How is cellulose bleached?

China is rich in bamboo resources, but its application in textiles is very limited, mainly because bamboo fibers contain a large amount of hemicellulose and lignin. Alkaline cooking removes hemicellulose, but lignin is only removed by bleaching. A large number of fluorine-containing reagents are used in the traditional industrial bleaching process, which has caused great harm to the environment and human health. At present, bleaching technology is developing towards elemental chlorine-free (ECF) and total chlorine-free (TCF) bleaching, such as the use of O2, O3 and H2O2. However, these bleaches also have their own drawbacks. H2O2 is a better bleaching agent, but not an effective delignification agent. The delignification effect of H2O2 was successfully improved by the School of Textiles of Donghua University. They pretreated H2O2 with DMD (dimethyldioxirane) before bleaching to activate the lignin structure.

The pretreatment method is as follows: put the weighed fibers in a dish, add a little water and stir evenly, add acetone-water solution (V-propane: V water = 2:1), and add NaHCO3 at the same time to adjust the pH value to 7.0-7.5, and then stir again 10min, make it fully mixed, and finally add the dissolved potassium hydrogen persulfate preparation (2KHSO3, KHSO4, K2SO4) solution, stir evenly, put the fiber in a plastic belt, seal it and add it to a constant temperature water bath, after the reaction has reached the specified time , Take out the fiber and wash it with water.