Spent Coffee Grounds (SCG) waste valorization: waste to wealth fuel feedstock

The increasing global energy demand requires a critical examination of our dependence on fossil fuels, prompting the exploration of sustainable and renewable energy alternatives. This study examines the transformation of spent coffee grounds (SCG) oil into biodiesel, presenting a cost-effective and environmentally friendly alternative by utilising sulfonated oil palm empty fruit bunch ash (EFBA) as a solid acid catalyst. The catalyst was characterised using Thermogravimetric Analysis (TGA) and Fourier Transform Infrared Spectrometer (FTIR). The SCG oil demonstrating its potential for biodiesel synthesis by transesterification. The ideal reaction conditions were established as a 7h reaction time with a catalyst loading of 30 wt.%. Under these conditions, the FFA value in coffee oil decreased significantly from 15.01 to 2.38, indicating an 84.14% conversion of FFA for the catalyst. The analysis using Gas Chromatography–Mass Spectrometry (GC–MS) validated the presence of significant fatty acid methyl esters (FAMEs), including methyl ester, methyl stearate, methyl linoleate, and methyl oleate. The findings indicate that SCG oil present a viable approach for transforming waste into valuable resources, supporting the principles of a circular economy and minimising reliance on non-renewable energy sources.