Immobilization of Lipase on Metal-Organic frameworks for biodiesel production

A comprehensive study on lipase immobilization on ZIF-67, ZIF-8, and HKUST-1 and their use in biodiesel production were performed. The highest adsorption capacity of 26.9 mg/g was achieved using ZIF-67 at 45 °C and an initial protein concentration of 0.6 mg/mL. Adsorption equilibrium data suggested that lipase adsorbed physically on ZIF-67 and ZIF-8 and chemically of HKUST-1. The data were best fitted with the Langmuir isotherm model for the three supports. Whereas, adsorption kinetics data were best fitted using Elovish's model for ZIF-67 and ZIF-8, and the pseudo-second-order model for HKUST-1. It was also found that the process was influenced by intraparticle and film diffusion. The prepared bio-catalyst was successfully used to catalyze biodiesel production in a co-solvent medium. The ZIF-8 and ZIF-67 showed better catalytic activity, achieving 88% and 90% conversion, whereas HKUST-1 showed better reusability due to the stronger chemical adoption. In addition, diffusion-reaction kinetics of biodiesel production using adsorbed lipase on ZIF-8 have been analysed. The investigation provided an insight into adsorption pathways and probable mechanisms involved and a better understanding of their application in biodiesel production. Mathematical diffusion-reaction modeling of lipase-MOFs biocatalyst used in biodiesel production, similar to the one presented in this work, is not found in literature.