Study On Dye-transfer Mechanism And Electrochemical Inhibition Technology Of Cotton Clothes Washing

In household washing,mixed washing of different colors of clothes can save washing time and energy consumption,improve the utilization rate of washing machines,and mixed washing has become a more common daily washing behavior.Washing cotton clothes which are easy to fade is often caused by the low fixation rate of dyes,and the fixation rate refers to the percentage of dyes that have been bonded with fibers in the dyeing process,which represents the utilization rate of dyes.At present,cotton clothing with low fixation rate has been gradually eliminated by the market,and cotton clothing with high fixation rate is favored by consumers because of its good color fastness to washing.However,after dyeing cotton clothes with dyes with high fixation rate,the problems of self-fading and dye transfer of light-colored cotton clothes will also occur in the process of mixed washing with light-colored cotton clothes,which seriously affects the washing quality of clothes and the user experience of washing machines.Therefore,it is very important to study the dye transfer problem in the process of mixed washing of dark cotton clothes and light cotton clothes with high fixation treatment,which is in line with the current trend of household washing research.However,most of the studies on dye transfer in shuffle washing are focused on the mechanism of discoloration caused by hydrolysis of reactive dyes and staining caused by physical adsorption of cellulose to reactive dyes,and there is no systematic study on the formation and adsorption mechanism of floating substances and the dynamic process of discoloration and dye transfer in real washing microenvironment.And an electrochemical hardware device is not develop to degrade that floating color substance so as to effectively solve the problem of dye transfer in the process of shuffling.Therefore,this paper will focus on the mechanism and electrochemical inhibition technology of dye transfer in the mixed washing of cotton clothes with high fixation treatment and light cotton clothes,specifically:Firstly,the mechanism of cotton fabric blending fading and dye transfer was clarified by simulated washing experiments.Four groups of reactive red dyes with different reactive group types of monovinyl sulfone,vinyl sulfone-monochlorotriazine and bis-vinyl sulfone were selected as screening dyes.The dark cotton fabric simulating the washing of dark cotton clothes was prepared by infrared dyeing small sample mechanism,and the dimethylformamide（DMF）extraction and stripping method was used to strip the four groups of colored fabrics,and the target dye screening was completed with high fixation rate as the screening index,and the washing fading and dye transfer behavior of reactive dyes with high fixation rate after dyeing cotton fabrics was studied.At the same time,the hydrolysis process of the target dye was detected by HPLC chromatography analysis,and the structure of the dye corresponding to the floating color substance washed off in the simulated washing device was identified by the control with the pure dye hydrolysate product.Experimental results show that the fixation rate of active red 195 is the highest,and it can be used as the target dye for experimental research.Chromatographic analysis showed that the floating pigment material shed by the dye on the dark fabric and the stained material adsorbed on the light-colored fabric were consistent,and both were double reactive group hydrolyzed dyes.The washing and fading of dark fabrics is mainly the desorption of the hydrolyzed dyes of the double reactive group,and the washing of the light colored fabrics is mainly caused by the physical adsorption of the desorption of the hydrolyzed dyes in the light colored fabrics.Secondly,the model modeling of the adsorption kinetics of active red 195 was carried out in the washing microenvironment,and the influence of washing parameters on dye desorption on dark fabrics and adsorption on light-colored fabrics was analyzed.Taking the desorption rate of the dye on the dark fabric and the adsorption rate of the light fabric on the dye as the index,and the washing temperature,washing liquor ratio and washing solution p H as the parameters,a single-factor experiment was carried out in the simulated washing device to discuss the influence of washing parameters on the desorption rate and adsorption rate.The experimental results show that when the mixing ratio of dark and light-colored fabrics is 1:1,the maximum desorption rate（95.45%）and maximum adsorption rate（53.59%）are reached when the washing temperature reaches 60°C,the maximum desorption rate（96.45%）is reached at 140:1,the maximum adsorption rate（36.87%）is reached at 100:1,the maximum desorption rate（102.23%）is reached when the washing solution p H is 14,and the maximum adsorption rate（50.27%）is reached when the p H is 7.At the same time,the response surface analysis showed that the washing temperature,washing liquor ratio and washing solution p H had significant effects on the desorption rate and adsorption rate of the dye.According to the results of parameter screening,the kinetic study of dye desorption and adsorption with washing time was carried out under three sets of washing parameters,and the kinetic model was fitted.The matching result verification experiment was carried out in the drum washing machine,and the verification results showed that the washing time-dye desorption curve was in line with the second-order exponential decay model,and the washing time-adsorption curve was in line with the pseudo-first-order kinetic model.The dynamic changes of desorption velocity and adsorption velocity can be effectively fitted using the second-order exponential decay model and the first-order exponential decay model,respectively.Through the model fitting parameters,it is found that the washing and desorption process of dye on dark cotton fabric and the process of desorption dye adsorption of light-colored fabric are very similar,which can be divided into fast stage and slow stage,and finally tend to equilibrium.Finally,with Ti/IrO₂ as the anode material and stainless steel as the cathode material,equipped with an electrochemical dye degradation device,the feasibility of electrochemical technology to solve the problem of dye transfer is studied,and simulation and real washing experiments are carried out.Under fixed washing conditions,the effects of voltage（X₁）,electrolyte concentration（X₂）and initial dye shedding concentration（X₃）on dye decolorization and anti-dye transfer effect were discussed by single factor experiments in the simulated washing-electrochemical degradation device,with the dye decolorization rate of the washing residue before and after the start of the electrochemical degradation device and the surfaceΔK/S_D of light-colored fabrics as indicators.The range of optimum parameter level of each degradation parameter was established.The regression model prediction of the three-factor three level experiment results was predicted by Box-Behnken experimental design（BBD）and response surface analysis,and the predictive model with the decolorization rate andΔK/S_D as the response values was obtained.At the same time,the interaction effect of each degradation parameter on the response value and the optimal degradation parameter are obtained in the direction of maximizing the response value,and the predicted parameters are verified in the drum washing machine.The experimental results show that the degradation parameters affect the dye decolorization rate in order:X₁,X₂,X₃,and the order of influence onΔK/S_D is:X₁,X₃,X₂.The order of influence of degradation parameter interaction on dye decolorization rate is:X₁ X₂,X₁ X₃,X₂ X₃,and the order of influence onΔK/S_D is:X₁ X₃,X₁ X₂,X₂ X₃.In the drum washing machine,the best degradation parameters for the dye decolorization rate andΔK/S_D to achieve the maximum value at the same time are:voltage=46 V,electrolyte concentration=10 mmol L^-1,and dye initial shedding concentration=0.49 mg L^-1.After three groups of washing parallel tests,the average absorbance of washing waste liquid after opening the electrochemical degradation device was 0.00267,and the average decolorization rate reached 90.80%,and the decolorization of washing wastewater was obvious.The meanΔK/S_D on the surface of the light-colored fabric reached 0.0124,and the amount of color string was effectively reduced.Therefore,under this optimized degradation parameter,the dye discharge in the washing wastewater can be effectively reduced,and the dye transfer process can be effectively suppressed.At the same time,according to the results of UV-Vis spectroscopy and FTIR infrared spectroscopy,the degradation mechanism of the shedding dye in the washing microenvironment is inferred.