Enzymatic Production of Biodiesel from Waste Sunflower Oil using Rubber-Fe3O4@SiO2@Lipase as Heterogeneous Nano-Biocatalyst: Optimization by Response Surface Methodology

This work aims at developing a protocol for green and clean biodiesel production from waste sunflower oil by the Rubber-Fe3O4@SiO2@Lipase nano-biocatalyst. Billions of tons of used tires were produced annually and billions of liters of waste cooking oil also were produced. Both of them cause environmental problems and finding ways to return them to usage cycle is very important from circular economy point of view. The Fourier transform infrared (FTIR) spectra successfully confirmed the lipase immobilization on the nanoparticles. The immobilized lipase has superior properties like higher thermal stability, higher relative activity at high temperatures, broader pH range for use, and easy recovery. The potential of immobilized enzyme was investigated for biodiesel synthesis and its catalytic efficiency was evaluated. The results were optimized by response surface methodology (RSM) as follows: 20.23 h, 5.2 wt. %, 21.58 mgL-1, 2.11 wt.%, 50°C and 5.30:1 was found for reaction time, catalyst dosage, Tween 80 concentration, water, reaction temperature and the molar ratio of alcohol to oil, respectively. The results showed that the synthesized immobilized lipase led to a fatty acid methyl ester of 94.89% conversion under optimized conditions. The modified lipase was reused five times in the reaction and the FAME conversion was higher than 80%.