Construction Of Copper Tungstate P-n Heterojunction And Study On Catalytic Ultrasonic Degradation Of Orange Ⅱ Wastewater

Acoustic catalytic oxidation technology can improve the removal efficiency of organic pollutants through the combination of ultrasonic and catalyst.Among all kinds of catalysts,tungstate metal has become the catalyst with the most potential for development due to its advantages of low cost,high safety and wide distribution.CuWO₄is an N-type semiconductor with a band gap energy of 2.2-2.4 e V,low toxicity,and excellent photocorrosion and chemical corrosion resistance in neutral and acidic media.The previous research results of our research group show that CuWO₄,as an acoustic catalyst,also has a certain ability to degrade organic compounds.However,small band gap energy often leads to the reorganization of photocarriers.In order to obtain better acoustic catalytic performance,this problem needs to be effectively solved.Morphology regulation,ion doping,precious metal deposition and heterojunction construction.The construction of heterojunction is a widely used method nowadays.Therefore,in this paper,the acoustic catalytic performance of CuWO₄was improved by the construction of heterojunction,and the effect of reaction parameters on the degradation rate of the target degradation compound gold orangeⅡwas investigated.Firstly,Ag₂O/CuWO₄composite catalyst was constructed by coprecipitation method and characterized by scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）,UV-Vis diffuse reflectance spectroscopy（DRS）and specific surface area test（BET）.The catalytic ultrasonic degradation process of Ag₂O/CuWO₄composite catalyst was studied and optimized,and the optimal parameters were obtained as follows:When the Ag₂O composite ratio is 10%,the catalyst dosage is 1 g/L,the initial solution concentration of AO7 is 15 mg/L,the ultrasonic power is 500 W,and the ultrasonic time is 1 h,the solution reduction rate can reach 84.97±2.23%under the optimal parameters.Free radical capture experiments showed that the active substances generated during the ultrasonic degradation of AO7 by Ag₂O/CuWO₄include free radicals（·OH）,holes（h⁺）and superoxide anion radicals（·O₂^-）.Based on this,the degradation mechanism was proposed.Ag₂O/CuWO₄composite catalyst showed good stability and reusability in the process of ultrasonic catalytic decomposition.When the amount of K₂S₂O₈is 9mg,the degradation rate of AO7 can reach 99.01±0.04%by ultrasonic for 15 min,which can effectively reduce the cost of treating wastewater containing AO7.Secondly,Cu₂O/CuWO₄composite catalyst was prepared by coprecipitation method and characterized by SEM,TEM,XRD,XPS,DRS and BET.The catalytic ultrasonic degradation process of Cu₂O/CuWO₄composite catalyst was studied and optimized,and the optimal parameters were obtained as follows:When the composite ratio of Cu₂O is 40%,the amount of catalyst is 1.5 g/L,the initial concentration of AO7 is 10 mg/L,the ultrasonic power is 500 W,and the ultrasonic time is 1 h,the decomposition rate of AO7 can reach 92.59±2.28%under the optimal parameters.The active substances generated during the ultrasonic degradation of AO7 by Cu₂O/CuWO₄composite catalyst include·OH,h⁺and·O₂^-.The Cu₂O/CuWO₄composite catalyst shows good stability and reusability in the ultrasonic degradation process.Adding 5 mg K₂S₂O₈can effectively improve the degradation rate of AO7 on Cu₂O/CuWO₄composite catalyst,and the degradation rate of AO7 can reach 97.8±0.09%in 1 h by ultrasonic.In this paper,by constructing heterojunction,the recombination rate of e^--h⁺pair is effectively delayed,the acoustic catalytic activity of the composite catalyst is improved,and the ultrasonic catalytic degradation rate of AO7 by CuWO₄series composite catalyst is significantly improved.The results of this study provide a research basis for further promoting the research and development of CuWO₄based catalysts and the practical application of acoustic catalytic degradation technology.