Pseudomonas cepacia lipase immobilized onto chitosan-coated polystyrene beads for biodiesel production

Abstract

In this research, chitosan-styrene copolymer coated onto polystyrene beads (CHI-STY/PS beads) was used as the solid support and the lipase of Pseudomonas cepacia (P. cepacia) was immobilized onto CHI-STY/PS beads by using glutaraldehyde as linker (GLU-CHI-STY/PS beads). Immobilization of lipase onto GLU-CHI-STY/PS beads was used as a catalyst for biodiesel production through transesterification reaction of soybean oil. For transesterification reaction, P. cepacia (30 mg) immobilized onto 15%GLU-2%CHI-15%STY/PS beads (1 g) at 30oC for 72 hours was used as a catalyst for biodiesel production. The lipase activity, protein loading yield and specific activity of this catalyst gave the optimal value at 54.43 U/g-support, 72.93% and 2.49 U/mg-protein, respectively. The effects of molar ratio of oil to alcohol, amount of catalyst, temperature and reaction time in the transesterification reaction were investigated. The optimum conditions were 1:5 oil/ethanol molar ratio (three step addition of anhydrous ethanol), 0.4294 g catalyst at 40°C for 32 hours. The highest ethyl esters yield was 91%. The ethyl esters production retained 87% of the original conversion after being reused for 5 batches.