Lipase-coated K2SO4 micro-crystals: Preparation, characterization, and application in biodiesel production using various oil feedstocks

This study investigated the preparation and characteristics of protein-coated microcrystals (PCMCs) from Pseudomonas cepacia lipase (PS) and K2SO4, and their application in biodiesel synthesis, via single factorial experiments and response surface methodology (RSM), the optimized PCMC-PS exhibited high activity and stability; the optimal temperature was 60 °C (which gave 99.83% conversion), although fairly high activity was exhibited after incubation at different temperatures (25–70 °C). The organic solvents stability of the PCMC-PS was improved, and it significantly reduced ethanol toxicity. Circular dichroism (CD) analysis revealed the correlation between the conformation and the enzyme activity. The morphology of the PCMC-PS was also confirmed via scanning electron microscopy (SEM). When catalyzed by PCMC-PS, above 83% biodiesel yield was obtained for most of the seven oils tested. The PCMC-PS (washed with hexane) activity remained relatively stable after eight batch reactions, with only a 15.73% reduction in the conversion (from 99.02% to 83.29%).