Enzymatic production of biodiesel from Pistacia chinensis bge seed oil using immobilized lipase

Biodiesel fuel from renewable non-edible woody plant oils has recently attracted more attention due to its environmental benefits and the reduced costs of raw materials. This study investigated the enzymatic transesterification of Pistacia chinensis bge seed oil (PCO) with methanol. The recombinant Rhizopus oryzae lipases (ROL) immobilized on macroporous resin and anion exchange resin, named as MI-ROL and AI-ROL, respectively, were used as biocatalysts. The transesterification reaction catalyzed by the immobilized lipase was investigated in a solvent-free system. The highest biodiesel yields of 92% and 94% were achieved under the optimum conditions (enzyme dosage 25 IUAI-ROL/g PCO or 7 IUMI-ROL/g PCO, methanol to oil molar ratio 5:1, water content 20% by weight of oil, temperature 37 °C, and reaction time 60 h). There was no obvious loss in the yield of biodiesel after being consecutively used for five cycles in the transesterification reactions using AI-ROL, while the yield of biodiesel remained above 60% after the MI-ROL was repeatedly used for four cycles.