The mechanism for enhancing the hydrogen production yield from corn straw through the synthesis of deep eutectic solvents with [Emim][OAc] and 1,4-butanediol

To enhance the yield of biohydrogen production from corn straw, a methodology involving the synthesis of deep eutectic solvent (DES) using hydrogen bond acceptor [Emim][OAc] and hydrogen bond donor 1,4-butanediol and its application in the pretreatment was investigated. DES was prepared by mixing [Emim][OAc] and 1,4-butanediol solution with a concentration of 70% at a ratio of 4.7:100 (g:mL), followed by heating and stirring at 60 °C for 30 min. The optimal conditions for DES pretreatment were as follows: the liquid-solid ratio of the volume of DES to the mass of corn straw was 50:1 (mL:g), and the reaction temperature and reaction time were 121 °C and 1 h, respectively. The hydrogen yield was approximately 138.3 mL/g of corn straw. The comprehensive analysis outcomes derived from chemical analysis, FT-IR, 13 C NMR, XRD, TGA, and BET demonstrated that the hydrogen bonds within lignocellulose, the ester bonds between hemicellulose and lignin, the β -1,4 glycosidic bonds of cellulose and hemicellulose, and the β - O -4 bonds of lignin were disrupted, leading to the elimination of 86.79% of hemicellulose and 74.69% of lignin, thereby increasing the yield of hydrogen production from corn straw by 591.5%. The pretreatment efficacy of DES prepared from the fourth recycled [Emim][OAc] on corn straw did not deteriorate conspicuously. This study can offer a theoretical foundation for efficient hydrogen production from lignocellulosic biomass pretreated by DES.