Biodiesel production by enzymatic process using Jatropha oil and waste soybean oil

In this study, non-edible Jatropha oil and postcooking waste soybean oil were utilized for enzymatic biodiesel production. The process was optimized by using a statistical method. In addition, a novel continuous process using co-immobilized Rhizopus oryzae and Candida rugosa lipases was developed. The optimum conditions for the batch process were determined to be a reaction temperature of 45oC, an agitation speed of 250 rpm, 10 wt% of water, and 20% of immobilized lipases. A conversion of about 98% at 4 h could be achieved for biodiesel production using Jatropha oil, while a conversion of about 97% at 4 h was achieved from waste soybean oil. A packed bed reactor charged with co-immobilized lipases was employed for continuous biodiesel production from Jatropha and waste soybean oil. The reactor consisted of a jacketed glass column (ID 25 mm × 130 mm), in which a temperature of 45°C was maintained by water circulation. A maximum conversion of about 80% in 24 h at a flow rate of 0.8 mL/ min was achieved with the continuous process, whereas in the two-stage continuous process, a conversion of about 90% in 72 h was attained at a flow rate of 0.1 mL/min.