Effects Of Adsorption Of Cationic Bleach Activators On The Performance To Bleach Cotton Fabrics

Low-temperature cotton bleaching process based on bleach activators has been developed in recent years due to the fact that the conventional peroxide bleaching process causes extensive energy consumption and environmental pollution, and also gives rise to severe chemical damage to cotton fibers. Cationic bleach activators are able to build activated peroxide systems which are effective for cotton bleaching under near-neutral pH conditions at low temperatures. In this project, it was proposed to investigate the adsorption of cationic bleach activators to cotton fabrics, and reveal the effect of adsorption cationic bleach activators on the low-temperature bleaching.In the first section, an activated peroxide system was built using N-[4-(triethylammoniomrthyl)benzoyl]caprolactam chloride (TBCC), hydrogen peroxide (H2O2) and sodium bicarbonate (NaHCO3) in molar ratio of 1:1.2:1.4 for cotton bleaching in rapid exhaustion process and cold pad-batch process. The experimental results indicated that the bleaching performance was significantly improved when the concentrations of TBCC, H2O2 and NaHCO3 were increased in a relatively low range. However, if the concentrations of TBCC, H2O2 and NaHCO3 were increased in a relatively high range, the bleaching performance was significantly decreased. This was probably due to the fact that TBCC and the compounds produced from TBCC were adsorbed onto cotton fibers.In the second section, morin was used to simulate natural dyes to explore how the TBCC-activated peroxide system remove the morin in cellulose substrate and solution. The experiment showed that the bleaching rate in homogeneous solution was little different from the one in cotton. When bleaching was performed at 50℃ and 70℃, it seems that the activated peroxide system was more effective for removing morin in solution than on fiber.In the third part, three kinds of N-[4-(tdimethylalkylammonio)benzoyl] caprolactam chlorides were synthesized to study the effect of the alkyl chain length to the performance of the bleaching through the adsorption of cotton fabrics. Experiment results showed that cotton fibershad better adsorption to the bleach activators with the longer alkyl chains. However, too looger alkyl chain resulted in steric hindrance in solution, that prevented peracids for cotton bleaching.