| Summary: | The production of biodiesel from fish oil was carried out using enzymatic transesterification. The effects of the oil: alcohol molar ratio (1:1, 1:2, 1:3, 1:4 and 1:5), alcohol type (methanol and 2-butanol), reaction temperature (35, 40, 45 and 50ºC), reaction time (4, 8, 12 and 16 h) and solvent type (solvent and solvent-free) on the biodiesel conversion yield using Candida antarctica (Novozyme 435) and experimental enzyme (NS88001) were investigated. The biodiesel conversion yield increased when the reaction temperature was increased from 35 to 40ºC and then decreased when the reaction temperature was further increased to 45 and 50ºC, respectively. Increasing the oil: alcohol molar ratio from 1:1 to 1:4 increased the biodiesel conversion yield which then decreased when the oil: alcohol molar ratio was further increased to 1:5. The highest biodiesel conversion yield was obtained after 16 h at the oil: alcohol molar ratio of 1:4 and the reaction temperature of 40ºC using Novozyme 435 and NS88001 individually and in combination. No reaction was observed at the oil: alcohol molar ratio of 1:1 for Novozyme 435 enzyme and at 1:1 and 1:2 oil: alcohol molar ratios for NS88001 enzyme in a solvent- free system. The highest biodiesel conversion yield from Novozyme 435 (80.24%) was observed with 2-butanol, the highest biodiesel conversion yield from NS88001 (74.34%) was observed with methanol and the highest biodiesel conversion yield from the combination of enzymes (Novozyme 435 and NS88001) lipase (82.37%) was observed with 2-butanol. The stability of the enzymes Novozyme 435 and NS88001 individually and in combination slightly decreased after 10 cycles and completely stopped after 20-30 cycles.
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