphene oxide for improving steel corrosion resistance, Construction and Building Materials. 342 (2022) 127942

A. S. Tomar et al., Mechanochemically activated, durable, corrosion protective, advanced geopolymer material, containing gamma- and zinc phosphate, Materials Today Communications. 43 (2025) 111722

J. Han, J. W. Carey, and J. Zhang, Effect of sodium chloride on corrosion of mild steel in CO2saturated brines, Journal of Applied Electrochemistry. 41 (2011) 741-749

S. Hägg Mameng, A. Bergquist, and E. Johansson, Corrosion of stainless steel in sodium chloride brine solutions, NACE - International Corrosion Conference Series 01/01. (2014)

This ePub file was created using machine-generated methods and automated software to convert the source text into an ePub format and may contain formatting inconsistencies from the original version. Formatting may vary depending on the device used.

The original version of this eBook is available on https://www.scientific.net/book/engineering-chemistry-vol-10/978-3-0364-1889-6

Engineering Chemistry, ISSN: 2813-6535, Vol. 10, pp 43-56

doi: 10.4028/p-72XsbZ

© 2025 The Author(s). Published by Trans Tech Publications Ltd, Switzerland.

Submitted:
2024-03-20

Revised:
2025-01-19

Accepted:
2025-02-05

Online:
2025-08-26

Effect of Additional Concentration of ATMP Inhibitor on The Formation of 40% Phosphoric Acid Scale

The original version of this paper is available on https://www.scientific.net/EC.10.43.pdf

Daril Ridho Zuchrillah , Lily Pudjiastuti , Fatima Az Zahra , Hilmy Dzaky Edo Pratama , Indah Asmaul Chusna and Aulia Zalsabila

¹Departement of Industrial Chemical Engineering, Institut Teknologi Sepuluh Nopember, Indonesia

daril@its.ac.id, blily_p@chem.eng@its.ac.id, cazzahra631@gmail.com, dhilmydzakyedop@gmail.com, easmaulchusnaindah@gmail.com, fzalsaa25@gmail.com

Keywords: Phosphoric Acid, ATMP, Scale

Abstract

Calcium sulfate ( ) scale formation during the phosphoric acid ( ) production process presents significant operational challenges. Key variables influencing scale formation include temperature, pressure, stirring speed, and supersaturation. This study aims to evaluate the effect of varying concentrations of ATMP inhibitors on the mass of scale in a phosphoric acid solution and to analyze the composition of the resulting scale. The experimental procedure involved the addition of ATMP inhibitors at different concentrations, while temperature and stirring speed were varied. The solution was circulated through a sample housing for two hours, after which the mass of the formed scale was measured, and X-Ray Fluorescence (XRF) analysis was performed. The optimal concentration of ATMP inhibitors was found to be 9 ppm at a temperature of and a stirring speed of 235 rpm . Results indicated that the composition of the scale produced with ATMP inhibitors was significantly lower than that of samples without inhibitors, with XRF analysis revealing an reduction in levels.

Introduction

The original version of this paper is available on https://www.scientific.net/EC.10.43.pdf

Scale formation is a significant issue commonly found in pipelines. In the phosphoric acid industry, scale formation, particularly from calcium sulphate ( ), poses a serious problem. The accumulation of this scale can lead to the narrowing of the pipeline diameter, which in turn can reduce the pipeline's performance by slowing down the flow rate and impairing heat transfer within the pipe [1]. The formation of scale is influenced by several factors, including temperature changes, supersaturation, concentration changes, and agitation [2].

In the phosphoric acid industry, heat exchangers are used for heating, with steam temperatures of on the shell side and on the tube side, through which phosphoric acid flows. The presence of formed during the initial stages of the hemihydrate reaction, combined with the operating conditions of the heat exchanger at temperatures above , causes supersaturation of the phosphoric acid, leading to the formation of scale crystals [3]. The existence of this scale if it continues will cause disruption of the production process such as narrowing the fluid flow in industrial equipment which results in an increase in temperature and pressure, which can cause pipe rupture [4].

The presence of scale on the heat exchanger is often solved by periodic water cleaning by shutting down the factory production process for 7 to 14 days. This results in high costs and reduces production optimization. Therefore, other alternatives are needed in the form of scale inhibitors to prevent the process of scale formation. There are several kinds of inhibitors commonly used in industry, including inorganic and organic compounds. Many organic compounds used as inhibitors contain phosphates such as polyphosphates, phosphonates, polycarboxylates, aminotris trimethylenephosphonic acid (ATMP), diethylenetriamine pentamethylene phosphonic acid (DTPMP), etc [5].

