Effect of silica coating on Fe3O4 magnetic nanoparticles for lipase immobilization and their application for biodiesel production

The scope of this study was to prepare different organosilane-modified Fe3O4@SiO2 core magnetic nanocomposites with immobilized lipase and explore their potential application in biodiesel field. Fe3O4 magnetic nanoparticles prepared by co-precipitation method were coated with various ratios of SiO2 as per Stöber method and further functionalized by different organosilane compounds APTES (3-aminopropyltriethoxysilane) and MPTMS (3-mercaptopropyltrimethoxysilane). Functionalized Fe3O4@SiO2 magnetic nanoparticles were immobilized with free lipase NS81006 by glutaraldehyde cross-linking reagent. The functional groups, structure, morphology and magnetic susceptibility of synthesized and modified Fe3O4@SiO2 magnetic nanoparticles were characterized by FTIR, XRD, SEM, TEM, and VSM techniques. The immobilization efficiency and activity recovery were reduced by increasing the ratio of silica coating on Fe3O4. Maximum activity recovery (84% by APTES, 83% by MPTMS) and biodiesel yield (>90%) were obtained by lipase immobilized on Fe3O4@SiO2 support when the Fe3O4 and SiO2 (TEOS) ratio was low (1:0.25).