The use of chitosan on hydrogen peroxide pretreated wool

Since chlorination is known to produce substantial pollution with adsorbable organo halogens (AOX) in textile wastewater, shrink resist treatments like the widely used chlorine/Hercosett process are no longer environmentally acceptable. The current trends towards the use of natural products have led to using polymers of natural origin such as chitosan as a substitute for synthetic polymers in wool finishing given its properties of biodegradability, bioactivity, and biocompatibility. The application of chitosan to wool in a zero-AOX aqueous treatment to improve shrink-resistance and dyeing properties was investigated. To enhance chitosan sorption, wool was subjected to hydrogen peroxide treatment prior to the chitosan treatment either under alkaline or acidic conditions. A staining technique was used to assess the presence and distribution of chitosan on wool. The alkaline hydrogen peroxide pretreatment promoted the diffusion of chitosan into the wool fiber leading to shrink-resist properties. To determine the influence of treatment conditions on the dyeing behavior, a low temperature (60C) was used. Dyed chitosan-treated wool, pretreated with hydrogen peroxide either at alkaline or acid pH, showed high values of exhaustion and fixation.