The effect of combining mineral salt with ball milling for promoting enzymatic saccharification of cellulose

Abstract

Clean and efficient pretreatment is a critical process for producing cellulosic sugar platform for the production of advanced biofuels and chemicals. Combining a chemical treatment with ball milling is a relatively simple and environmentally friendly procedure, which may reduce the pretreatment time and energy consumption. Hence, in this study, the mineral salts (e.g. ZnCl2, ZnBr2, LiCl, and LiBr) were used to enhance the ball milling. Firstly, microcrystalline cellulose (MCC) as a model compound of pure cellulose was pretreated by mineral salt-assisted ball milling to investigate the effect of mineral salt and ball milling for promoting cellulose saccharification. LiBr showed the best effect to improve the effectiveness of ball milling pretreatment, and the glucose yield of saccharification reached up to 93.8 % under the optimal conditions. Then, corncob residue (CCR) as a distinctive starting material was pretreated by LiBr-assisted ball milling, and the corresponding glucose yield of saccharification (48 h) with enzyme dosage of 5 FPU/g-CCR was as high as 97.4 %. Characterization verified that, the effect of LiBr and ball milling could more effectively break hydrogen bonds and crystalline structure of cellulose, thus highly promoting the followed enzymatic saccharification without lignin removal and washing after LiBr-assisted ball milling pretreatment. This work can help to understand the effect of combining mineral salt with ball milling, which is beneficial to the development of clean and effective pretreatment approach for lignocellulose biorefinery. © 2024 Elsevier Ltd