Effects of Urea on Hydrogen Peroxide Bleaching of Cotton Fabrics

In order to establish the bleaching process for cotton fabrics under the neutral condition, cotton fabrics were bleached by hydrogen peroxide with urea. It was revealed that hydrogen peroxide bleaching with urea showed the higher whiteness of bleached fabrics than that without urea at more than 70 degrees C. Tensile strength did not decrease after bleaching. Some radicals were observed by ESR measurement when urea was added into hydrogen peroxide aqueous solution. The effects of urea on hydrogen peroxide bleaching seems to be caused by active oxygen; hydroxyl radical (HO center dot), perhydroxyl radical (HOO center dot) and superoxide anion radical (O-2(center dot-)) as well as perhydroxyl anion (HOO). The residual hydrogen peroxide concentrations in bleaching baths were measured. When urea is added to the bleaching baths, the decomposition of hydrogen peroxide is accelerated even in the neutral bath.