ATMP is an environmentally friendly organic phosphonate compound used in open water circulating cooling systems, petroleum pipelines and boilers as a scale and corrosion inhibitor [6]. The way these inhibitors work in suppressing the rate of scale growth is by binding and coating scaleforming cations into chelate compounds that will dissolve in water. The inhibitor will then adsorb on the smooth crystal surface and react to form a chelate [7]. According to [8] ATMP performs better than other corrosion inhibitors such as polyacrylic acid (PAA) and polyamino polyether methylenephosphonate (PAPEMP). Of the three inhibitors, ATMP does not require a large dose to achieve inhibition efficiency on scale, which is between . In addition [9] also proved that at a concentration of 25 ppm ATMP has the best performance when compared to diethylenetriamine penta (methylene phosphonic acid) (DTPMP), Phospono Butane Tricarboxylic Acid (PBTC), ethylenediamine tetra (methylene phosphonic acid) (EDTMP) and Hexamethylene-diaminetetra (methylene phosphonic) acid (HDTMP).

In this research, the performance and efficiency of ATMP inhibitor in phosphoric acid has not been known. Therefore, this research was carried out with the aim of determining the minimum scale mass in phosphoric acid solution from the effect of changes in ATMP inhibitor concentration, temperature and stirring speed and knowing the effect of ATMP inhibitor addition on the quality of phosphoric acid solution through XRF analysis of the composition of the crust formed.

Materials and Methods

The original version of this paper is available on https://www.scientific.net/EC.10.43.pdf

The research methodology aims to evaluate the effect of varying concentrations of ATMP inhibitor on the formation of calcium sulphate ( ) scale in a phosphoric acid solution flow system. The study was conducted using a scale formation simulator developed based on the research methodology of[10].

The materials used in this research is aquades, ATMP inhibitors, calcium chloride ( ), sodium sulphate (Na2SO4). The dependent variables include an operating pressure of 1 atm , a solution volume of 500 mL , and a flow rate of . The independent variables consist of ATMP inhibitor concentrations ( , and 11 ppm ), phosphoric acid solution temperatures ( , , and ), and agitation speeds ( , and 623 rpm ). Various tools and materials were utilized in the study, including sandpaper, a storage tank, beaker glasses, an oven, measuring cylinders, a heater, copper pipes, an XRF analysers, pipettes, pumps, heat-resistant hoses, an electric scale, and valves.

Fig. 1 Schematic of the Scale Forming Process Simulator Tool

Fig. 1. Schematic of the Scale Forming Process Simulator Tool

The experimental procedure begins with the preparation of equipment, which consists of two containers: a 500 mL beaker and a 1-liter collection tank. The beaker is used to mix , and the inhibitor solution of ATMP according to the predetermined variables. The sample housing pipe serves as the medium for scale formation, with the flow rate of the sample being controlled using
a valve or faucet on the outlet of the sample pipe. The fluid flow in the collection tank is then recycled back to the beaker using a pump during the 2-hour experiment.

To prepare the 40% phosphoric acid solution, first measure 230 mL of phosphoric acid using a graduated cylinder, then transfer it to the beaker and add distilled water until the total volume reaches 500 mL . Next, to prepare the and mixture, weigh out 9.71 grams of and 12.42 grams of , then add them into the beaker containing the 500 mL phosphoric acid and distilled water mixture. Afterward, turn on the hot plate stirrer to mix the solution until it becomes homogeneous.

Determining Experimental Design Using Minitab. The efficient design and analysis of experiments necessitate the use of Design of Experiment (DOE). The primary objective of DOE is to comprehend the cause-and-effect relationship between input factors (independent variables) and responses (dependent variables) within a system or process. In this research, the ATMP inhibitor concentration, temperature, and stirring speed are considered as input factors, with precipitate weight being the response. In Minitab Software, DOE achieves this by initially creating a response surface design. Subsequently, decisions are made regarding the number of factors to incorporate and the selection of experiment designs.

Fig. 2. Display Response Surface Design on Minitab

Fig. 2. Display Response Surface Design on Minitab

This study employs Central Composite Design (CCD) for experimental analysis. On the create response surface design menu, CCD is selected by entering the number of continuous factors 3 . This is because there are 3 factors tested in this research, namely the concentration of inhibitors in ppm, temperature, and stirring speed in rpm. After selecting the design type, then click the "Designs" button, then choose how much research will be done.

Fig. 3. Multiple Response Surface Design Experiment Options on Minitab

Fig. 3. Multiple Response Surface Design Experiment Options on Minitab

Then, click "OK" and return to the create response surface design menu. Then, click the "Factors" button to enter the upper and lower limits of the variables to be experimented, Then, click "OK" again.

Fig. 4. Display of Menu Factors in Create Response Surface Design in Minitab

Fig. 4. Display of Menu Factors in Create Response Surface Design in Minitab

Then, go back to the create response surface design menu, after that select "Designs" and select center points and alpha values according to the default.

Fig. 5. Display of Center Points and Alpha Value Selection on Minitab

Fig. 5. Display of Center Points and Alpha Value Selection on Minitab

After clicking "OK", the results of the combination of experimental designs will appear on each factor. Then, add the response column as a column for input of scale deposits after the experiment. In the results of the experimental design using the RSM method, it produces 2 new variables in each factor. In the factor of increasing the concentration of ATMP inhibitors there is an addition of variables 1 and 11 ppm , in the temperature factor there is an addition of variables and and the stirring speed factor there is an addition of variables namely 140 and 623 rpm . In the RSM method, the response variable is modeled as a function of the input variable, and the goal is to find the optimal input value that maximizes or minimizes the response variable. The upper and lower bounds of response variables are important because they determine the range of values that response variables can take, and they can be used to identify outliers or unusual observations in data [11] [12].

