Valorization of sugarcane bagasse and spent coffee grounds for biodiesel production: a comparative study of solvent extraction methods

This study recognizes two significant agricultural residues, sugarcane bagasse waste (SBW) and spent coffee grounds (SCG), as viable feedstocks for sustainable biodiesel production. To optimize the oil extraction and transesterification steps, a comparative experimental framework was utilized, incorporating four distinct solvent systems (methanol, acetone, a methanol-acetone mixture, and n-hexane) alongside three NaOH catalyst concentrations (0.5%, 0.7%, and 1% w/w). The highest yield of biodiesel from SBW was 25% with a methanol-acetone mixture at 0.7% NaOH. For SCG, the highest yield was 37.5% with n-hexane at 0.5% NaOH. Characterization through UV-Vis spectrophotometry, FTIR, and GC-MS demonstrated that the produced biodiesel comprised high-purity fatty acid methyl esters (FAMEs). The main results of this study showed how important it is to match the composition of the feedstock, whether it is high in cellulose or lipids, with the right solvent polarity to guarantee that it works well. These results can be used to create low-cost renewable resources through specialized biodiesel processes that turn waste into energy. These processes can help with better waste management and more sustainable energy.