Evaluating Hydrogen Peroxide Bleaching with Cationic Bleach Activators in a Cold Pad-Batch Process

Abstract

Bleach activators generate peracids in the presence of hydrogen peroxide and alkali that are more potent oxidizing agents than hydrogen peroxide under comparable bleaching conditions. The effects of key bleaching parameters (activator concentration, hydrogen peroxide, chelant, and pH) on the performance of cold pad-batch bleaching on cotton are investigated. Optimized recipes are determined for two cationic activators, N-[4-(triethylammoniomethyl) benzyl]ca prolactam chloride and 6-( N,N,N-trimethylammonio) hexanoyl caprolactam p-toluenesulfo nate, using a central composite experimental design. The laboratory optimized conditions are used for pilot plant scale bleaching of cotton knit fabric. CIE whiteness index values are calculated from measured reflectance data of the pilot scale bleaching and are in close agreement with those predicted by the experiment. A high level of whiteness ( CIE WI > 70) is achieved for both activators with 8-hour batching, and measurements of the degree of polymerization of the bleached and greige fabrics show little fiber damage in each case.