Fig. 6. Results of Experimental Design Display on Minitab

Fig. 6. Results of Experimental Design Display on Minitab

The preparation of the ATMP inhibitor solution involves creating solutions of ATMP inhibitors at concentrations of , and 11 ppm . This is achieved by preparing a mother solution containing 100 ppm ATMP, wherein ATMP inhibitors are dissolved in a quantity of 0.2 ml within a volume of 1000 ml of aquades. This observation was made with five different ATMP inhibitor concentration treatments. The dilution of inhibitors of 11 ppm concentration to , and 9 ppm refers to the dilution formula.

In this research, 9.71 grams of and 12.42 grams of were put into a beaker until both compounds were homogeneous by adjusting the temperature and stirring speed that had been set, then adding ATMP inhibitors according to the variables. If the heater has reached the set temperature, open the flow valve to the sample housing. The sample house is a component for which scale deposition of calcium sulfate ( ) is expected. The flow velocity leaves the sample exactly according to the design, which is . The flow that has passed through the sample house will be accommodated in a reservoir which will then be recycled back to the beaker glass.

After two hours of experimentation, the tap to the channel of the sample house was closed. An hour later, the sample house is taken and dried in the oven at a temperature of for eight hours. Inside the sample housing, the solution begins to react to form a crust. The difference between the mass of the sample house and the crust in the dry state minus the mass of the sample house without scale is the mass of the crust itself. With the same treatment, experiments continue to be carried out according to the variables of ATMP inhibitor concentration, solution temperature, and stirring speed.

Determination of Minitab Optimization Results involves incorporating the recorded scale deposit results into the Minitab response column, conducting surface design analysis, creating contour plots, and understanding the optimization achieved by the response optimizer.

Fig. 7. Minitab Menu Display to Know the Results of the Research Analysis

Fig. 7. Minitab Menu Display to Know the Results of the Research Analysis

Fig. 8. Minitab Menu Display to Know the Contour Plot Resulting from the Experiment

Fig. 8. Minitab Menu Display to Know the Contour Plot Resulting from the Experiment

Fig. 9. Minitab Menu Display to Know the Optimization Response Resulting from the Experiment

Fig. 9. Minitab Menu Display to Know the Optimization Response Resulting from the Experiment

Analysis using XRF is performed based on the identification and enumeration of X-ray characteristics that occur from photoelectric effect events. Photoelectric effects occur because electrons in the target atom (sample) are exposed to a high-energy beam (gamma radiation, X-rays). If the energy of the beam is higher than the binding energy of the electrons in the K, L, or M orbits of the target atom, then the electrons of the target atom will exit their orbits. Thus, the target atom will experience an electron vacuum. This electron void will be filled by electrons from the outer orbitals followed by the release of energy in the form of X-rays [13].

The X-rays produced are a combination of a continuous spectrum and a certain energy spectrum (discreet) derived from the target material that is pounded by electrons. The type of discreet spectrum that occurs depends on the transfer of electrons that occur in the atoms of the material. This spectrum is known as the characteristic X-ray spectrum. XRF spectrometry utilizes X-rays emitted by the material which are then captured by the detector to analyze the elemental content in the material. The material analyzed can be massive solids, pellets, or powders. Elemental analysis is carried out qualitatively and quantitatively. Qualitative analysis analyzes the type of element contained in the material and quantitative analysis is performed to determine the concentration of elements in the material. X-rays produced from events such as those mentioned above are captured by a Silicon Lithium (SiLi) semiconductor detector [13].

Result and Discussion

The original version of this paper is available on https://www.scientific.net/EC.10.43.pdf

The solubility of in phosphoric acid is influenced by various factors such as acidity, the presence of other solutes, and temperature [14]. mentioned that the solubility of in water with a temperature of is about . However, after a trial with the same concentration of in phosphoric acid solution obtained by mixing and in a ratio of , it is still soluble in water. So in this experiment, the concentration of was increased to .

The result of MINITAB design to find the optimization of solution with the addition of ATMP inhibitor, temperature of , and rotating speed of 238,381 , and 525 rpm , first running the experimental variables on Minitab software. This is done to determine the design of experiment (DOE). DOE in RSM serves to explore the relationship between several explanatory variables and one or more response variables. The main objective of RSM is to develop, improve, and optimize the process of determining the optimum formulation [15]. In this case, the variables of concentration, temperature and rotating speed are the factors that will be experimented with to produce a response in the form of sediment weight.

After running DOE on Minitab software, new upper and lower limits were obtained for each factor. The concentration factor obtained an upper limit of 11 ppm and a lower limit of 1 ppm . Then the temperature factor obtained an upper limit of and a lower limit of . While the stirring speed factor obtained an upper limit of 623 rpm and a lower limit of 139 rpm .

