Effects on delignification of reusing 1-ethyl-3-methylimidazolium acetate and dimethyl sulfoxide in the pretreatment of corn cob for the enhancement of enzymatic hydrolysis in ethanol production

In this work, a method of reusing 1-ethyl-3-methylimidazolium acetate and dimethyl sulfoxide ([EMIM]OAc:DMSO) with additional DMSO has been developed for high delignification. From the results, the delignification in the first reuse of [EMIM]OAc:DMSO with at a ratio of 1:1 is 1.66-folds higher than that of the initial pretreatment. By considering a percentage cellulose conversion higher than 80%, [EMIM]OAc:DMSO in the ratio of 1:1 can be reused up to 17 rounds. Especially with the first reuse, 87.97 ± 0.11% cellulose conversion and 92.45 ± 0.14% ethanol yield can be determined according to the high enzymatic hydrolysis and ethanol fermentation. Furthermore, the decreases in the values of Lateral Order Index by FT-IR and Crystallinity Index by XRD demonstrate decreases in crystalline cellulose by 1.05- and 1.59-fold of original cellulose structure, respectively, suggesting a novel protocol and mechanism of pretreatment for high yield efficiency of cellulose hydrolysis to ethanol.