Lignocellulosic biomass is a promising feedstock for bioethanol production, but its recalcitrant structure requires efficient pretreatment to improve sugar release. This study valorized tamarind shells, an abundant agricultural residue, for bioethanol production through pretreatment with two deep eutectic solvents (DESs): a ternary DES containing choline chloride, ethylene glycol, and p-toluenesulfonic acid, and a binary DES containing urea and monoethanolamine. Pretreatment significantly modified biomass composition, with the ternary DES removing hemicellulose completely, while the binary DES reduced lignin and partially solubilized hemicellulose. Enzymatic saccharification increased reducing sugar yields from 31.80 mg/g in untreated shells to 183.94 mg/g and 170.50 mg/g for ternary and binary DES-pretreated biomass, respectively. Fermentation of the hydrolysates produced ethanol concentrations of 91.48 mg/g for the ternary DES, and 85.76 mg/g for the binary DES, representing 6.9and 6.4-folds increase over untreated shells (13.34 mg/g). These results demonstrate that DES pretreatment effectively enhances sugar release and ethanol production, highlighting tamarind shells as a sustainable feedstock for bioethanol.
Arshad et al. (Thu,) studied this question.