Enzymatic transesterification of Calophyllum inophyllum oil by lipase immobilized on functionalized SBA-15 synthesized from low-cost precursor

Enzymatic transesterification of crude non-edible Calophyllum inophyllum oil with high level of free fatty acid (FFA) was investigated. As acid/alkali transesterification for biodiesel production requires expensive pre-treatment and is energy consuming, enzymatic conversion using immobilized lipase is preferred for oils with high FFA. In the present work, sugarcane leaf ash is used for synthesis of SBA-15. The SBA-15 was subsequently functionalized with carboxyl, amino, thiol, and phenyl groups for the lipase immobilization. Amine-functionalized mesoporous silica showed maximum percentage immobilization (49 %) and specific enzyme activity (9.858 U/mg) for immobilized lipase. Under optimal conditions for processing 2 g of Calophyllum inophyllum oil: lipase immobilized on amine-functionalized SBA-15—125 mg, methanol/oil molar ratio—6:1, water—15 % v/v and temperature—35 °C the percentage yield of methyl ester was 94 %. The reusability study had shown long-term stability of lipase activity for methanolysis.