Biogenic (Lantana camara L) synthesis of ZnO as a catalyst for the production of biodiesel from nonedible waste cooking oil: Materials characterization; studies of kinetics and thermodynamics of biodiesel production and optimization using RSM

Abstract

We report catalytic conversion of waste cooking oil (WCO) to biodiesel using nano-ZnO (photo catalyst) derived from Lantana camara L.. Characterization of catalyst using Energy Dispersive Spectrum (EDX) analysis shows strong signals of 1.5 keV and 0.7 keV for Zinc and Oxygen, respectively. Transmission Electron Microscopic (TEM) result shows uniform catalyst particle size distribution with crystallite d-spacing of 0.1054 nm. Catalyst BET surface area measurement found to be 41.5 m2 g−1 and the thermal stability of the material was evaluated using Kissinger-Akahira-Sonuse (KAS) model. The catalyst used for conversion of WCO shows high biodiesel yield (86 %) under the optimized reaction conditions i.e., methanol/oil molar ratio (10.5:1), catalyst loading (2.25 wt%), 65 °C and reaction time of 115 min which is in well agreement with calculated optimized response surface methodology (RSM). The produced biodiesel was analyzed using FTIR, 1H NMR and TGA/DSC. The WCO to biodiesel conversion follows pseudo-first-order kinetics (R2 = 0.9954). The kinetics of decomposition of biodiesel was evaluated using the non-isothermal Kissinger model-free method. The catalyst was tested up to six consecutive cycles without significance loss of percentage of yield.