Reusing ethanol-water and recovering residual gum in hemp degumming

Abstract

Traditional hemp degumming creates large volumes of effluent. Chemical treatment and discharge of the degumming solution is still a challenging task. In this work, ethanol-water solution was reused for hemp degumming and gum recovery was explored to reduce effluent volume and improve resource recovery. The influences of recycling times on fiber color, morphology, mechanical properties, thermal properties and dimensional properties were investigated. Also, the characterizations of the extracted lignin were conducted. The results indicated that pectin could be removed in every degumming cycle. Above 86% of cellulose could be achieved in the five degumming cycles and fiber tenacity increased with each consecutive cycle from 35.6 to 43.6 cN/tex. Most importantly, spherical lignin particles could be extracted from the solution of the last degumming cycle with an average diameter of 249.7 nm. This work contributes to green degumming of bast fibers, reducing degumming cost and value-adding of the lignin-rich residues.