Investigation of a homogeneous activating ozonation method in the rinsing procedure of cotton fabric dyed with reactive dye

The textile dyeing process requires the consumption of large quantities of water, which includes huge amounts of coloured wastewater. Usually the rinsing of dyed fabric and the treating of the dyeing house wastewater are separated. The two independent processes not only increase the difficulty of wastewater treatment but also increase the costs of the treatment. In this paper, the ozone/tetraacetylethylenediamine active oxidation technology was employed to rinse dyed fabric and to decolorise the rinsing wastewater simultaneously. The effects of the rinsing conditions on the decolorisation ratio and the chemical oxygen demand Cr value of treated wastewater, and the K/S value, colour difference, tensile strength and fastness of dyed samples were investigated. The results indicated that the decolorisation ratio of the rinsing effluent was greater than 80% and the chemical oxygen demand Cr value decreased more than 58% by the ozone/tetraacetylethylenediamine rinsing process compared with that of traditional rinsing processes. Furthermore, the curve of decolorisation kinetics was in good agreement with a pseudo-first-order kinetic model. In addition, the decolorisation mechanism was also discussed after ultraviolet-visible and ultra performance liquid chromatograph-mass spectrometry analyses of the degraded dye molecule.