The upper and lower limits obtained serve to provide an upper limit referring to the maximum permissible value for the factor being tested. Factor values above the upper limit may not affect the response or may even produce undesirable results. For example, if the factor being tested is temperature in a chemistry experiment, the upper limit may indicate the maximum temperature at which it is safe to carry out the experiment. The lower limit, on the other hand, refers to the minimum permissible value for the factor being tested. Factor values below the lower limit may not give relevant results or may cause uncertainty in the experimental results. Using the previous example, a lower limit for temperature could indicate the minimum temperature required for a chemical reaction to occur [16].

After obtaining the experimental design from Minitab software, an experiment was conducted by circulating solution in the pipe (sample house) for 2 hours. The experiment was conducted to determine the amount of scale formed by the factors of ATMP inhibitor addition, temperature treatment and stirring speed. Then, a response was obtained in the form of the weight of the scale deposits formed on the pipe (sample house). The results of this research are shown in Figure 10. and Figure 11. The resulting scale deposits were then analysed by XRF which are presented in Table 9 and Table 10.

The plot of the response surface method (RSM) optimization results was conducted to show the effect of scale mass formation in phosphoric acid solution caused by the relationship between concentration, temperature, and stirring speed. The plot used was a contour plot containing the predictors on the x and y axes. Contour lines connect points that have the same response value and colored contours show the range of response values produced.

After that we know about contour plot of concentration vs temperature. In industry, formation is a common event that can occur especially in heat exchanger equipment. This formation can potentially occur in piping systems that are passed by solutions with high concentrations of calcium sulphate. Several factors can influence the formation of calcium sulphate scale such as temperature and concentration. The following contour plot shows the effect of these two factors on scale mass formation:

Fig. 10. Contour Plot of Factor Relationship of ATMP Inhibitor Concentration and Temperature on Scale Mass Response

Fig. 10. Contour Plot of Factor Relationship of ATMP Inhibitor Concentration and Temperature on Scale Mass Response

The contour plot above shows the results of the combination of factors between ATMP inhibitor concentration and temperature on scale formation. The results of the magnitude of the response to temperature conditions and the addition of concentrations are described by colour. The more intense the green colour indicates that more scale is produced. In the contour plot above, the most intense green colour indicates a response result of more than 5 . While the smallest response is produced with a weight of less than 2 grams.

The combination of high temperature with low concentration produces a large crust mass response of more than 5 grams. The response results changed as the inhibitor concentration and temperature increased. This condition is due to the increase in solution temperature ( ), the formation of more scale. The increase in temperature will cause the reaction speed to increase which causes a decrease in induction time at saturation level conditions [17].

The addition of ATMP inhibitor concentration affects the formation of scale mass. In Figure 4.1, the countur plot shows that at high temperature conditions there is a decrease in scale mass along with the increase in ATMP inhibitor concentration. The effect of adding ATMP inhibitor additives can prevent scale formation when added at high concentrations. The efficiency of ATMP inhibitors has a "threshold effect" which has a certain concentration limit in its performance [18]. In this research, the "threshold effect" has not been obtained, so further experiments are needed to reach the threshold in phosphoric acid solution.

The contour plot depicts the relationship between concentration and stirring speed. The outcomes illustrating the extent of the response to variations in rotation speed and added concentration are represented through color-coded plots. The more intense the green colour indicates that more crust is produced. Conversely, the lighter the green colour and the appearance of blue areas indicate that the crust response is less, in the contour plot above it is shown that the smallest precipitate weight produced is less than 3 grams and the largest is more than 5.5 grams. In the contour plot above, the most intense green colour indicates the response results are more than 5 . Stirring speed is included in the factors that affect the formation of calcium sulfate crust. As Figure 10. shows, the largest scale formation occurs in the stirring speed range of 250 rpm to 580 rpm with low ATMP inhibitor concentration. However, in this combination of factors, it can be seen that the stirring speed does not have much effect on the crust mass results. The increase in stirring speed is in line with the increase in crust mass, agitation can accelerate the reaction so that the formation or growth of crystals becomes more [19]. This ability of ATMP inhibitor at high concentrations significantly inhibits the formation of calcium sulphate scale.

Fig.11. Contour Plot of the Relationship between ATMP Inhibitor Concentration and Stirring Speed to Mass Response

Fig.11. Contour Plot of the Relationship between ATMP Inhibitor Concentration and Stirring Speed to Mass Response

The effect of adding inhibitors can prevent crystal formation from the beginning, where at the secondary nucleation stage small crystals that begin to form will be prevented or inhibited by the ability of ATMP inhibitors. This prevention process causes small crystals of about in size to be difficult to form towards larger crystals [20].

The results of condition optimization using Response Surface Methodology (RSM), widely applied for data optimization, involve a mathematical and statistical model. This model is utilized to analyze situations in which multiple variables impact the response variable. This method is used to model and analyses a response y that is influenced by several independent variables or factors x as optimization of the response [21]. Based on the research results, the crust mass response has the lowest value of 1.37 grams and the largest value of 5.67 grams. The results of the research optimisation using the RSM method are shown in the figure below.

