Abstract:

In order to obtain an environmental friendly method for hemp degumming, the orthogonal experiment for lignosulfonates was designed based on glow discharge plasma in water. The optimum oxidative degradation conditions for lignin in hemp are as followed. The initial concentration of hemp solution of 210mg/L, the discharge power of 100W, and the discharge time is 20 min. Free radicals capture and pH experiments show that plasma discharge creates a large qantity of • OH free radicals and H+. This kind of acid oxidizing water is beneficial to degum hemp fibers by removing pectin, oxidative degrading lignin and hydrolyzing hemicellulose. The degraded prodrcts are characterized by scanning electron microscopy and chemical composition analysis. The results show that hemp fibers are splitted. The components of the lignin, pectin and hemicellulose of hemp fiber are decreased. The component of cellulose is increased to 73.08%. The pH and chemical oxygen demand (COD) results show that the residual water is acidic. Its COD value reanges from 1 500 - 2 000 mg/L.

Key words: hemp, ligninin, degumming, plasma, oxidation