Valorization of waste seed oil from Cupressus macrocarpa L. for biodiesel production via green-synthesized iron oxide nanoparticles: A sustainable approach toward decarbonization
Rozina Rozina, Okezie Emmanuel, Mushtaq Ahmad, Ademola Duduyemi, Muḥammad Musḥtaq Aḥmad, Amjad Khan, Rutherford Esiaba, Christopher Elekwachi
Abstract
The urgent need to combat climate change and reduce reliance on fossil fuels has accelerated the global transition toward renewable energy. Consequently, waste-to-biofuel conversion offers a promising pathway to both sustainable energy production and circular resource use. This study investigates the potential of a novel feedstock , Cupressus macrocarpa L., with a high nonedible seed oil content of 26% (w/w), for biodiesel production. Iron oxide nanoparticles (Fe 2 O 3 NPs), synthesized using an aqueous leaf extract of Salvia moocroftiana L., were employed as a cost-effective and recyclable catalyst for the transesterification process. Under optimal conditions—methanol to oil molar ratio of 9:1, catalyst loading of 0.7 wt%, temperature of 60 °C, and a reaction time of 120 min—the process achieved a 93% conversion to fatty acid methyl esters (FAME). The Fe 2 O 3 NPs catalyst, with an average particle size of 30 nm, effectively catalyzed the reaction and demonstrated reusability over 5 cycles. Analytical techniques, including Fourier transform infrared spectroscopy and nuclear magnetic resonance , confirmed FAME production, while gas chromatography-mass spectrometric analysis identified 9-octadecenoic acid methyl ester as the primary biodiesel component. The final product met international fuel standards and achieved an ultra-low sulfur concentration of 0.0009%, highlighting its environmental and economic viability.