| During the textile printing and dyeing process,some dyeing defects often occur due to various improper operations.Generally speaking,these fabrics need to be stripped.Traditional stripping methods have the disadvantages of high pollution and high energy consumption.Therefore,to study a green,environmentally friendly and efficient stripping method is of great significance to the Ecological processing.Among them,the photocatalytic stripping method is a new method with the advantages of simple processing and environmental protection.In this paper,stripping characteristics and mechanism of UV/TiO2 nano photocatalytic system for disperse dyes on polyester fabrics is mainly studied.Firstly,the effects of stripping solution pH,TiO2 concentration,K2S2O8 concentration,stripping temperature and stripping time on the stripping effect of polyester fabrics dyed with disperse dyes with different structures during UV/TiO2 photocatalytic stripping were discussed,the photocatalytic stripping process of six different structure disperse dyes on polyester fabric was optimized.At the same time,three different types of disperse dyes were selected and the optimized stripping process conditions were used to study the photocatalytic stripping kinetics of the polyester fabrics with different concentrations of the selected disperse dyes.In addition,explores the structure of azo disperse dyes on polyester fabric of nanometer photocatalytic mechanism of strip color,three kinds of free radical scavengers were selected to capture the free radicals generated in UV/TiO2 photocatalytic system,the effects of different pH,different temperatures,different oxygenation time,different TiO2 concentration,and different ultraviolet light time on the generation and capture of free radicals were explored.Then,UV-visible absorption spectroscopy and electron spin resonance spectroscopy were utilized to analyze the original solution and the reaction solution under different process conditions in the photocatalytic system were investigated.Finally,in this paper,Fourier transform infrared spectroscopy(FT-IR),desktop electron microscope,X-ray powder diffraction(XRD),thermal analysis(TG-DTG)and other testing methods were used to analyze the photocatalytic stripped fiber in disperse red 74 dyed polyester fabrics at different times.The results show that in the process of photocatalytic stripping,the pH value,TiO2 concentration,K2S2O8 concentration,stripping temperature and stripping treatment duration has an effect on the peeling effect of polyester fabrics,among which the pH of the stripping solution has the most significant effect on the stripping efficiency of the fabric,and the stripping time has the biggest impact on the strength retention of the fabric.After UV/TiO2 photocatalytic stripping treatment,the stripping efficiency of dyed polyester fabrics is mostly above 88%,and strength retention rate is almost above 90%.Studies on the photocatalytic stripping kinetics of disperse dyes with different structures on polyester fabrics show that the photocatalytic stripping kinetics of disperse dyes with different structures conform to the first-order reaction characteristics,and the photocatalytic stripping reactions are first-order reactions.In the experiment of capturing and characterizing the typical active radicals in the UV/TiO2 photocatalytic system,it was determined that hydroxyl radicals and superoxide radicals were generated in the UV/TiO2 photocatalytic system where three capture agents were used.In a certain range,the amount of free radicals tended to increase with the extension of the UV light time,and the structure as well as color of the capture agent greatly changes.What is more,the type of free radicals present in the solution also changed at different times,and the best process of different free radical generated in UV/TiO2 photocatalytic system was determined.In the process of stripping,the strongly oxidizing active substances such as hydroxyl radicals generated in the solution play a leading role.The structure and properties of dyed polyester fabrics changed slightly after photocatalytic stripping treatment.Infrared spectroscopy showed that after the photocatalytic stripping treatment at different times,The content of functional groups such as hydroxyl groups in the polyester fiber macromolecule chain increased,causing the stretching vibration peak to shift to a lower wave number.Desktop electron microscope analysis showed that after photocatalytic stripping treatment on polyester fabrics,magazines such as fiber surface oligomers could be removed,and the surface of the fibers would be slightly etched with the stripping time extending.Moreover,thermal analysis test results show that after photocatalytic stripping treatment,the thermal decomposition temperature of polyester fiber does not change significantly,and the residual rate after fiber decomposition is reduced.X-ray powder diffraction results show that with the prolong of photocatalytic stripping time,the intensity of the diffraction peak decreases significantly,and the width of the diffraction peak becomes narrower.As a result,the crystallinity of the fibers is reduced. |
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