Bleaching of cotton to remove the natural colorants is required for all fabrics unless the fabrics are to be dyed in very dark shades. A variety of processes have been developed, including cold pad batch where the bleaching solution is padded onto the fabric and the fabric held at room temperature for an extended period of time, typically 16 – 24 hours, and hot bleaching where the fabric and bleaching solution are heated to elevated temperatures for shorter times, typically 30 – 60 minutes. The most widely known bleaching agents are sodium hypochlorite (cold pad batch) and hydrogen peroxide (hot bleaching). Although hypochlorite offers some advantages, i.e., is an
inexpensive oxidizer, has a brilliant white effects and high bleaching speed at room temperature, the formation of highly toxic chlorinated organic by-products (AOX) during the bleaching process has limited its use as AOX compounds are a potential hazard to drinking water resources. In attempts to reduce energy costs and increase productivity, researchers have focused on bleach activators to enhance process efficiency through the use of peracids. Peracids are produced directly in the bleaching liquor in presence of the cationic bleach activator. These peracids are environmentally safe, since they decompose to organic acids and oxygen. The decomposition products are biodegradable and do not form any toxic by-products. Peracids are stronger oxidizing agents than hydrogen peroxide and are more effective in bleaching at lower temperatures. In this study, the dyeing properties of knitted cotton fabrics, some of which were bleached with a commercial hydrogen peroxide receipe and the others bleached using cationic bleach activators in the same commercial bleaching receipe under lower temperature, were investigated with respect to CIE LAB colour values and bursting strength. The results show that, in comparison with the commercial hydrogen peroxide bleaching system, activator bleaching systems provide better strength and sufficient chroma values. Based on these results, cationic activators show significant promise in terms of both ecology and economy.
