Kaili Yang,Jinyu Shan,Xinru Wang,Jie Zhang,Guangming Tian,Dong Yang,Jie Yang,Jianhua Ma
Cellulose, as a naturally abundant and renewable resource, can support increasingly depleted non-renewable resources. However, its high crystallinity limits its wide application to some extent. Efficient dissolution of cellulose is a prerequisite for its high-value utilization. Investigating the dissolution mechanisms of cellulose solvent systems is a crucial strategy for achieving effective conversion of cellulose. This work utilizes three different cellulose dissolvent systems: sodium hydroxide/urea/H 2 O (NaOH/Urea/H 2 O), lithium chloride/ N , N -dimethylacetamide (LiCl/DMAc), and 1-butyl-3-methylimidazolium chloride/dimethyl sulfoxide (BMIMCl/DMSO) to dissolve cellulose, and explores the dissolution mechanisms involved with each solvent. Additionally, under the same coagulation bath conditions (deionized water), the structural and performance differences of regenerated cellulose fibers from different solvents were investigated. The results indicate that, apart from the structure and properties of the solvents, as well as external forces applied during the dissolution process, the extent of cellulose molecular chain degradation during dissolution (i.e., the reduction in degree of polymerization) significantly affects the mechanical strength of the regenerated cellulose fibers.
Molten salt hydrates (MSH) are efficient, environmentally friendly solvents widely used in polysaccharide dissolution and catalysis. This study thus exquisitely designed a series of acidic ZnCl 2 ·nH 2 O MSH systems with different hydration levels, and investigate their effect toward the selective fractionation of wheat straw components. With the increase in the hydration level of the acidic ZnCl 2 .nH 2 O MSH system, the hemicellulose removal rate gradually decreases, while cellulose retention improves. Among all, the ZnCl 2 ·6H 2 O system, under optimal conditions (5 % sulfuric acid, 100 °C for 20 min), achieved the best performance with 90.34 % cellulose retention, 93.32 % hemicellulose removal, and 34.07 % lignin removal, resulting in 80.55 % enzymatic digestibility of cellulose. The dissolution mechanism of hemicellulose in the acidic ZnCl 2 ·6H 2 O system was then elucidated by the computational simulations, where the results indicate that hemicellulose molecular chains exhibit greater extension and stability within the ZnCl 2 ·6H 2 O system, accompanied by stronger non-bonded interactions and a more uniform distribution of ions and water molecules. These factors enhance the interaction between the solvent and hemicellulose molecules, leading to higher solubilization efficiency. Further calculations revealed that hemicellulose has the strongest interaction energy with the ZnCl 2 ·6H 2 O/H 2 SO 4 system, confirming its superior selectivity for hemicellulose removal.
危险品化学品经营许可证（带存储）