Engineering Chemistry Vol. 10

Abstract: Accurate characterization of dislocations is crucial for optimizing the performance of SiC-based 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 4H-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 X-ray topograph are not recognizable in KOH etching image. In addition, some 60° 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.

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 1%. 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.

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 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 133736 Nm³ respectively, and an average power produced of 159.530, 153.168, and 160.161 MWh 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 15.20 %, 22.49%, and 20.96%. Based on calculations, it is found that the use of methane capture or biogas technology 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.

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 29% to 32%, 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 24°C from the original 39°C. Characterization using FTIR testing successfully revealed C-O vibrations (ester groups) at the wave number range of 1158 – 1155 cm^-1 while eliminating O-H 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 87.71%. Keywords: Crude Oil, Esterification, Pour Point Depressant, Maggot, Paraffin, Pour Point.

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 3.5 wt% NaCl solution for immersion periods of 1, 7, 14, 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 3mm 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 0.112 mm/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.

Abstract: Calcium sulfate (CaSO₄) scale formation during the phosphoric acid (H₃PO₄) 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 CaSO₄ scale in a 40% 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 40°C and a stirring speed of 235 rpm. Results indicated that the composition of the CaSO₄ scale produced with ATMP inhibitors was significantly lower than that of samples without inhibitors, with XRF analysis revealing an 8% reduction in CaSO₄ levels