Mild sodium hydroxide pretreatment of tobacco product waste to enable efficient bioethanol production by separate hydrolysis and fermentation

Tobacco product waste (TPW) was considered as a novel and sustainable feedstock for second-generation ethanol production. TPW with over similar to 44% cellulose content was efficiently pretreated using concentrated (10% W/V) sodium hydroxide (SH) solution at different temperatures (0, 25, and 80 degrees C) and retention times (3 and 6 h). Subsequently, the pretreated biomass was subjected to separate enzymatic hydrolysis and fermentation by the filamentous fungusMucor hiemalis. Promising results were achieved following 3 h pretreatment of TPW at 80 degrees C, whereas the hydrolysis yield was substantially increased up to 91.3%. Besides, comprehensive tacking of key features of biomass (e.g., composition, crystalline structure, surface hydrophilicity and morphology, and accessible surface area) by semi-quantitative methods together with FTIR and SEM observations revealed major improvements occurred after mild SH pretreatment. Consequently, the maximum ethanol production as high as similar to 97% of theoretical ethanol yield was obtained, while it was only 44.4% from the untreated TPW. The implication of the work could possibly support TPW utilization for large-scale ethanol production in a tobacco-based biorefinery framework.

Automated summary

Efficient pretreatment of tobacco product waste (TPW) with concentrated sodium hydroxide solution and subsequent enzymatic hydrolysis by filamentous fungus Mucor hiemalis significantly improved ethanol production yield. The comprehensive analysis of biomass features post mild SH pretreatment revealed major improvements, leading to a high ethanol yield of up to 97% of theoretical yield. This work could potentially support large-scale ethanol production in a tobacco-based biorefinery framework.