Improving corn stover enzymatic saccharification via ferric chloride catalyzed dimethyl sulfoxide pretreatment and various additives

Abstract

A FeCl3-catalyzed dimethyl sulfoxide (DMSO) pretreatment was developed and used for enhancing corn stover enzymatic hydrolysis in this work. The results showed that the proposed pretreatment could not only selectively extract up to ˜100% of hemicellulose, but also remove a certain amount of lignin (˜36.4%), which finally resulted the pretreated corn stover became loose and easy for subsequent cellulase hydrolysis. Besides, the influence of various additives including Polyethylene glycol (PEG 600), Bovine serum albumin (BSA), and Tween 80 on pretreated solid enzymatic saccharification were also investigated and the result indicated that all tested additives presented positive effect to enhance the glucose yields. However, this improvement of glucose yield via extra additives was decreased as the enzyme loading increase or hydrolysis time extending. Furthermore, the addition of the above additives enable a reduction of enzyme loading by 50% or shortening of hydrolysis time to 12 h. The maximum glucose yield of this work was 90.2% (based on initial glucan in corn stover) and achieved when the pretreatment was performed at 120 °C for 45 min with 0.05 mol·L−1 FeCl3 and the enzymatic hydrolysis was performed at 50 °C for 72 h with 5% solid loading. It can be concluded that FeCl3-catalyzed DMSO pretreatment is an effective approach to remove hemicelluloses and lignin and disrupt the cell wall structure, leading to the improvement of corn stover enzymatic hydrolysis.