The Discharging Of Direct/Vat Dyes On Cotton Fabric By Photocatalytic Method

The discharge of cotton fabric is an important method in the printing process. Due to lots of chemicals are used in conventional discharge print which bring a lot of adverse impacts to people’s life as well as environmental pollution, therefore, it is important to develop green and ecological discharge print method for reducing the application of toxic chemicals and consumption of water resource、improving the quality of textile products and the energy-saving and low-emission goal of all textile industry.In this work, a green and new discharge method was developed based on photocatalytic technology. The effects of different photocatalystic system (UV/K2S2O8、UV/Na2S2O4、 UV/H2O2、UV/H2O) to direct dye on cotton fabric were investigated.Paraments such as the dosage of catalysts、pH、processing time、temperature、the concentration of dye were optimized by discharging percent、the remained strength of fabric and whiteness. Part of direct and vat dyes with different structures were went through discharging process. Then, the selection of the fittest background and surface dyes were discussed in this paper. The structures and morphologies of cotton fibers were tested and analyzed by FT-IR、XRD、TG-DTG-DSC combined thermal analysis、SEM. The results showed that:UV/K2S2O8had a better color discharge effect than others, both in acidic and alkaline condition. However, the effect on vat dyes was not quite obvious. Based on this investigation, a better color discharge condition was obtained both under the acidic and alkaline conditions. The chemical and cry stal structures of cotton fabric were somehow changed to some extent after photocatalystic process. Furthermore, the photocatalystic method can effectively remove the residual sizes etc. on the surface of fibers as well. The fiber turned to corrosion when photocatalystic process over a certain time.