Comparison of Ozone-Based Cold Bleaching Processes with Conventional Pretreatment of Cotton

Abstract

ABSTRACT Alternative bleaching processes for cotton fabrics are presented in this study. The fabrics were pretreated with three different alternative methods which are termed here as cold bleaching process. These methods are ozone application alone (CP1), ozone-sodium persulfate application (CP2) and ozone-sodium perborate application (CP3). The results obtained from these cold bleaching processes were compared with the conventional pretreatment process (CP0) in terms of pretreatment efficiency, dyeability, and chemical/water/energy consumptions. It was found that the cold bleaching processes could be used as an alternative method for the pretreatment of cotton fabrics and the chemicals used in combination with ozone were important, as was ozonation duration. In addition to the evaluation of the pretreatment efficiencies, the differently pretreated samples were dyed with “madder” without using a mordant and without any previous extraction process, then the dyed fabrics were tested in terms of color yields (K/S), CIE L*a*b* color values, and washing/rubbing/light fastness properties. It was observed that the conventionally pretreated (CP0) samples exhibited higher color yields, darker shades. The fastnesses of the dyed samples were found nearly similar with the samples cold bleached and dyed. The chemical/water/energy consumptions during pretreatments were also compared for the different pretreatment processes and the benefits of cold bleaching processes come out from lower consumption of water, chemical and energy were illustrated. At the end of the study, the combination of ozone-sodium persulfate or ozone-sodium perborate were presented as alternatives for the purpose of cotton pretreatment.