Lipase Immobilized into Novel GPTMS: TMOS Derived Sol-Gels and its Application for Biodiesel Production from Waste Oil

In this essay, lipase from Burkholderia cepacia was immobilized into 3-glycidoxypropyltrimethoxysilane (GPTMS) and tetramethoxysilane (TMOS) derived sol-gels. GPTMS:TMOS molar ratio of 1:3 was found to yield the best result. The morphological characteristics were investigated based on SEM and BET analysis. Sample mean pore diameter was 39.1 nm, it had a specific surface area of 60 m2/g prior to enzyme addition which decreased to 7.49 m2/g after immobilization. The enzyme activity was assessed through transesterification of waste cooking oil in the presence of ethanol with optimal conditions of: 40ᵒC, 15% immobilized lipase, 9:1 alcohol to oil molar ratio in 24 h of reaction which resulted in 91.70% biodiesel production. In 6-hour reaction time, 86.87% biodiesel was obtained which is much shorter than conventional enzymatic transesterification which is 72 h. Ethyl esters were characterized by determining their viscosity, density, and flash point based on ASTM D 6751-07b standards.