Ultrafast improvement of cellulose accessibility via non-dissolving pretreatment with LiBr·3H2O under room temperature

The development of sustainable and effective pretreatment methods to improve the accessibility of cellulose is of vital importance for its utilization. Herein, a novel high-efficiency pretreatment method based on lithium bromide trihydrate (LBTH) was established, which realized the fast improvement of cellulose accessibility under ambient conditions without dissolution of cellulose. The cellulose I structure of microcrystalline cellulose (MCC) was transformed into amorphous structure just within 5 min of LBTH pretreatment, and the crystallinity was reduced from 79.1 to 19.9%. After pretreatment for 30 min, the BET surface area of MCC increased from 2.1 to 125.9 m2/g. Particularly, the pretreated cellulose could be near-completely saccharified to glucose (98.3%) with ultra-low enzyme dosage (2.5 mg protein/g-glucan) just within 24 h, while the conversion of untreated MCC under the same conditions was only 16.7%. Additionally, this non-dissolving pretreatment is beneficial to the separation and recycling of LBTH, guaranteeing a clean and sustainable process.