Valorization of fruit waste using DES pretreatment and hydrolysis over a heterogeneous catalyst for bioethanol production

Deep eutectic solvent (DES) has been tipped as an upcoming green solvent in biomass processing. In this study, choline-based DES was facilely synthesized and applied for the valorization of banana peel waste. The as-prepared DES shows an excellent performance in the pretreatment of banana peel waste by removing amorphous part of lignin and hemicellulose content as confirmed by SEM, XRD, and FT-IR analysis. Optimization of hydrolysis parameters over heterogeneous catalyst including reaction temperature, catalyst dosage, biomass loading, and reaction time was investigated to attain maximum of 72.9% of TRS yield. The functional moieties such as –SO 3 H, phenolic –OH, and –COOH groups on the surface of the catalyst play a vital role in the conversion of pretreated banana peel waste to reducing sugars by breaking the cleavage of glycosidic bonds into monomeric sugars. The catalytic hydrolysate was then fermented into bioethanol using Saccharomyces cerevisiae (baker’s yeast) and the presence of ethanol was confirmed with potassium dichromate method. As a result, DES pretreatment of lignocellulosic biomass will be effective with the combination of catalytic hydrolysis for the production of biofuel. Graphical abstract Choline-based deep eutectic solvent effectively deconstructs the complex structure of banana peel waste by reducing amorphous lignin and hemicelluloses, while cellulose remains intact. And also, utilization of MCAC favors the hydrolysis process by cleaving the glycosidic linkages on polysaccharides into maximum yield of monomers. The catalytic hydrolysate can produce biofuel via microbial fermentation.