Study On Photocatalytic/Electrocatalytic Degradation Of Organic Pollutants And Simultaneous Reduction Of Carbon Dioxide

In recent years,with the rapid development of economy,the problem of environmental pollution is becoming more and more serious.The large amount of waste water and the continuous emission of greenhouse gases have posed a serious threat to human beings.In recent years,advanced oxidation process?AOPs?based on SO₄^·-is regarded as the most active and promising research field in wastewater treatment.At the same time photoelectricatalytic oxidation technology is also regarded as a promising technology for the degradation of organic pollutants.Although there are many reports about photoelectricatalytic oxidation of organic compounds,photoelectricatalytic reduction of CO₂ and removal of organic pollutants based on SO₄^·-advanced oxidation.However,it is rare that electrocatalytic techniques are coupled with advanced oxidation techniques to degrade typical organics.In addition,photoelectricatalytic oxidation technology and photoelectricatalytic reduction technology have not been combined to achieve the degradation of organic pollutants,but also the final product of the degradation of CO₂ into useful chemical products.Based on the this discussion,we prepared 3D hexagonal Co₃O₄ array to achieve electrocatalytic oxidation coupling with advanced oxidation degradation of anti-inflammatory drug diclofenac sodium?DCF?,and studied the selective sequence of SO₄^·-and·OH on the attack groups on DCF in solution.In addition,in order to remove organic pollutants and simultaneously recover CO₂,we prepared flower-like BiOBr anode materials and flake CuO cathode materials to construct photoelectric catalytic oxidation and photoelectric catalytic reduction system,so as to achieve efficient degradation of tetracycline?TC?and synchronous catalytic reduction of CO₂.The research of this paper can be divided into the following two aspects:First,a 3D hexagonal star Co₃O₄ electric anode was prepared by hydrothermal and calcination method,and coupled with persulfate?PMS?to achieve efficient degradation of DCF.Catalytic experiments confirmed that DCF can be rapidly degraded in the Co₃O₄/PMS system,and 97%of DCF can be removed in 15 min.Moreover,it is even faster in Co₃O₄/PMS+1.0 V system,and can be removed 99%in 10min.The results show that the electrocatalytic coupling advanced oxidation technology can achieve rapid removal of DCF.At the same time,we revealed the DCF conversion pathway in the presence of different free radicals by using the ultra high resolution mass spectrometry.By comparing the known reactivity of DCF with that of each free radical species,we have mechanically and systematically elucided the molecular level DCF conversion pathways induced by SO₄^·-and·OH.The test results show that SO₄^·-and·OH have different selectivity for the attack of groups in DCF.In the presence of both,the selectivity of SO₄^·-is higher,and it is more inclined to attack the aromatic ring and electron donating group?amino group?of DCF,while·OH is more inclined to attack aliphatic side chains and electron with drawing groups?carboxyl and chlorine atoms?.Secondly,flower-like BiOBr electrode and nanosheet CuO electrode were prepared by hydrothermal method.BiOBr electrode as photoanode and CuO as photocathode were applied in a reaction device at the same time to realize the PEC degradation of organic pollution TC coupled with CO₂ reduction.The catalytic experiments confirmed that the BiOBr electrode had the highest degradation efficiency in the PEC process,with the 2.5 h degradation efficiency of 68%,which was better than the separate electrocatalytic and photocatalytic processes.Similarly,in the CO₂reduction experiment,the efficiency of CO₂ reduction was the highest when the voltage was-0.7 V.After 2.5 h,the yield of methanol and ethanol reached 100.3?mol/L and12.0?mol/L,respectively.In addition,the simultaneous experiment of PEC degradation TC synergistic coupled with reduction of CO₂ showed that the degradation efficiency of TC was improved to 80%,and the production rates of methanol and ethanol were correspondingly increased to 125.9?mol/L and 26.5?mol/L,respectively.The experimental results show that there is a synergistic effect between PEC oxidation and PEC reduction,and the mechanism of synergistic catalysis is proposed.The current work not only provides good examples for PEC oxidation of organic pollutants and PEC reduction of CO₂,but also opens up a new way to simultaneously solve the problems of environmental governance and energy crisis and realize better utilization of organic pollutants.