Figure 12. Process Optimisation Results on Scale Mass Formation

Figure 12. Figure 12. Process Optimisation Results on Scale Mass Formation

The optimisation result in Figure 4.3 is an optimal result of the response optimisation process determined by statistical analysis. The crust mass response optimisation value of 1.9 grams is obtained from the combination of concentration, temperature, and stirring speed factors of 9 ppm , , and 235 rpm respectively at certain predetermined limits. In addition to these three factors, scale formation is influenced by several main factors including changes in reservoir conditions, reservoir pressure and temperature changes, mixing of two types of water that have incompatible mineral composition, supersaturation, evaporation due to changes in concentration, stirring (agitation, influence of turbulence), contact time between scale and pipe surface and changes in water pH [20].

The low scale mass value is in accordance with the influence of the three factors under conditions of high inhibitor concentration with low temperature and rpm. Inhibitors function as inhibitors of crystal formation by slowing the rate of formation, increasing heterogeneous nucleation control and stabilising scale deposits. As for calcium sulphate, it has a high solubility under temperature conditions of , so it tends to produce a low scale mass [22]. While the mass of crust formed is small at low stirring speeds due to the acceleration of reactions between compounds. [19].

Results of Scale Mass Decrease upon the Addition of Inhibitor Concentration. This study investigates the reduction in scale mass in response to the addition of ATMP inhibitor concentration, temperature, and stirring speed. The results in this research were also optimized using Response Surface Methodology (RSM). In general, the value of inhibitor concentration will increase the ability to inhibit scale formation. Thus, the scale formation process will decrease along with the change in ATMP inhibitor concentration. The graph below will show the results of the scale mass of each concentration with a fixed temperature and stirring speed.

Fig. 13. Effect of Concentration on Scale Formation

Fig. 13. Effect of Concentration on Scale Formation

The graph above is a presentation of the concentration of , and 10 ppm under conditions of temperature and stirring speed 381 rpm with a scale mass of 6.7 grams; 5.4 grams; and 4.2 grams which shows the results of the trend of decreasing scale mass from the smallest to the largest concentration. ATMP inhibitors are included in the inorganic polyphosphate additive which is a non-crystallised inorganic solid, this substance has advantages in its slower solubility process and can provide the required concentration for a long period of time [23]. Other literature also states that the performance of additives can capture ions so that crystal formation is inhibited, so that the reaction rate of scale formation can be inhibited and suppress the formation of scale [20].

Characterization of dry precipitate results with XRF. The analysis conducted using the XRF instrument aims to determine the composition of a solid sample. The results of the crust sample analyzed by XRF are samples obtained from the results of the research using optimization conditions, namely the addition of 9 ppm of ATMP inhibitor at and a rotation speed of 235 rpm . To measure the performance of the inhibitor, an experiment was also conducted without the use of inhibitors. Both were carried out using the same temperature operating conditions at and a rotation speed of 381 rpm . After XRF analysis, the composition of the scale is displayed in the mass fraction of elements or oxide compounds. The results of the analysis of the composition of scale deposits in phosphoric acid solution are shown in Table 1.

Table 1. Compound Composition Analysis Results of Precipitate Using XRF Instrument

Component | Mass Fraction (%)
| Using Inhibitors | without Inhibitor
P₂O₅ | 39,45 | 35,65
SO₃ | 27,75 | 28,6
CaO | 32 | 35

Table 1. shows the XRF analysis results of the scale deposits found in the research. The chemical components produced by , and . The presence of is because the scale was formed in phosphoric acid solution. Then, the large content of CaO and proves that the crust formed is calcium sulphate ( ) crust. The formation of scale is shown in the following reaction [24]:

The table also shows the difference in the amount of CaO and content using inhibitors and without using inhibitors. In the research using ATMP inhibitor, the CaO contained in the crust was while that without using inhibitor was . While the content in the crust in the research using the inhibitor was and the research without using the inhibitor was . These results show that the research using ATMP inhibitor is less than the one without inhibitor. These results also prove that the ATMP inhibitor successfully reduced the CaO and content in the scale. The percentages of CaO and obtained were then calculated using the stoichiometric method to find the mass percent of the crust. The results of the scale calculation are shown in Table 2. below:

Table 2. Comparison Results of Mass Fraction Using Inhibitor and Without Using Inhibitor

Using Inhibitor | Without Inhibitor
75% | 83%

In this research ATMP works to reduce scale. Table 4.2 shows that ATMP inhibitor can reduce the scale mass by . This is because ATMP can inhibit the formation of calcium sulphate scale through its chelation and lattice distortion capabilities, which prevent scale formation. ATMP can also be used in mixture with other scale inhibitors to improve its inhibition performance [25]. The performance of ATMP in preventing scale formation is by binding ions present in solution. This was shown by [26] with the following reaction:

Fig. 14. The performance of ATMP in preventing scale

Fig. 14. The performance of ATMP in preventing scale

In the above reaction M is a divalent cation. In this research works as a divalent cation bound by ATMP as a scale inhibitor. This prevents the reaction between and , so that scale does not form.

The addition of ATMP in this research did not reduce the quality of phosphoric acid. This is shown by the content of when using the inhibitor, which is greater than without using the inhibitor which is . The increase in the percentage of the mass fraction is because ATMP can have an effect on increasing the phosphorus content of a substance [27].

