Promoting Effect of Sodium Chloride on the Solubilization and Depolymerization of Cellulose from Raw Biomass Materials in Water.

The development of a green system to solubilize cellulose from raw biomass is important, yet it is challenging because of the insolubility of cellulose in most solvents. Herein, a green NaCl-H2 O system is developed in which NaCl significantly enhances the dissolution and depolymerisation of cellulose from raw biomass. Nearly all the cellulose in the selected biomass types was dissolved and degraded into oligomers with molecular weights of 200-400 Da under relatively mild conditions. Cl(-) could interact strongly with the end OH group of the glucose unit in a 1:1 ratio, which resulted in the enhanced breaking of both inter- and intramolecular hydrogen bonds. In particular, the intermolecular hydrogen bond with an FTIR band at approximately v=3200 cm(-1) was disrupted significantly by Cl(-) . The FTIR band for a hydrogen bond between hemicellulose and lignin might appear at v=1636 cm(-1) , whereas this bond could be almost totally broken under hydrothermal conditions at 220 °C.