Green Degumming Technology of Hemp and a Comparison between Chemical and Biological Degumming

This paper provides an efficient and environmentally friendly biochemical degumming method for hemp fiber, which can address the problems of high temperature, high pressure, and extreme pollution of the traditional chemical method and the harsh reaction conditions of biological degumming, such as a long reaction time and pH. In the biochemical method, dilute solutions of alkali pectinase lyase and chemical additives were used to process the hemp fiber and then the fiber composition and structure were investigated. A comparison of the chemical, biological, and biochemical degumming methods shows that the biochemical method can replace the chemical one causing a similar degumming effect, both being better than the biological method. The best proportion of the biochemical solution was found to be 1.5% alkali pectinase lyase, and for chemical auxiliaries the total amount of alkali was ≤0.4% and the total amount of salt was ≤0.8%. The best conditions of the biochemical degumming process were determined to be a bath ratio of 1:10, reaction temperature of 60 °C, and the time of 60 min. After degumming, the composition of the fiber was as follows: lignin 3.69%, pectin 4.09%, hemicellulose 13.34%, and cellulose 78.87%. The fiber quality index of fibers dealt by the biochemical method shows that the linear density was 4.66 dtex, length was 35.6 mm, and fracture strength was 64.5 cN/dtex, which were higher than those treated by the chemical method. This shows that the biological degumming method can be a green degumming method with higher efficiency, lower consumption, and pollution, as well as has a broad application scope.