Molecular dynamics interpretation of citric acid-water assisting mechanism in deep eutectic solvent to destruct agricultural residue and improve enzymatic hydrolyzability of cellulose

Efficient pretreatment is so far the bottleneck in lignocellullosic biorefinery. The deep eutectic solvent (DES) technologies presents promising potentials except for some practical tasks that prohibits its designs and applications. By introducing citric acid (CA) and water into choline chloride (ChCl)-glycerol (GL) system, a ternary deep eutectic solvent (TDES) composed with 1:1:1 ChCl:CA:GL (n/n) exhibited more outstanding pretreatment efficiency for sugarcane bagasse (SB), a representative agricultural residue, in respect to enzyme hydrolysis of cellulose than traditional binary DES pretreatment. After pretreated with TDES containing 20 % water for 60 min in 100 ℃, the SB residue released 96.4 % of glucose by 20 FPIU/g cellulose of enzyme hydrolysis. To understand the chemical mechanism of this phenomenon, the GROMACS was used to simulate the molecular dynamics (MD) of the model. This MD analysis could provide effective theoretical method to DES design and practical approach to develop green pretreatment technology of lignocellulose biorefinery. • New H2O assisted ternary DES constructed and applied in biomass pretreatment. • Assisting effect of citric acid and water on traditional enzymatic hydrolysis of agricultural residue. • Molecular dynamics simulation interpreting the role of acid and water in DES. • Hydrogen bond, interaction energy and radial distribution function are analyzed.