Electrolyzed water-soaking-assisted bio-enzymatic degumming of industrial hemp for cotton-type fiber production and spinnability optimization

During the degumming process of industrial hemp, a new pretreatment process was developed to overcome the difficulty of bio-enzyme penetration into the interior of the hemp, to allow reduced the enzyme dosage, thereby shortening the degumming time and reducing costs. This study uses an aqueous solution after electrolytic sodium bisulfite to soak hemp fibers, then degumming is performed by complex bio-enzyme to produce cotton-type industrial hemp fiber. Using the contents of reducing sugar, total sugar, and free phenolic hydroxyl groups as indicators, this study investigated the effects of the electrolysis bath ratio, the concentration of sodium bisulfite, and the soaking time on the bio-enzymatic degumming of industrial hemp. Furthermore, a response surface optimization analysis method was employed, with the breaking strength and fineness of hemp fibers as the response values, analyzing the influence of the interaction among various factors. Under the conditions of a sodium bisulfite concentration of 40 g/l, an electrolysis bath ratio of 1:50, and an immersion time of 24 h, the hemp fibers treated in this way, when further subjected to enzymatic degumming, released higher contents of reducing sugars, total sugars, and total phenols. The breaking strength of hemp fiber can reach 5.41 cN/dtex and fineness can reach 2.22 dtex, thus the optimization results are reasonable and feasible. The cotton-type industrial hemp fiber produced after degumming is blended with cotton according to 70/30 ratio by cotton spinning equipment. The test results showed that the yarn evenness of the hemp/cotton blended fine yarn was excellent, indicating that the 70/30 blend of hemp/cotton fiber had better spinnability.