Key Engineering Materials Vols. 594-595

Abstract: The objective of this study is to evaluate the performance of turbidity removal in water by using Okra (Abelmoschus esculentus) as natural coagulant. The coagulation active agent in various Okra sections was extracted with distilled water and NaCl 1.0 M solutions. Synthetic water containing kaolin with turbidity of 55 NTU was used as water source in this study. The result shows that Okra seed that extracted both with distilled water and NaCl 1.0 N solution has the potential advantage as natural coagulant for turbidity removal in comparison with other sections of the plant. However, the seed is not economically feasible to be used as coagulant. The dried Okras leaf that commonly considered as waste material could be proposed as an alternative coagulant in water treatment process, due to its similarity in coagulation behaviour with Okras seed. FTIR analysis on leaf shows that chemical functional groups in protein were significantly removed after extraction with distilled water and NaCl 1.0 N solution. The result indicated a strong correlation between the protein content and turbidity removal efficiency, which eventually suggest that the protein in Okra could potentially be an active agent in coagulation process.

Abstract: The present study aimed to characterize the agricultural residues of sugarcane bagasse {SB} and pineapple core {PC} for the use in immobilization of Lactobacillus rhamnosus NRRL 442. Using Standard Official Methods, SB and PC were found to contain approximately equal amount of nutrition content. The nutrition contents found include: 2.7-2.8 % of protein, 9.8-10 % of crude fiber, and 0.3-0.5 % of fat. On the other hand, SB demonstrated relatively higher solution holding capacity of 9.42 ± 2.3 g/g dry size sample than that of 6.04 ± 2.1 g/g dry size sample in PC. Under screening electron microscope, the fiber of SB has a flat and even surface; in contrast, the fiber of PC has a rough and overlapping surface which may promote the attachment or cell holding capacity during the immobilization process. However, the viability tests after cells immobilization have shown that SB provided higher cell survivability of 93.6 % than that of 64.1% in PC. These result highlighted the greater role of solution holding capacity of cellulose in ensuring a better cell survivability after immobilization process. As conclusion, this study showed the near future potentiality of SB and PC as immobilization carriers for Lactobacillus rhamnosus NRRL 442. It may substitutes proportionally of raw materials and be functional feed for ruminant.

Abstract: Two series of oil palm empty fruit bunch-grafted-poly (acrylic acid-co-acrylamide) [OPEFB-g-P(AA-co-AA slow release fertilizer hydrogels (SRFHs) were prepared via two different techniques namely double dryings of hydrogel (T1) and in situ intercalated urea (T2). Fourier Transform Infrared (FTIR) spectroscopy spectra showed-OH of OPEFB successfully grafted within P(AA-co-AAm) in T1 and T2. Water retention test of red okra plant (abelmoschus escule) and plant growth of rose balsam plant (impatiens balsamina) had showed that no biuret production has occurred in T2 and is more convenient in term of economic production as it requires only one drying process.

Abstract: The objective of this research is to synthesize the microporous activated carbon and test its applicability for CO₂ gas capture. In this study, coconut shell-based and commercial activated carbon is used as the solid adsorbent. Based on the findings, it shows that the gas adsorption capacity is correlated to the total surface area of the materials. In addition, reduction in the adsorption capacity with respect to temperature proves that the physisorption process is dominant. Higher carbon dioxide (CO₂) adsorption capacity in comparison to nitrogen (N₂) capacity contributes to higher CO₂/N₂ selectivity, and confirms its applicability in the post-combustion process. Utilization of abundance agricultural wastes and one-step physical activation process is attractive as it promotes a cleaner pathway for activated carbon production, and simultaneously, reduces the total operating cost.

Abstract: The objective of this research was to study the effects of co-pigmentation on the colour display and stability of Butterfly Pea extracts with plant extracts under different pH. The scopes of the work focus on the effect on co-pigmentation of the Cinnamon, Cumin and Turmeric extract on the colour display. The effects on colour enhancement and the stability of Butterfly Pea extract were evaluated. LC/MS/MS analysis shows that the anthocyanin in Butterfly Pea is highly acylated and therefore, is stable due to intramolecular copigmentation. The flavonoids content in Cinnamon extract was identified as Cinnamtannin B₁ (m/z 864.7, MW 864.7156) while in_. Cumin extract, Apigenin 7-galacturonylglucoside (m/z 609.409, MW 608.524) and Luteolin 7-digalacturonide-4-glucoside (m/z 625.376, MW 624.376) were presented. Dimethoxycurcumin (m/z 394.2, MW 394.0134 and m/z 313.0, MW 312.975) was identified in Turmeric extract. Turmeric was suggested as the best copigment for Butterfly Pea since it showed the highest hyperchromic shift (61.41%), followed by Cinnamon extract (17.04%) and Cumin extract (16.08%).

