Effect of complete dissolution in LiCl/DMSO on the isolation and characteristics of lignin from wheat straw internode

Abstract A modified cellulolytic enzyme lignin (CEL) protocol, named regeneration cellulolytic enzyme lignin (RCEL), was developed for the enhancement of carbohydrate removal and lignin extraction with short ball milling hours. The process of complete dissolution in lithium chloride/dimethyl sulfoxide (LiCl/DMSO) and regeneration in water prior to enzymatic hydrolysis were applied for improving the isolation of CEL from wheat straw internode. The removal of carbohydrates was enhanced with little structural changes of the isolated lignin. More than 90% of the lignin in the enzymatic residue of 4 h ball-milled/regenerated internode could be extracted by aqueous dioxane. The final lignin yield of RCEL based on Klason lignin in original internode reached 73.2%, which was 5.0% higher than that of CEL. The S / V ratio of isolate lignin was higher than that of lignin in situ and the increment of S / V ratio was occurred during both enzymatic hydrolysis and dioxane/water extraction steps. The analysis results of wet chemistry and 2D HSQC NMR showed that RCEL was structurally similar to CEL.