Synthesis, Characterization and Optimization of Alumina-Supported, Biogenic CaO Catalysts for Enhanced Biodiesel Production from Waste Peanut Oil.

Abstract

Biodiesel is a sustainable and commercially viable alternative to fossil fuels, offering a viable solution to the rising global energy and environmental challenges. This study examined the transesterification of waste peanut oil into biodiesel using a calcium oxide catalyst supported on alumina (CwChFh-A6). The catalyst was prepared by calcining animal bones derived from cow, chicken, and fish sources to improve basicity and thermal stability. The catalysts' elemental composition, thermal characteristics, and functional groups were ascertained by means of Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and energy-dispersive X-ray (EDX). Waste peanut oil was pre-treated to lower its iodine, peroxide, saponification, and free fatty acid values, rendering it more suitable for the production of biodiesel. The synthesized CwChFh-A6 produced a high biodiesel yield of 97% under optima reaction conditions with a turnover frequency (TOF) of 0.339 min⁻¹, a turnover number (TON) of 4.64. The main fatty acid methyl ester (FAMEs) identified by GC-MS analysis were methyl oleate (C18:1), methyl stearate (C18:0), and methyl linoleate (C18:2), with an overall purity of more than 96%. The statistical modelling showed a good fit (R2 > 0.9311), and reaction temperature and time were found to be the primary factors influencing the obtained biodiesel yields. These findings exhibit the potential of waste valorization in enhancing quality production of biodiesel.