A sustainable and renewable biobased polyester polyol for polyurethane production was synthesized through the esterification of azelaic acid and sorbitol catalyzed by tin­(II) oxide in a batch system. The studies on chemical equilibrium, reaction kinetics and important operating parameters were carried out. The temperature, molar ratio of sorbitol to azelaic acid and catalyst loading were varied in order to determine the best reaction conditions. The polyester polyol synthesized was tested for its fatty acid content through titration. The best operating condition found was at reaction temperature of 433 K, sorbitol to azelaic acid molar ratio of 4:1 and catalyst loading of 2 wt %, yielding 72% azelaic acid conversion after 6 h of reaction. The presence of minute amount of sorbitan and isosorbide inferred the potential of sorbitol-based branched polyester formation with its backbone incorporated with these sorbitol anhydrides. The equilibrium study validated the endothermicity of the reaction. Meanwhile, the kinetic data well fitted to the Langmuir–Hinshelwood Hougen Watson (LHHW) model with the activation energy of 14.43 kJ/mol.

Indonesia is the world’s second largest producer of coconut. This at the same time resulted in huge generation of coconut shell waste that need to be properly managed to prevent environmental contamination such as water, air and soil pollution. Current techniques of physical and thermal processing are time and energy consuming. This study reports on the conversion of coconut shell biomass into biochar using microwave-assisted pyrolysis (MAP). The MAP processes were carried out at different microwave power (550-650W) and   residence time (15-25 minutes). Two of the highest biochar yields were obtained at 550W with the residence times of 15 minutes (91.31 wt%, termed as S1) and 20 minutes (83.88 wt%, termed as S2), respectively. Both values were higher than biochar yield obtained using conventional pyrolysis process i.e. 30.10 wt%. Both S1 and S2 showed considerable capacity to remove 0.6875 mg.g-1 and 0.5165 mg.g-1 methylene blue which had the initial concentration of 25 mg.L-1. The adsorption efficiencies of S1 and S2 biochars were 55.00% and 41.32%, respectively. Results obtained from the FTIR, FESEM and BET analysis also supported the methylene blue removal properties of both S1 and S2, respectively. As a conclusion, coconut shell showed potential as a useful raw material to produce biochar that can be used for methylene blue removal from solution. Nevertheless, more investigation need to be carried out prior to commercialization venture of the coconut-shell based biochar.

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Nyamplung seed (Calophyllum inophyllum L.) oil is a prospective non-edible vegetable oil as biodiesel feedstock. However, it cannot be directly used in the alkaline catalysed transesterification reaction since it contains high free fatty acid (FFA) of 19.17%. The FFA content above 2% will cause saponification reaction, reducing the biodiesel yield. In this work, FFA removal was performed using sulfuric acid catalysed esterification to meet the maximum FFA amount of 2%. Experimental work and response surface methodology (RSM) analysis were conducted. The reaction was conducted at the fixed molar ratio of nyamplung seed oil and methanol of 1:30 and the reaction times of 120 minutes. The catalyst concentration and the reaction temperature were varied. The highest reaction conversion was 78.18%, and the FFA concentration was decreased to 4.01% at the temperature of 60℃ and reaction time of 120 minutes. The polynomial model analysis on RSM demonstrated that the quadratic model was the most suitable FFA conversion optimisation. The RSM analysis exhibited the optimum FFA conversion of 78.27% and the FFA content of 4%, attained at the reaction temperature, catalyst concentration, and reaction time of 59.09℃, 1.98% g/g nyamplung seed oil, and 119.95 minutes, respectively. Extrapolation using RSM predicted that the targeted FFA content of 2% could be obtained at the temperature, catalyst concentration, and reaction time of 58.97℃, 3%, and 194.9 minutes, respectively, with a fixed molar ratio of oil to methanol of 1:30. The results disclosed that RSM is an appropriate statistical method for optimising the process variable in the esterification reaction to obtain the targeted value of FFA.

One of the microalgae that can be potentially used to produce bioethanol is Chlorella vulgaris, as it is rich in carbohydrates. However, the carbohydrates in C. vulgaris cannot be converted directly into ethanol. This study aimed to investigate the chemical and enzymatic hydrolysis of C. vulgaris, which is subsequently followed by fermentation. The catalysts used in the chemical hydrolysis were hydrochloric acid, sodium hydroxide, and potassium hydroxide, while the enzymes used were the mixture of alpha-amylase + glucoamylase, alpha-amylase + cellulase, and alpha-amylase + glucoamylase + cellulase. The hydrolysate obtained from chemical hydrolysis was fermented through Separate Hydrolysis Fermentation (SHF), while the one from enzymatic hydrolysis was fermented through Simultaneous Saccharification and Fermentation (SSF), in which both processes used S. cerevisiae. After undergoing five hours of enzymatic hydrolysis (using alpha-amylase + glucoamylase), the maximum glucose concentration obtained was 9.24 ± 0.240 g/L or yield of 81.39%.  At the same time and conditions of the substrate on chemical hydrolysis, glucose concentration was obtained up to 9.23 + 0.218 g/L with a yield of 73.39% using 1 M hydrochloric acid. These results indicate that chemical hydrolysis is less effective compared to enzymatic hydrolysis. Furthermore, after 48 hours of fermentation, the ethanol produced from SHF and SSF fermentation methods were 4.42 and 4.67 g/L, respectively, implying that producing bioethanol using the SSF is more effective than the SHF method.