Hydrotropic pretreatment on wheat straw for efficient biobutanol production

Highlights: • Wheat straw was pretreated by hydrotrope under different conditions. • Hydrotrope pretreatment could remove lignin from wheat straw effectively. • Hemicellulose can be removed by modified hydrotrope pretreatment. • Modified hydrotrope pretreatment enhanced polysaccharides digestibility. • Hydrotrope pretreatment provides potential for butanol production from wheat straw. -- Abstract: Pretreatment is an important upstream process that affects the economics of biofuels production from lignocellulose. Hydrotropic reagent sodium xylene sulfonate (SXS) was used in this study to treat wheat straw for efficient butanol production. Effects of temperature, time, SXS concentration on pretreatment were evaluated. In addition, a modified SXS pretreatment method with pH adjusted to 3.5 by formic acid was also conducted for efficient wheat straw conversion by removing hemicellulose fraction. Composition analysis, structure characterization, enzymatic hydrolysis and fermentation tests were conducted. The results showed that modified SXS pretreatment can be considered as an efficient method for improving wheat straw conversion efficiency for ABE production. The hexoses and pentoses in the enzymatic hydrolysates can be used by C. acetobutylicum for butanol production with 12.41 g L⁻¹ ABE produced, and the overall ABE yield of 100 g ABE/kg wheat straw was obtained. This study revealed that hydrotropic pretreatment provides an alternative potential to the conventional pretreatment processes for butanol production.