Novel system of corn cob pretreatment with acid–base mixture solution for enhanced enzymatic hydrolysis and reusability

Ionic liquids (ILs) are the key reagents for producing glucose. In spite of expensive ILs, the substitute of ionic liquid can be produced by reduced cost and high performance of the pretreatment process. For this work report, the characterization of corn cob pretreatments, 21.73 ± 0.06 CI value of XRD analysis of corn cobs pretreated with NaOH:HCOOH, is significantly lower than the 41.17 ± 0.13 CI value of corn cobs untreated. By considering delignification, the percentage of delignification of corn cobs pretreated with an acid–base mixture solution (NaOH and HCOOH) is significantly higher than the percentage of delignification of NaOH and HCOOH, suggesting that the enzyme digestibility can be enhanced with the increased amorphous lignocellulose of NaOH:HCOOH pretreatment. Interestingly, the 94.18 ± 0.11% cellulose conversion of NaOH:HCOOH is significantly higher than the 79.18 ± 0.11 and 75.21 ± 0.13 percentages of cellulose conversion of NaOH and HCOOH, significantly. Furthermore, the 85.02 ± 0.05% cellulose conversion of NaOH:HCOOH of 7 rounds of reused pretreatment is dramatically increased when compared with the 5.28 ± 0.12% cellulose conversion and non-detection of 7 rounds of reused pretreatment of NaOH and HCOOH. All of the results indicate that the NaOH:HCOOH reused solution has high performance for delignification and enzymatic accessibility by lignocellulose denatured with negative ions of OH⁻ and HCOO⁻, demonstrating that the cellulose quantity can be highly separated in the solid phase. This NaOH:HCOOH for pretreatment and reused pretreatment is first reported in this work.