Evaluation of hybrid catalyst with lipase immobilized on potassium oxide-carbon beads for biodiesel production

Immobilized lipase, known for its specificity and ability to minimize undesired byproducts, has gained considerable attention as biocatalyst in the renewable energy field. In this study, Candida rugosa lipase (CRL) was immobilized on K2O-C/γ-Al2O3 forming CRL@K2O-C/γ-Al2O3 hybrid catalyst using efficient method. Catalyst dual composition, which integrates enzymatic and chemical active sites within a single catalytic system, demonstrated synergistic effects in biodiesel production by enabling reactants to interact with both lipase and inorganic catalytic sites, thereby providing favourable hybrid reaction conditions. The successful immobilization of lipase was confirmed through physicochemical analyses of catalyst which showed a 71.24 % activity recovery. Statistical optimization of catalyst synthesis variables using response surface methodology (RSM) approach, resulted in 69.06 % biodiesel yield from waste cooking oil (WCO) under synthesis conditions of 2.04 mg/mL CRL concentration, immobilized for 4.5 h at 20 °C, and agitation speed of 145 rpm. In addition, biodiesel produced under optimized reaction conditions met ASTM D6751 and EN 14214 standards. Furthermore, the process followed pseudo-first-order kinetics with activation energy of 18.81 kJ mol−1. Overall, these findings highlight the potential of CRL@K2O-C/γ-Al2O3 hybrid catalyst for efficient biodiesel production, driving yield improvements from WCO and contributing to sustainability in the renewable energy sector.