Vacuum-assisted adsorption of Candida rugosa lipase with nanotubes for monooleoglycerol synthesis

Abstract

A surplus of crude glycerol has been produced as a by-product due to the escalating production of biofuels. Utilization of crude glycerol for monoolein production which offers a different approach using the abandoned crude glycerol from the biodiesel sector is the main aim of this study. Immobilized lipase was used in this investigation to catalyse the direct esterification of oleic acid and glycerol, which resulted in monoolein. The immobilized Candida rugosa lipase onto the halloysite nanotubes (HNTs) has shown remarkably promising attainment of lipase activity and loading capacity. The immobilised lipase was optimised for crucial parameters (HNT to lipase ratio, pH, temperature, and pressure) via response surface methodology (RSM). The recommended optimum conditions obtained are pH 6, 38.6 °C, and 0.33 atm (81.92% lipase activity). To analyse influences of reaction period, temperature, mixing rate, and crude glycerol to oleic acid molar ratio on the esterification reaction was carried out using the optimized conditions of immobilization process. The optimum conditions for physically immobilised lipase were to yield 88.97% monoolein produced at 42 °C in a substrate ratio of 1:4 (oleic acid: glycerol) stirred at 200 rotations per minute (rpm) with 16 h’ incubation time. Based on the research's findings, it was confirmed that HNT has good application potential for enzyme immobilization carriers.