Preparation, characterization of light-colored lignin from corn stover by new ternary deep eutectic solvent extraction

The industrial lignin has shown great potential to replace some of petrochemical. But the deep color of lignin limits their application in high-value field. The extraction of light-colored lignin from lignocellulose still remains challenging. Here, we reported a strategy for rapid extraction of lignin from corn stover by using a new ternary deep eutectic solvent (TDES) composed of choline chloride (ChCl), formic acid (FA) and maleic acid (MA). The color feature and structural characterization of obtained lignin was comprehensively elucidated. The results revealed that the lignin streams had light color (brightness ISO 23.44 %) with a high yield (76.3 %), purity (93.5 %), low molecular weight (Mw 1544-2040 g/mol), and low polydispersity (PDI <= 1.76). The introduction of MA could reduce the destruction of lignin substructure during the treatment process and avoid the deepening of lignin color. Quantitative analysis of conjugated carbonyl and quinone carbonyl and semi-quantitative analysis of lignin by 2D NMR showed that temperature had a great influence on its structure.

Automated summary

A new method for rapid extraction of lignin from corn stover was reported in this study, and the color and structure of the obtained lignin were comprehensively characterized. The results showed that the lignin obtained by this method had a light color, high purity, and low molecular weight.