Tosylated cloisite as a new heterofunctional carrier for covalent immobilization of lipase and its utilization for production of biodiesel from waste frying oil

Abstract

In this paper, cloisite 30B (CL) was converted to tosylated cloisite (TCL) as new heterofunctional support. Lipase from Candida rugosa was covalently immobilized on the TCL (TCLL) and used to produce biodiesel from waste frying oil (WFO). The effects of reaction time and temperature, the molar ratio of methanol/oil, and the water content on the biodiesel yield were also explored. The hydrolytic activity of TCLL was 1.96 ± 0.04 U mg−1, with the immobilization yield of 93.6% and expressed activity of 90.2%. The maximum yield of biodiesel (97.1 ± 1.1%) was obtained at 50 °C for 8 h with a 15:1 M ratio of methanol to WFO and water content 10 wt%. The features of produced biodiesel, such as acid value, iodine value, density, and viscosity, met the specifications in the reported standard test methods. After 24 h incubation at 80 °C, the relative yield of biodiesel for TCLL was 20.3%, while the relative yield for the free enzyme was almost zero. The relative yield of biodiesel for TCLL and free lipase was 70.6% and 33.4%, respectively, after 30 days of storage. Also, TCLL showed a relative yield of 61.3% in the biodiesel production after being used for 10 cycles.