Key Engineering Materials Vols. 594-595

Abstract: Membrane has been used widely in developed countries and most of researchers focus on the development of membrane formulation. However, different materials with different portion give a various effects on the membrane morphology and performances. Hence, blend polymer is one of the method that can be explored to produce the best membrane performance. This present study aims to identify an ideal formulation of blend polymers in membrane fabrication process. Dope solution was prepared using these materials; cellulose acetate (CA) and polysulfone (PSf) are blended together as polymer, N,N-Dimethylacetamide (DMAc) as solvent and Polyvinylpyrrolidone as an additive in membrane fabrication. Best formula for blended polymer was tested on the performance test; salt rejection, flux of salt and Field Emission Scanning Electron Microscopic (FESEM).

Abstract: This work aims to develop an extraction process for valuable chemicals such as phenolic bio-oil derived from pyrolysis techniques consists of a complex mixture of phenolic, organic acids, ketones and aldehydes compounds. Chemicals such as phenolic compound and acetic acid are attractive for extraction due to their high value compared to fuel and energy product. In this study, synthetic bio-oil is synthesized to represent the actual pyrolysis oil and selection of suitable salt concentrations has been investigated for systematic extraction system development. Synthetic bio-oil was characterized and the results found to be comparable with the properties of pyrolysis oil. Optimum ammonium sulfate concentration for extraction were in the range of less than 20 wt.%. The highest acetic acid yields was 0.1948 wt.% at 20 wt.% concentration of (NH₄)₂SO₄. While, phenol was rich in organic phase with the highest yield at 30 wt.% of (NH₄)₂SO₄.

Abstract: Biopolymer foam was prepared based on vegetable oil and Polyol Flexible (Epoxy) with commercial Polymethane Polyphenyl Isocyanate (Modified Polymeric-MDI) as laminated foam. The acoustic property of biopolymer foam was examined by impedance tube test according to ASTM E-1050 of sound absorption coefficient (α). From the result obtain, sample D and sample C are the best result of sound absorption coefficient (α) for biopolymer foam and epoxy foam with the value are 0.867 and 0.817 respectively. By using the sound behavior theory, when the thickness is increase the sound absorption is also increase as same as in this study. The noise reduction coefficient (NRC) of sample D is 38.26% while for sample C is 37.42%.

Abstract: Urea is extensively used as fertilizer in the agricultural industry based on its suitability for all types of crops. The hydrolysis of urea fertilizer produces ammonia (NH₃) and carbon dioxide (CO₂). However, up to 40% of NH₃ release affects the efficiency of urea fertilizer. By introducing inhibitors into the urea enzymatic reaction, the NH₃ emission problem can be solved. Unfortunately, current inhibitors are usually chemical based and non-biodegradable. Several complaints and accidents have been reported when handling chemical based inhibitors especially for surface application. Research on garlic or Allium savatium has been conducted to ensure its inhibitory effects as potentially safe and biodegradable inhibitor. From previous research, thiosulfinates (TS) contained in garlic extract proved to inhibit platelets aggregation in medical applications. In this study, the inhibitory effect is determined by analyzing NH₃ concentration in urease-garlic mixture and standard urea assay mixtures using UV-VIS spectrophotometer device. Previous research showed the highest absorbance of free NH₃ was detected at 370nm. At 30 minutes of 15ml of urease-garlic mixture confirms the fully inhibition of garlic extract towards reaction.

Abstract: Phoenix dactylifera L. type Mariami from Iran was chosen for this study to investigate the solubility of its seed oil in supercritical carbon dioxide (SC-CO₂). The seed has been discovered to possess an antioxidant. The extraction method using SC-CO₂ solvent was used in this study to investigate the capabilities of supercritical fluid to extract Phoenix dactylifera L. seed oil since the method is clean compared with organic solvent extraction. Solubility of Phoenix dactilyfera seeds oil in SC-CO₂ was correlated using empirical density based model with the help of IBM SPSS software for significance and correlation analysis of the models. Analysis of component in the oil was done using gas chromatography equipped with mass spectrometry (GC-MS). Oleic acid revealed to be the main fatty acid in Phoenix dactylifera seed oil, followed by palmitic acid, lauric acid, ascorbyl palmitate and others.

