Development And Application Of Capillary Electrophoresis Methods For The Analysis Of Three Different Structural Reactive Dyes And Their Hydrolysis Products

In the textile industry,reactive dyes are often used for the dyeing of cotton fabrics,and physical and chemical changes occur in the dyeing process,making the entire dyeing process complex and difficult to observe,resulting in poor dyeing reproducibility and other problems.On the other hand,when fixing the color under alkaline conditions,the reactive dye will undergo a hydrolysis reaction to generate hydrolyzed dyes that cannot be bound to the fiber,which will not only lead to a large increase in the cost of dyeing,but also these hydrolyzed dyes will be discharged into the environment with the dye wastewater,causing serious pollution.Therefore,detecting the content of reactive dyes and hydrolysates in the actual dyeing process is conducive to better understanding the dyeing process and hydrolysis of reactive dyes and improving the application performance of reactive dyes in the textile industry.In this paper,three reactive dyes with different structures,reactive blue 19,reactive black 5 and reactive red195,were used as analytes to prepare their respective vinyl sulfone and fully hydrolyzed reactive dyes,and an analytical method was developed to simultaneously separate and detect the concentrations of three reactive dyes and their ethylenesulfone and complete hydrolyzed reactive dyes by using a capillary electrophoresis（CE）equipped with ultraviolet detector.The full paper is divided into five chapters.Chapter 1 firstly introduces the basic concept of capillary electrophoresis,separation principle,separation mode and commonly used detectors;secondly,it introduces the classification of dyes and the application of reactive dyes in textile industry;then,it introduces the detection methods of reactive dyes commonly used at present;finally,it describes the purpose and significance of this research.In Chapter 2,a CE-UV method was developed for the simultaneous detection of three reactive dyes and their respective vinylsulfone-type and fully hydrolyzed reactive dyes.Firstly,the respective vinylsulfone-type reactive dyes and fully hydrolyzed reactive dyes of the three reactive dyes were prepared under weak and strong alkali conditions,respectively,and all nine forms of dyes were used as analytes in this experiment for subsequent analytical method investigation.Next,the types of additives that have the greatest influence on the separation of analytes were initially investigated,mainly organic solvents and cyclodextrin-based additives were examined.Then,we systematically investigated the concentration and p H of the background electrolyte（BGE）,the content of additives,and the separation voltage,and finally determined the optimal BGE system consisting of 20.0 mmol/L Na₂B₄O₇-10H₂O as background electrolyte,20.0 mmol/Lα-CD,15.0%（v/v）acetonitrile as additives,and 0.5 mol/L H₃BO₃solution to adjust the p H of BGE to 9.0 mmol/L.The p H of BGE was adjusted to 9.0 with 0.5mol/L H₃BO₃ solution;the separation voltage was+20 k V and the sample was injected for 4 s at 5 k Pa.Chapter 3 mainly verifies the practical application of CE-UV method to the detection of reactive blue 19,reactive black 5 and reactive red 195 in the monochromatic dyeing process,and calculates the concentration and dyeing rate of each reactive dye and hydrolyzed dye in the monochrome process.By comparing the detection results of each reactive dye at different detection wavelengths and 200nm by CE-UV method,it can be seen that on the basis of establishing the respective linear relationship equations at different wavelengths and then substituting them into the calculation,the results of the dyeing rate of each reactive dye at the two wavelengths are consistent within the error range,so the developed CE-UV method can be detected by 200nm instead of the detection wavelength of the reactive dyes,which lays the foundation for the detection of a variety of reactive dyes in the process of patchwork and dyeing.Then,the CE-UV method and UV-Vis method were used to detect the single staining samples,and the measured staining rate was compared,and it was found that the staining rate measured by the two methods was basically the same within the error range.Therefore,the results further show that the developed CE-UV method can be used to detect the concentration of each dye in the process of single dyeing of reactive dyes.Chapter 4 mainly verifies the practical application of CE-UV method to the detection of reactive blue 19,reactive black 5 and reactive red 195 in the color-matching and dyeing process,and calculates the concentration and dyeing rate of each dye and hydrolyzed dye in the process of patchwork.Then,the calculation results are compared with the UV-Vis method for the detection results of the actual dyeing samples,and it is found that the staining rate measured by the two methods is consistent within the error range.Therefore,the results further show that the developed CE-UV method can be used to detect the dye concentration in the actual spearing process of reactive dyes.Chapter 5 describes the conclusion and outlook of this study.