Effects of LiCl/DMSO dissolution and enzymatic hydrolysis on the chemical composition and lignin structure of rice straw

• Rice straw with 1 h ball milling can be completely dissolved in 8% LiCl/DMSO.
• About 1/4 of lignin lost after ball milling and LiCl/DMSO dissolution/regeneration.
• The efficiency of enzymatic hydrolysis was effectively improved.
• The structure of lignin in stem is rather different with that in leaf.
• It is probably that straw lignin in LCC has a higher degree of condensation.

The exploration of solvent system to completely dissolve lignocellulosic biomass is of great important for the development of biomass based materials and chemicals. Dimethyl sulfoxide containing certain amount of lithium chloride (LiCl/DMSO) was proved an effective solvent system for the dissolution of ball-milled wood. In this paper, four samples of rice straw, internode (stem without node), stem, leaf (leaf and sheath) and whole straw, with and without 1 h of ball milling treatment, were used to investigate the effects of their dissolution in LiCl/DMSO solvent on the chemical composition of regenerated and enzymatically hydrolyzed materials. Because of the structural difference from wood, samples expose d to 1 h of milling were almost completely dissolved. The chemical nature of the regenerated material and of residual after enzymatic hydrolysis of rice straw was analyzed and the susceptibility of this rice straw to the enzymatic hydrolysis was evaluated.