Simple and economic bleaching process for cotton fabric

Cotton fabric was bleached in a simple and economic process using a bleaching system composed of sodium chlorite and hexamethylenetetramine. Different bleaching trials were carried out keeping fixed sodium chlorite concentration and varying other reaction conditions. The obtained results reveal that bleached cotton fabric with satisfactory whiteness index and reasonable tensile strength can be obtained by treating the fabric at 95 °C in a bleaching bath containing 5 g/l sodium chlorite, 0.02 g/l hexamethylenetetramine and 1 g/l non-ionic wetting agent using a material to liquor ratio of 1:30. These optimum conditions lead to completion of the bleaching process in a reasonable duration of 2 h with minimum evolution of harmful chlorine dioxide gas. Lower concentrations of the activator hexamethylenetetramine were found to prolong the bleaching duration without getting satisfactory whiteness index. Higher concentrations of the activator were found to cause fast sodium chlorite decomposition without imparting bleaching effect to the fabric.