Result and Discussion

The original version of this paper is available on https://www.scientific.net/EC.10.43.pdf

The results indicate that the use of ATMP as an inhibitor effectively reduces the formation of scale under the tested conditions. The observed minimum scale mass of 1.9 grams at an ATMP concentration of 9 ppm suggests that even low concentrations of this inhibitor can significantly reduce scale formation. This finding is consistent with previous [28], which reported similar reductions in scale formation when using phosphonate-based inhibitors.

Moreover, the XRF analysis showing an decrease in levels further supports the effectiveness of ATMP in mitigating scale formation. This reduction not only underscores the role of the inhibitor but also highlights its potential to improve operational efficiency in systems prone to scaling issues. Comparable studies [29] have documented similar efficacy with other inhibitors, suggesting that ATMP could be a viable option for industries dealing with scale deposits.

In conclusion, integrating ATMP inhibitors into water treatment processes could lead to significant improvements in efficiency and reduced maintenance costs associated with scaling problems.

References

The original version of this paper is available on https://www.scientific.net/EC.10.43.pdf

W. A. Putranto and S. Khaeruman, "Pengaruh Laju Aliran, Suhu Dan Aditif Asam Tartrat ( ) Terhadap Morfologi Dan Fasa Kristal Pada Kerak Kalsium Karbonat ( )," Momentum, vol. 16, no. 2, pp. 105-110, 2020.

F. Fatra and J. Suwignyo, "Analisa Pengaruh Penambahan Asam Tartrat Terhadap Pembentukan Kerak Di Dalam Pipa Pengeboran Minyak Bumi," 2020.

A. Zeino, M. Albakri, M. Khaled, and M. Zarzour, "Comparative study of the synergistic effect of ATMP and DTPMPA on CaSO4 scale inhibition and evaluation of induction time effect," Journal of Water Process Engineering, vol. 21, pp. 1-8, Feb. 2018, doi: 10.1016/j.jwpe.2017.11.013.

F. Fatra and J. Suwignyo, "Analisa Pengaruh Penambahan Asam Tartrat Terhadap Pembentukan Kerak Di Dalam Pipa Pengeboran Minyak Bumi," Journal of Automotive Technology Vocational Education, vol. 1, no. 2, pp. 1-8, Oct. 2020, doi: 10.31316/JATVE.V1I2.991.

M. F. Mady, A. H. Karaly, S. Abdel-Azeim, I. A. Hussein, M. A. Kelland, and A. Younis, "Phosphonated Lower-Molecular-Weight Polyethyleneimines as Oilfield Scale Inhibitors: An Experimental and Theoretical Study," Ind Eng Chem Res, vol. 61, no. 27, pp. 9586-9599, Jul. 2022, doi: 10.1021/acs.iecr.2c01730.

F. Ivušić, V. Alar, and H. Otmačić Ćurković, "Aminotris(Methylenephosphonic acid) and sodium gluconate as inhibitors of carbon steel corrosion in solution," International Journal of Corrosion and Scale Inhibition, vol. 9, no. 4, pp. 1390-1401, 2020, doi: 10.17675/2305-6894-2020-9-4-12.

M. A. Jafar Mazumder, "A review of green scale inhibitors: Process, types, mechanism and properties," Oct. 01, 2020, MDPI AG. doi: 10.3390/coatings10100928.

Y. Tang, W. Yang, X. Yin, Y. Liu, P. Yin, and J. Wang, "Investigation of CaCO3 scale inhibition by PAA, ATMP and PAPEMP," Desalination, vol. 228, no. 1-3, pp. 55-60, Aug. 2008, doi: 10.1016/j.desal.2007.08.006.

A. Khormali, G. Bahlakeh, I. Struchkov, and Y. Kazemzadeh, "Increasing inhibition performance of simultaneous precipitation of calcium and strontium sulfate scales using a new inhibitor - Laboratory and field application," J Pet Sci Eng, vol. 202, Jul. 2021, doi: 10.1016/j.petrol.2021.108589.

A. D. Nur Rahmadyo, D. Cahayandari, and S. Rahardjo, "Perbandingan Analisa Kinetika Reaksi Pembentukan Kerak Menggunakan Persamaan Arrhenius Dan Analisa Differensial Scanning Calorimetry (DSC)," pp. 64-71, 2017.

K. Anwar, F. Istiqamah, S. H. Program, S. Farmasi, L. Mangkurat, and K. Selatan Indonesia, "Optimasi Suhu dan Waktu Ekstraksi Akar Pasak Bumi (Eurycoma longifolia jack.) Menggunakan Metode RSM (response surface methodology) dengan Pelarut Etanol 70%," 2021. [Online]. Available:

H. Nurcahyadi, "Analisis Regresi Pada Data Outlier Dengan Menggunakan Least Trimmed Square (LTS) Dan Mm-Estimasi," 2010.

M. Munasir, T. Triwikantoro, M. Zainuri, and D. Darminto, "Uji XRD dan XRF pada Bahan Meneral (Batuan dan Pasir) Sebagai Sumber Material Cerdas (CaCO3 dan SiO2)," Jurnal Penelitian Fisika dan Aplikasinya (JPFA), vol. 2, no. 1, p. 20, 2012, doi: 10.26740/jpfa.v2n1.p20-29.

