Nanocatalytic conversion of Calotropis procera seed oil and latex into sustainable biodiesel using nickel oxide nanoparticles

Abstract

The present study explores the sustainable production of biodiesel from Calotropis procera seed oil using nickel oxide (NiO) nanoparticles as an efficient green nanocatalyst. The NiO nanoparticles were synthesized via an ecofriendly route employing Calotropis procera latex and were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses, confirming their nanoscale size range of 1.2–5 nm. Critical reaction parameters influencing biodiesel yield were systematically optimized. A maximum yield of 97.6% was achieved under optimal conditions: catalyst loading of 1.5 wt%, oil-to-methanol molar ratio of 1:9, reaction temperature of 65 °C, and a reaction time of 90 min. Fourier transform infrared (FT-IR) analysis confirmed the successful transesterification of seed oil into biodiesel through characteristic functional group transformations. Gas chromatography–mass spectroscopy (GC–MS) analysis revealed the presence of major fatty acid methyl esters (FAMEs), including methyl palmitate, methyl oleate, methyl arachidate, and methyl linoleate, contributing to the fuel quality. The catalyst reusability study demonstrated appreciable stability, retaining 74% efficiency after five cycles and 50% after seven cycles. The synthesized biodiesel exhibited physicochemical properties in compliance with ASTM standards, highlighting its potential as a viable, eco-friendly alternative fuel.