Suppressing Effect of Chelating Agent on the Degradation and Discoloration of Fabric Dyed with Metal Complex Dye during Bleaching Process with Hydrogen Peroxide

Abstract

The effect of salts of ethylenediaminetetraacetic acid, EDTACaNa2 and EDTANa2, on the decrease in the damage caused to cotton during hydrogen peroxide bleaching of fabrics dyed with metal complex dyes was studied. The copper contained within the dye molecule greatly accelerated the decomposition of hydrogen peroxide. However, when EDTACaNa2 or EDTANa2 was added to the bleaching system, the decomposition of hydrogen peroxide was suppressed. The degradation of dyed fabric during the bleaching process was retarded because the chelating agents suppressed the catalytic action of the copper on the peroxide decomposition. Moreover, EDTACaNa2 suppressed the discoloration of the dyed cotton fabrics, without extracting the copper from the dye molecules on the fabric.