Efficient pretreatment of corncob using countercurrent process with p-toluenesulfonic acid for enhancing cellulose saccharification and lignin recovery

A countercurrent pretreatment strategy using p -toluenesulfonic acid (TsOH) was developed to improve the fractionation and enzymatic hydrolysis of corncob. Four pretreatment solvents were evaluated, and 50 % TsOH with three countercurrent pretreatment cycles showed the highest efficiency. After pretreatment, the cellulose content of the pretreated corncob increased to 76.7 %, and the removal of hemicellulose, acid-soluble lignin (ASL) and acid-insoluble lignin (AIL) was 88.1 %, 63.8 %, and 90.9 %, respectively. Subsequent enzymatic hydrolysis yielded an enzymatic digestibility of 79.1 % and a glucose recovery of 76.4 %. Structural analyses by SEM, XRD, and FTIR confirmed biomass deconstruction and cellulose enrichment. HSQC NMR analysis demonstrated that the recovered lignin was enriched in H-type units, suggesting promising potential for high-value valorization. This mild and effective TsOH countercurrent pretreatment provides a sustainable approach for lignocellulosic biorefining with strong prospects for industrial application.