D. R., & H. W. M. (Eds.) Lide, CRC Handbook of Chemistry and Physics, 99th ed. CRC Press, 2018.

R. Trihaditia, M. Syamsiah, A. Awaliyah, S. T. Mt, S. Pd, and M. Si, "Penentuan Formulasi Optimum Pembuatan Cookies Dari Bekatul Padi Pandanwangi Dengan Penambahan Tepung Terigu Menggunakan Metode RSM (Response Surface Method)," vol. 8, no. 2, 2018.

Sectlon A and 0 Helene, "Instruments &Mm In Phvsics Research Determination of upper and lower limits combining different experimental results," 1997.

S. Muryanto et al., "Pengaruh Temperatur Terhadap Pembentukan Kerak Gipsum Dalam Pipa," vol. 16, no. 4, pp. 2-6, 2012.

Y. Tang, W. Yang, X. Yin, Y. Liu, P. Yin, and J. Wang, "Investigation of CaCO3 scale inhibition by PAA, ATMP and PAPEMP," Desalination, vol. 228, no. 1-3, pp. 55-60, 2008, doi: 10.1016/j.desal.2007.08.006.

G.A. Fachriansyah and R. Allifyanto, "Pengaruh Inhibitor Magnesium Klorit Dan Kalsium Klorit Dalam Pembentukan Kristal Barium Sulfat," 2022.

S. Rahardjo, "Pembentukan dan Pengendalian Kerak Mineral di Dalam Pipa,"Universitas Muhammadiyah Semarang (Unimus), 2020.

M. A. Octaviani, D. Retno, S. Dewi, and L. J. Asrini, "Optimasi Faktor Yang Berpengaruh Pada Kualitas Lilin Di Ud.X Dengan Metode Response Surface,"Jurnal Ilmiah Widya Teknik, vol. 16, pp. 29-38, 2017.

D. Buhani and P. Suharso, Penanggulangan Kerak Edisi II, vol. 4, no. 1. 2015.

V. Restya, "Analisis Penanggulangan Pertumbuhan Scale Dengan Metode Injeksi Scale Inhibitor Secara Continue Di Surface Facility Pada Lapangan Minyak VR," Tugas Akhir, pp. 1-10, 2019.

K. Tanaka, Y. Sakai, Y. Ishii, Y. Yokobayashi, S. Sakaida, and M. Konno, "An experimental study on the conversion of CaO to CaSO 4 during diesel particulate lter regeneration," 2023, doi: 10.21203/rs.3.rs-2546442/v1.

A. Zeino, M. Albakri, M. Khaled, and M. Zarzour, "Comparative study of the synergistic effect of ATMP and DTPMPA on CaSO4 scale inhibition and evaluation of induction time effect," Journal of Water Process Engineering, vol. 21, pp. 1-8, Feb. 2018, doi: 10.1016/j.jwpe.2017.11.013.

V. Tantayakom, H. S. Fogler, F. F. De Moraes, M. Bualuang, S. Chavadej, and P. Malakul, "Study of Ca-ATMP Precipitation in the Presence of Magnesium Ion," Langmuir, vol. 20, no. 6, pp. 2220-2226, Mar. 2004, doi: 10.1021/la0358318.

N. Huang, Z. bin Xu, W. L. Wang, Q. Wang, Q. Y. Wu, and H. Y. Hu, "Elimination of amino trimethylene phosphonic acid (ATMP) antiscalant in reverse osmosis concentrate using ozone: Anti-precipitation property changes and phosphorus removal," Chemosphere, vol. 291, Mar. 2022, doi: 10.1016/j.chemosphere.2021.133027.

T. A. Hoang, H. M. Ang, and A. L. Rohl, "Investigation into the effects of phosphonic inhibitors on the formation of calcium sulfate scales," Desalination Water Treat, vol. 29, no. 1-3, pp. 294-301, 2011, doi: 10.5004/dwt.2011.2188.

M. A. Jafar Mazumder, "A review of green scale inhibitors: Process, types, mechanism and properties," Oct. 01, 2020, MDPI AG. doi: 10.3390/coatings10100928.

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Keywords Index

A

Atmp Effect of Additional Concentration of ATMP Inhibitor on The Formation of 40% Phosphoric Acid Scale

B

Biogas; Electricity Efficiency; Pome Efficiency of Industrial-Scale Biogas Application from Palm Oil Mill Effluent (POME) as a Renewable Energy Source: A Case Study at PT AMP

Black Soldier Fly Synthesis of Pour Point Depressant from Black Soldier Fly Maggot Oil

C

Carboxylic Acids Zwitterionic Buffering Agent as an Alternative to Improve Carboxylic Acid Extraction Performance with 1-Heptanol Solvent

Coating The Potential of Fly Ash Based Geopolymer Coatings for Steel Corrosion Protection

