Neem oil was extracted from neem seeds by mechanical extraction method. Yield of oil was 21.32%. The physicochemical properties of the extracted oil were studied in detail. The oil corresponds to diesel except acid value (14.21%) and sulphur content. Acid esterification was performed to reduce the acid value which was followed by transesterification to produce biodiesel. The conditions of the transesterification of the oil were optimized and were found to be 20% methanol and 1.0% NaOH at 60 ̊ C for 90 min. The optimum yield of biodiesel was 98 %. Finally, the performance study in a diesel engine was conducted with diesel and biodiesel blends. The brake thermal efficiency for 5% blend of biodiesel was 16.67% for brake power of 0.79 KW.Bangladesh J. Sci. Ind. Res.53(3), 211-218, 2018

The Pithraj seed has been collected from Gazipur district, Bangladesh. The oil from the seed was extracted by using Soxhlet apparatus using petroleum ether extraction method. Maximum yield of oil was found to be 50 % when the process was carried out for 2.5 hours. The physicochemical properties of the extracted oil were studied. The properties of the oil reveal that the oil corresponds to diesel except acid value and sulphur content. The optimum conditions of the transesterification of the oil was 40% ethanol and 0.45% KOH at 75 0 C for 1.5 hours. The optimum yield was more than 95 %.

Biogas, produced from organic waste through anaerobic digestion (AD), is mainly composed of methane (CH4) and carbon dioxide (CO2) with smaller amount of hydrogen sulfide (H2S) and nitrogen (N2). Trace amount of some other gases are occasionally present in biogas. For electricity generation from biogas, reduction of H2S is necessary because it is toxic and corrosive to most of the equipments. Reduction of Hydrogen Sulfide (H2S) from poultry based biogas (normally it contents 1500~2500 ppm) can be done by dosing air/oxygen to the main digester during the digestion process. Two methods of air injection technique have been followed for optimization of the process. Firstly two hour interval air injection and secondly air injection based on percentage of hourly gas production. The optimum air percentage to minimize H2S should be at least 3.00%. After aeration H2S level comes to the desired level (<50ppm) within 1.5-2.0 hours and remains constant up to 7-9 hours and biogas can be used for effective power generation. A complete aeration system has been developed which is simple and cost effective for H2S reduction to the desired level from poultry based biogas plant. This system can be applied for any size of poultry based biogas plant for effective power generation. Key words: Anaerobic digestion; Hydrogen Sulfide (H2S); Aeration; Biogas digester; Power generation DOI: http://dx.doi.org/10.3329/bjsir.v46i3.9040 BJSIR 2011; 46(3): 339-342

Production and characterization of bio lubricating base oil from non-edible castor seed oil has been studied. Castor oil was extracted from castor seed by solvent extraction method. KOH catalyzed transesterification process was used to produce bio-lubricating oil. Ethanol was used as alcohol in the transesterification process. Optimum condition for bio-lubricating base oil production was 40% ethanol, 0.45% KOH at 75oC for reaction time of 90 min. and the yield was 98%. Important properties of produced bio-lubricating oil like acid value (0.58 mg KOH/g), flash point (235oC), density (0.890 g/cc), pour point (-15oC) and viscosity (131.90 and 16.5 cSt at 40 and 100 oC respectively) etc. were analyzed. The properties were found to be analogues to conventional commercial lubricating oil. This renewable base oil from castor seed could be an attractive and environment friendly alternative to base oil from petroleum sources. Bangladesh J. Sci. Ind. Res. 57(1), 7-14, 2022

Enzymatic saccharification (Hydrolysis) is one of the technologies to hydrolyze lignocellulosic biomass. In this study, Bangladeshi bagasse is used as feedstock for enzymatic saccharification and ethanol fermentation. Cutter mill and Mechano-chemical treatment (Ball mill) are used for pretreatment. The main objective of this study is to investigate the effect of substrate concentration, pretreatment time and enzyme concentration to enzymatic hydrolysis and ethanol fermentation. The yield of glucose from cellulose is decreased with increasing substrate concentration from 5% to 15%, but the total amount of glucose is increased with increasing substrate concentration. Sample with long pretreatment time hydrolysis easily. Ball milling pretreatment of 1 hour is the most effective on enzymatic hydrolysis which gives better sugar yield than others. Enzyme loading has significant effect on enzymatic hydrolysis. Yeast Saccharomyces cerevisiae was used to converts C 6 sugar into ethanol and incubated at 30 o C for 96 hours. Almost all fermentable sugar converted into ethanol within 24 hours.