Abstract: Ni deposited on HA powder was prepared by electroless plating process without sensitization and activation treatment. The deposited powder obtained was characterized by energy dispersive spectroscopy (EDX) and x-ray diffraction (XRD). The microstructure and hardness of the sintered powder were examined by scanning electron microscopy (SEM) and Vickers hardness respectively. From the result, the nickel existence in the deposition was confirmed by the EDX analysis. The diffraction peaks at 44.5 and 64.7^o (2θ) of planes (111) and (211) respectively were belong to nickel. Nickel are homogeneously dispersed in HA matrix with grain size between 0.25-2μm after sintered at 1250°C. The improvement of 93% and 180% in average hardness and flexural strength respectively were achieved with nickel presence in HA compared to pure HA.

Abstract: HA-Ni composites were fabricated by uniaxial pressing from coated powders, in which HA particles were successfully coated with nickel precursor by the electroless deposition method. The compacted powders sintered at temperature 1200°C for 1h. Decomposition of hydroxyapatite into α-TCP (α tricalcium phosphate) and TTCP (tetracalcium phosphate) were not occured in any different nickel content before and after sintering. The Ni peaks sharply increased with increasing of Ni content indicate that high crystallinity of metal and confirmed the existence of nickel in the composites. Compared with that of pure HA, the fracture strength of HA inproved by almost 200% by adding 1wt% Ni due to the increase of the composites density. The enhancement in mechanical properties of HA-Ni composites was found to decrease with increase of Ni content, which attributed to the size effect of nickel grains and higher porosity percentage of composites.

Abstract: The study aimed to investigate the effect of initial glucose concentration on the microbial cellulose production using Acetobacter xylinum in a Rotary Discs Reactor (RDR-2 liter volume). The fermentations were carried out for four days at temperature 28°C, initial pH 6.5, and 9 rpm of rotation speed; meanwhile, the initial glucose concentration was manipulated in the range of 0.5-5.0 % (w/v). The cell growth was stimulated using 1.4% (v/v) ethanol in the fermentation medium. The result indicated that 1% (w/v) of initial glucose concentration provided the highest microbial cellulose yield with total wet weight of 296.1657g/l. The increase of initial glucose concentration resulted to the decrease of microbial cellulose yield and greater pH drop after fermentation. It can be conclude that production of microbial cellulose using RDR could produce relatively much higher microbial cellulose with less amounts of glucose in a shorter fermentation period compared to static fermentation due to more efficient oxygen uptake during rotary movements and homogenous environment for microbial growth.

Abstract: This paper presents a review on Malaysia and Thailand’s view on renewable energy mainly in the area of solar energy. It is based on a survey conducted on random subjects in Malaysia raging from different discipline such as those from RE and non RE industries, and several learning Institution. The survey was conducted on random subject as to create a variance on their given answers. A total of 6,450 Malaysian have answered the survey which is then analyzed and compared with the views and current RE scenario in Thailand. The data analysis for Thailand is obtained from literature review. Based on the analysis, one could conclude that both Malaysia and Thailand are on the same objective which is to expand and cultivate their RE sources and has adapt an alternative method to sustain their energy development.

Abstract: Agricultural wastes such as palm ash and rice husk have a possibility to be used as a usefully renewable source for production of energy and silica (SiO₂). Extensive researches have been carried out to extract silica from agricultural wastes such as rice husk, due to silica as a useful raw material for industrial application. In the previous studies, the strong acid leaching treatment was carried out to remove metallic impurities and organics contained in rice husk. A strong acid leaching treatment, however, is significantly hazardous to the environment and people [. In this study, the environmentally benign and economically effective process to produce SiO₂ materials from palm ash has been established by using citric acid leaching, not the conventional strong acids. Results showed that silica can be extracted from palm ash using citric acid leaching treatment under the optimum extracting conditions with 70°C of solution temperature, 60 minutes of reaction time and concentration of citric acid of more than 2%. The purity of silica extracted is more than 90%.