Probing the mechanism of green solvent solubilization of hemicellulose based on molecular dynamics simulations

Extraction and solubilization of hemicellulose based on green solvents has become a technological hotspot affecting the efficient utilization of hemicellulose. In this paper, the solubilization effect of three ionic liquids and three choline chloride-based deep eutectic solvents for xylan was studied using molecular dynamics method. The solubility of xylan could reach 15 wt% in all six solvents and glucuronic acid xylan was the most soluble. Based on DFT calculations and molecular dynamics simulations, it was concluded that the solubilization mechanisms of the two green solvents were similar and were based on the strong hydrogen bond between the anion and the hydroxyl group on the xylan model. The ionic liquids with [CH3COO]- and choline chloride/urea (1:2) showed excellent solubilization results. The results showed that the hydrogen bonding network and strength increased with the increase of urea content. Meanwhile the addition of water formed a new choline chloride/urea (1:2)-water hydrogen bonding network, which enhanced the interaction of xylan with choline chloride/urea (1:2) and promoted dissolution.