The Stripping Of Reactive Dyes On Cotton Fabrics By Photocatalytic Method At Low Temperature

In the processes of textile dyeing, printing and finishing, varous faults such as disuniform shades, splashes etc. are often produced due to misoperating and encountering undesirable troubles. Conventional stripping processes, involving high bath-ratio and application of lots of chemcials with a potential risk at environment polluting, waste water resource and cost highly. Therefore, it is very important to develop green, environmentally- friendly stripping methodologies for error-correction of the faulty materials with energy-saving and less effluents discharge.In this work, a green, environmentally-friendly new stripping method was developed based on photocatalytic technology. The possibility of those stripping processes employed UV/water(UV/H2O), UV/oxidants (UV/H₂O₂, UV/K₂S₂O₈), UV/reducing agent (UV/Na2S2O4) and UV/nanomaterials(UV/TiO₂) systems were investigated in water-bath and fabric padding methods. The stripping parameters such as pH, the dosage of catalysts, temperature etc. were optimized by color stripping percent and the remained strength of fabric. The structures and morphologies of cotton fibers were tested and analyzed by FT-IR, XRD and SEM after stripping and before, and the possible mechanism of photocatalytic stripping was suggested. The results show that, the stripping of reactive dyes on cotton fabrics was obtained a satisfactory result in UV/H2O system except a little worse of the fabric strength, and the color stripping in water-bath was higher than that of fabric padding method. However, the color stripping efficiency was enhanced by the addition of various catalysts, which following as UV/K₂S₂O₈> UV/Na2S2O4> UV/H₂O₂> UV/TiO₂, and the remained fabric strength was improved significantly in UV/K₂S₂O₈ and UV/Na2S2O stripping systems. Furthermore, the photocatalytic stripping method can effectively remove the residual sizes etc. on the surface of fibers as well.