Insight into the effective utilization of cotton spinning wastes from textile mills for the production of bioethanol

Sustainable feedstocks are one of the main issues with the manufacturing of bioethanol. The present work was focused to evaluate the potentials of 10 different cotton spinning wastes for bioethanol production using alkali pretreatment. The characterization results confirmed that the cotton spinning wastes are rich in cellulose (55–86 %w/w) content. Among the various alkali concentrations, temperatures, and times for pretreatment of cotton spinning wastes, 12 % NaOH, 5 °C, and 3 h resulted in optimum cellulose recovery and crystallinity reduction of 98 % and 88 %, respectively. The pretreatment rate of NaOH on cotton spinning wastes followed first-order reaction kinetics with an activation energy of 4.91 KJ/mol, t. Additionally, the optimal conditions for saccharification of the pretreated biomass (1 percent w/v of solid loading, 60 FPU/g of cellulose at 96 h) led to an approximately 82 % hydrolysis efficiency. The subsequent fermentation process by Saccharomyces cerevisiae resulted in the maximum of 65 % ethanol yield at 60 h. These results suggests that the cotton spinning wastes can potentially be exploited as feedstock for bioethanol production in order to meet the future energy demands.