Facile synthesis of Fe3O4@biochar@SO3H as magnetically separable Bronsted acid nanocatalyst for biodiesel production from different oil feedstocks

Abstract

A novel magnetically separable Fe3O4@biochar@SO3H catalyst was developed from mesua assamica (King & prain) waste seed shells biochar for cost-effective biodiesel production using novel mesua assamica seed oil, jatropha oil, and soybean oil. The magnetic solid acid catalyst was synthesized via impregnation of biochar with Fe3O4 magnetic nanoparticles followed by sulfonation techniques. Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) analysis suggested the successful sulfonation and existence of –SO3H groups on catalyst surface. The synthesized magnetic acidic catalyst possesses total acidity of 3.9 mmol g−1 and –SO3H density of 1.8 mmol g−1. The field emission transmission electron microscopy (FETEM) led core-shell structured catalyst particle demonstrated a mean size of 87.4 nm and the surface area of 71.47 m2 g−1. The acidic catalyst easily afforded maximum yield of 96.8% mesua assamica biodiesel, 95.3% jatropha biodiesel, and 95.8% soybean biodiesel under optimized reaction parameters. The kinetic investigation suggested the occurrence of pseudo first order kinetics with activation energy of 32.42 kJ mol−1. The magnetically separable catalyst also displayed promising activity and stability up to 3rd cycle with more than 75% biodiesel yield.