Preparation of biodiesel catalyzed by immobilized lipase in magnetic ZIF-8 nanomaterial

The main objective of this study was to produce biodiesel utilizing Fe₃O₄@ZIF-8-CRL as biocatalyst, employing high acid value waste oil. Candida Rugosa lipase (CRL) was immobilized onto a magnetic ZIF-8 organometallic framework through physical adsorption, resulting in significantly enhanced stability and chemical compatibility. The study extensively investigated the impacts of enzyme dosage, alcohol-to-oil ratio, ultrasonic power, temperature, time, and the addition of deep eutectic solvents on the conversion of fatty acid ethyl esters. The findings revealed that under the conditions of biocatalyst addition of 5.7 wt.%, alcohol–oil ratio of 6:1 mmol/g, ultrasonic power of 87.297 W, reaction temperature of 40 °C, and reaction time of 2 h, the innovative biocatalyst facilitated a conversion efficiency of fatty acid ethyl esters reaching 82.06 ± 1.63%, with a retention rate of 74.52% after three cycles. Additionally, characterization of the biocatalyst using a vibrating sample magnetometer and scanning electron microscopy demonstrated its favorable magnetic recovery potential and morphology. Coupled with its straightforward and efficient synthesis, this biocatalyst proves to be competitive in the catalysis of biodiesel preparation.