Pre-cationization of cotton fabrics: An effective alternative tool for activation of hydrogen peroxide bleaching process

Abstract

Hydrogen peroxide is a well-known environmentally safe bleaching agent for cotton fabric. However, bleaching of cotton based fabric with hydrogen peroxide requires alkaline medium (normally NaOH), stabilizer and either high temperatures or long dwell times. After bleaching and before dyeing, large amount of water is required for washing the residual un-decomposed hydrogen peroxide and the residual alkali. In this work, a new approach for bleaching cotton based fabric is postulated and investigated. The cotton fabric was scoured and cationized with NaOH and 3-cholor-2-hydroxy propyltrimethyl ammonium chloride (commercially known as CR-2000) either concurrent in one step process or separately in two step process. The scoured and cationized cotton fabric was then preceded for hydrogen peroxide bleaching. The cationic group on the cationized cotton fabric serves a dual function in the bleaching bath; the first is built-in catalyst for bleaching process and the second is powerful alkali site necessary for activation of hydrogen peroxide bleaching bath instead of NaOH. Three bleaching technique are utilized in bleaching of pre-scoured and cationized cotton fabric. These techniques are, exhaustion technique, pad-steam and cold pad-batch. The effects of cationization level, bleaching technique, bleaching parameters were systematically investigated. The fabric was monitored for strength properties, whiteness index and nitrogen content before and after the bleaching process. Results obtained show that, pre-cationization of cotton fabric provide comparable fabric whiteness in all technique investigated at much shorter reaction times and lower bleaching temperature in absence of NaOH. These results call for a breakthrough not only in bleaching of cotton based textiles but also in conventional detergent washing formulation.