Co-catalysis of modified metal-organic framework immobilized enzyme with nonionic surfactant for biodiesel preparation.

With the increasing demand for sustainable energy, enzyme-catalyzed biodiesel preparation has garnered significant interest owing to its green and efficient characteristics. However, conventional immobilized lipase (LIP) is susceptible to desorption and inactivation and fails to balance the catalytic efficiency and stability, limitations that seriously restrict the industrial application. To address this, we constructed a carrier through hydrophobically modifying University of Oslo-66-NH2 (UiO-66-NH2), an amino-functionalized metal-organic framework (MOF), with octadecylphosphonic acid (OPA). Subsequently, OPA/UiO-66-NH2 was employed to immobilize LIP. Under optimal conditions, the immobilization capacity of OPA/UiO-66-NH2@LIP reached 48.59 mg/g. Compared to free LIP, OPA/UiO-66-NH2@LIP exhibited superior thermostability, pH adaptability, and storage stability, retaining 85.0 % activity after 30 days. Using sunflower oil as the substrate, a biodiesel conversion of 84.8 % was achieved under optimized parameters. After adding 2 % fatty acid methyl ester ethoxylate (FMEE), interfacial activation enhanced the catalytic efficiency, increasing the conversion to 99.2 %, moreover, this value remained at 84.1 % after ten cycles. This study combines carrier engineering with interfacial activation to develop a novel nano-immobilized biocatalyst with promising potential for biodiesel synthesis.