Electrocatalysis-ozone Coupling Technology Research And Advanced Treatment Of Printing And Dyeing Wastewater

In order to find a technology that can efficiently treat printing and dyeing wastewater,an electrocatalytic-ozone coupling system is proposed in this paper.On the basis of ozone catalytic oxidation system,H₂O₂ is added to enhance the production of·OH.By combining with the electrochemical H₂O₂ system,the in-situ generation of H₂O₂ is realized,with cationic red X-GRL simulated dyeing wastewater as the target pollutant and determined that it has excellent advanced treatment capabilities.The Mg-Mn/GAC catalyst was first synthesized by the impregnation method,and the catalyst was used for ozone catalytic oxidation to degrade cationic red X-GRL.The COD degradation rate was used as an indicator,and the economic benefits were comprehensively considered.The preparation conditions were optimized to determine the impregnation method.The optimal preparation conditions are 80%of the theoretical value of KMn O₄ addition,450?of the calcination temperature,3 h of the calcination time,and 0.5 mol/L of the impregnation solution concentration.It was determined that the impregnation solution can be repeatedly impregnated when the volume loss of the impregnation solution can be immersed in the activated carbon.The catalytic performance of the prepared catalyst has not changed significantly.The orthogonal test results show that the optimal preparation conditions after repeated immersion are 6 h of immersion time,0.05 min of oxidant concentration,6.7 of m L oxidant volume,and 10 min of oxidation time.The catalyst prepared under optimal conditions was analyzed by SEM,EDS,XRD,and it was determined that the active components on the surface of the catalyst support mainly existed in the form of Mg Mn₂O₄.Set up hydrogen peroxide coupled ozone catalytic oxidation reaction system.The O₃+H₂O₂+Mg-Mn/GAC reaction system has the best TOC removal effect.It is found that the active site of Mg-Mn/GAC lies in the Mg-Mn bimetallic oxide,and Mg-Mn/GAC not only has the effect of catalyzing the ozone oxidation reaction,but also has the effect of catalyzing the overozonation reaction.Taking TOC degradation rate as an indicator and comprehensively considering economic benefits,the H₂O₂concentration,O₃concentration,HRT and other operating parameters were optimized,and the optimal H₂O₂concentration was determined to be 40 mg/L,and the optimal O₃ concentration was 33.7 mg/L.The optimal hydraulic retention time is 20 min.An electrochemical-catalytic system for in-situ generation of H₂O₂ was built,and the effects of ozone concentration,current density,electrolyte solution concentration,and hydraulic retention time on the production of H₂O₂ were studied under continuous flow in a solution containing sodium sulfate as the electrolyte.It is found that O₃ is beneficial to the reduction of O₂ to produce H₂O₂.The electrolyte solution concentration has little effect on H₂O₂ production.When the current density increases,the output of H₂O₂ increases,but the current efficiency decreases.As the hydraulic retention time is longer,the output of H₂O₂ increases.According to the above experimental results,an electrocatalytic-ozone coupling system was established.Taking TOC degradation rate as an indicator and comprehensively considering economic benefits,the optimal operating parameters were optimized during continuous flow operation,and the optimal O₃ concentration was determined to be 33.7 mg/L,the optimal catalyst dosage is 2 g/L,the optimal current density is 18.5 A/m²,and the optimal hydraulic retention time is 20 min.Under these conditions,the chromaticity drops from 23 degrees to 0.9 degrees after5 minutes of continuous flow operation.After the operation is stable,the TOC removal rate of the Mg-Mn/GAC enhanced electrocatalysis-ozone coupling reaction system was 63.1%,indicating that the constructed electrocatalysis-ozone coupling system had excellent pollutant removal performance.