Degradation of pectic polysaccharides by ascorbic acid/H₂O₂–pectinase system and its application in cotton scouring

Untreated cotton usually needs to be scoured to remove hydrophobic pectin and wax for the demands of subsequent processing such as dyeing and finishing. Pectinase can degrade pectin on cotton fibers, but the catalytic efficiency is not particularly high. This study developed a new scouring method for cotton fabrics by pectin hydrolase combined with an ascorbic acid (VC)/H₂O₂ Fenton-like system. The GPC results showed that water-soluble pectin (1969.2 kDa) could be degraded into 10.6 kDa within 30 min through pectinase with VC/H₂O₂. The FTIR results suggested that VC/H₂O₂ breaks the ester bonds on water-soluble pectin. The results of XPS demonstrated that the α-1,4-glycosidic bonds of pectin could be degraded more effectively through VC/H₂O₂ oxidation and pectinase hydrolysis. The fabrics scoured with VC/H₂O₂–pectinase exhibited a reduction in wetting time (from > 200 to 8.04 s) and an increase in vertical wicking height (from 0.1 to 6.70 cm) in comparison to the fabrics treated with pectinase. The pilot-scale machine experiments yielded satisfactory performance with VC/H₂O₂–pectinase scoured fabrics, suggesting that VC/H₂O₂–pectinase scouring has potential for practical application. The cotton fabric scouring by VC/H₂O₂–pectinase is a simple and efficient method with the advantages of mild treatment conditions, less damage to cotton fabrics and environmental friendliness.