A novel cascade glycolic acid pretreatment-alkali degumming method for producing hemp fiber

Hemp fiber is a promising textile resource. Because hemp fibers contain high gum content, an efficient degumming method needs to be developed. This study proposed a novel cascade degumming process coupling organosolv pretreatment and alkali boiling. Glycolic acid was optimally selected as a pretreatment reagent. The cascade process achieved a high lignin removal rate (69.81%) and hemicellulose removal rate (84.83%). The degummed hemp fibers showed excellent properties (4.18 ± 0.99 cN/dtex and 8.34 ± 0.01 dtex). Moreover, the glycolic acid solution could be reused three times without purification. The glycolic acid pretreatment led to decreased consumption of alkali reagents by 96.15%. Furthermore, the effect of glycolic acid pretreatment on lignin removal was analyzed by chemical composition analysis, FTIR, XRD, TGA, GPC, and HSQC NMR analysis. These results indicate that the novel cascade degumming process is an efficient and eco-friendly degumming method.