Corrosion The Potential of Fly Ash Based Geopolymer Coatings for Steel Corrosion Protection

Crude Oil Synthesis of Pour Point Depressant from Black Soldier Fly Maggot Oil

E

Epps Biological Buffer Zwitterionic Buffering Agent as an Alternative to Improve Carboxylic Acid Extraction Performance with 1-Heptanol Solvent

Esterification Synthesis of Pour Point Depressant from Black Soldier Fly Maggot Oil

F

Fly-ash Based The Potential of Fly Ash Based Geopolymer Coatings for Steel Corrosion Protection

G

Geopolymer The Potential of Fly Ash Based Geopolymer Coatings for Steel Corrosion Protection

I

Immersion The Potential of Fly Ash Based Geopolymer Coatings for Steel Corrosion Protection

L

Liquid-liquid Extraction Zwitterionic Buffering Agent as an Alternative to Improve Carboxylic Acid Extraction Performance with 1-Heptanol Solvent

M

Maggot Oil Synthesis of Pour Point Depressant from Black Soldier Fly Maggot Oil

P

Paraffin Synthesis of Pour Point Depressant from Black Soldier Fly Maggot Oil

Phosphoric Acid Effect of Additional Concentration of ATMP Inhibitor on The Formation of 40% Phosphoric Acid Scale

Pour Point Depressant Synthesis of Pour Point Depressant from Black Soldier Fly Maggot Oil

S

Scale Effect of Additional Concentration of ATMP Inhibitor on The Formation of 40% Phosphoric Acid Scale

Silicon Carbide; Threading Screw Dislocation; Basal Plane Dislocation; Non-destructive Characterization; Koh Etching; X-ray Topography Characterization of Dislocations in 4H-SiC

Authors Index

A

Altway, S. Zwitterionic Buffering Agent as an Alternative to Improve Carboxylic Acid Extraction Performance with 1-Heptanol Solvent

Ardinal, A. Efficiency of Industrial-Scale Biogas Application from Palm Oil Mill Effluent (POME) as a Renewable Energy Source: A Case Study at PT AMP

B

Beki, A. Zwitterionic Buffering Agent as an Alternative to Improve Carboxylic Acid Extraction Performance with 1-Heptanol Solvent

Berghuis, N. Synthesis of Pour Point Depressant from Black Soldier Fly Maggot Oil

C

Chusna, I. Effect of Additional Concentration of ATMP Inhibitor on The Formation of 40% Phosphoric Acid Scale

G

Gao, C. Characterization of Dislocations in 4H-SiC

H

Halifah, J. Synthesis of Pour Point Depressant from Black Soldier Fly Maggot Oil

I

Iswari, K. Efficiency of Industrial-Scale Biogas Application from Palm Oil Mill Effluent (POME) as a Renewable Energy Source: A Case Study at PT AMP

L

Lubis, M. Synthesis of Pour Point Depressant from Black Soldier Fly Maggot Oil

M

Marlina, L. Efficiency of Industrial-Scale Biogas Application from Palm Oil Mill Effluent (POME) as a Renewable Energy Source: A Case Study at PT AMP

P

Peng, H. Characterization of Dislocations in 4H-SiC

Pramana, A. Synthesis of Pour Point Depressant from Black Soldier Fly Maggot Oil

Pratama, H. Effect of Additional Concentration of ATMP Inhibitor on The Formation of 40% Phosphoric Acid Scale

Pudjiastuti, L. Effect of Additional Concentration of ATMP Inhibitor on The Formation of 40% Phosphoric Acid Scale

Putra, D. Efficiency of Industrial-Scale Biogas Application from Palm Oil Mill Effluent (POME) as a Renewable Energy Source: A Case Study at PT AMP

Putri, S. Zwitterionic Buffering Agent as an Alternative to Improve Carboxylic Acid Extraction Performance with 1-Heptanol Solvent

R

Rabat, N. The Potential of Fly Ash Based Geopolymer Coatings for Steel Corrosion Protection

Rahayu, S. Zwitterionic Buffering Agent as an Alternative to Improve Carboxylic Acid Extraction Performance with 1-Heptanol Solvent

S

Sufian, S. The Potential of Fly Ash Based Geopolymer Coatings for Steel Corrosion Protection

Suprihatin, S. Zwitterionic Buffering Agent as an Alternative to Improve Carboxylic Acid Extraction Performance with 1-Heptanol Solvent

Sy, S. Efficiency of Industrial-Scale Biogas Application from Palm Oil Mill Effluent (POME) as a Renewable Energy Source: A Case Study at PT AMP

Y

Yaakob, S. The Potential of Fly Ash Based Geopolymer Coatings for Steel Corrosion Protection

Z

Zahra, F. Effect of Additional Concentration of ATMP Inhibitor on The Formation of 40% Phosphoric Acid Scale

Zalsabila, A. Effect of Additional Concentration of ATMP Inhibitor on The Formation of 40% Phosphoric Acid Scale

Zhu, C. Characterization of Dislocations in 4H-SiC

Zuchrillah, D. Effect of Additional Concentration of ATMP Inhibitor on The Formation of 40% Phosphoric Acid Scale