Abstract: C0-HA composite produced by simple electroless deposition method was studied. From the particle size analysis by Malvern particles analyzer its shows that 19% increment in average of the particle size powder increase after the electroless process with higher cobalt (II) chloride and reduction agent concentration. By EDX and XR-D analysis it was confirmed that cobalt metal was deposited onto HA and contribute to uniform distribution in morphologies by SEM analysis. The Vickers hardness result of up to 430HV was achieved after sintering process at 1250°C. The experimental results demonstrated that the Co-HA powder was successfully prepared by using this method and provide distinct advantages such as uniformity of deposition at lower cost and simple process.

Abstract: Co-HA composite produced using electroless deposition without conventional sensitization and activation treatment was studied with varying sintering temperature (1100°C, 1200°C and 1250°C). The particles size, bulk density, porosity, hardness measurements and the flexural strength are performed in order to find the optimum sintering temperature. After the electroless process for 1 H, the particle size of HA increase to 3.9% and finally the value bulk density percentage of 93.08%, percentage porosity of 6.89%, hardness value of 291.8HV and flexural strength value of 42.4MPa have been achieved after pressing and sintering Co-HA composite at 1250°C. Observations were supporting the idea that Co-HA produced by modified electroless method was improving the mechanical properties with increasing the sintering temperature.

Abstract: Environment-friendly membranes were fabricated from poly (lactic acid) (PLA) via the electrospinning technique. PLA is selected due to its biodegradability and thermoplastic. Firstly, the electrospinning parameters that affect the membrane structure and fibers morphology were identified. These include the polymer solution concentration, flow rate and salt additive. It was found that low concentration lead to smaller fiber size but with beads, and lower flow rates leading to thinner and uniform fibers, while salt additives limited the formation of beads. It was found that hot pressing only is preferred from the view of small pore size, large porosity and high contact angle.

Abstract: Neem (Azadirachta indica) leaf powder was modified using a chelating agent, ethylenediaminetetaraacetic dianhydride (EDTAD) and the adsorption performance in removing methylene blue (MB) was investigated under batch mode. The EDTAD modified neem leaf powder (ENLP) was characterized by spectroscopic technique and elemental analysis. Fourier transform infrared (FTIR) spectra indicated that the ROH, RCOOR, RCOO^- and RNH₂ groups were involved in the removal of MB. The maximum adsorption capacity calculated from the Langmuir isotherm model was 178.57 mg/g at 318 K. Adsorption kinetic was found to be fitted well with the pseudo-first-order model. This study suggests that ENLP can be an attractive adsorbent for MB removal from diluted industrial wastewater.

Abstract: Anodic oxidation is an electrochemical method for the production of a ceramic film on a metallic substrate. It involves the use of an electrical bias at relatively low currents while the substrate is immersed in a weak organic acid bath. The films produced are usually dense and stable, with variable microstructural features. In the present work, ceramic films of the anatase and rutile polymorphs of TiO₂ were formed on high-purity Ti foil (50 μm) using mixtures of β-glycerophosphate disodium salt pentahydrate (β-GP) and calcium acetate monohydrate (CA) solutions. The experiments were carried out at varying voltages (150-350 V), times (1-10 min), and current density (10 mA.cm^-2) at room temperature. The ceramic films were characterised using digital photography, glancing angle X-ray diffraction (GAXRD), and field emission scanning electron microscopy (FESEM). The thicknesses of the films on Ti were measured using focused ion beam (FIB) milling. The colour, microstructures, and thicknesses of the films were seen to be strongly dependent on the applied voltage. At bias <200 V, single-phase anatase was observed to form on Ti, while at higher bias (250 V), rutile formed due to the arcing process.