Optimization of Simultaneous Esterification and Transesterification of Waste Cooking Oil using Biomass-based Bifunctional Catalyst via Taguchi L9 Approach.

Abstract

The utilization of biomass-based heterogeneous catalysts in biodiesel production is an ecofriendly and sustainable method. This investigation focuses on assessing the catalytic activity of a biomass-derived catalyst, synthesized from eggshells and orange peel waste. Characterization using techniques such as scanning electron microscopy (SEM), thermogravimetric analysis (TGA), energy dispersive X-ray fluorescence (EDXRF), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and Brunauer–Emmett–Teller/Barret–Joyner-Halenda (BET/BJH) revealed a substantial surface area of 134.562 m 2 /g for the prepared catalyst. The Taguchi methodology facilitated the experimental design, optimizing and modeling of simultaneous esterification and transesterification of waste cooking oil (WCO). Monitoring included waste oil biodiesel (WOB) yield and acid value (AV). Methanol-to-oil molar ratio and time significantly influenced WOB yield, while catalyst loading and temperature notably affected WOB AV. Under optimized conditions (methanol-to-oil ratio 12:1, catalyst loading 1 wt.%, temperature 55°C, reaction time 120 min), a maximum WOB yield of 95.27 wt.% and AV of 0.452 (mg KOH)/g were achieved. The WOB's physicochemical characteristics met the biodiesel standards of ASTM D6751 and EN 14214. Additionally, the catalyst, derived from eggshells and orange peel waste, demonstrated efficacy in both esterification and transesterification of WCO, with the ability to be reused for at least four cycles, yielding substantial WOB.