Development of a one-step process for desizing/scouring/bleaching cotton-based textiles

The technical feasibility of hydrogen peroxide (H2O2) activated sodium chlorite (NaClO2) in effecting concurrent desizing, scouring, and bleaching of loomstate all-cotton and cotton/polyester blend fabrics was studied. Activation of NaClO2 by H2O2 was performed in alkaline medium (pH 8 and 10) to avoid the troubles associated with evolution of chlorine dioxide. Bleaching was carried out under different conditions, and the bleaching effect of NaClO2/H2O2 system was assessed by monitoring the treated samples for degree of whiteness, percent loss in fabric weight, wettability, copper number, carboxyl groups, and tensile strength. Based on the results obtained, combined desizing, scouring, and bleaching of loomstate fabric could be achieved by treating the latter at 95°C with aqueous solutions containing 3 g/l NaClO2, 1 g/l H2O2, 2 g/l wetting agent and 10 g/l Na2HPO4 at pH 10 for 90 minutes using a material-to-liquor ratio of 1:20. A free radical mechanism was also reported to account for the bleaching action of NaClO2H2O2 system. The bleaching effect of the latter occurred via disintegration and destruction of foreign matter in cotton under the influence of various free radical species created during the treatment.