Studied On Cu-Based Photocatalyst Activating Peroxymonosulfate For Pollutant Degradation

With the rapid development of economy and technology,a large number of sewage and waste water have been discharged in disorder,which makes the content of organic pollutants in natural water body increase continuously,especially the residue of antibiotic wastewater in the environment has become an urgent social problem to be solved.Advanced oxidation technology based on sulfate radical has been proved to be a strategy that can remove antibiotic wastewater pollution with high efficiency and low energy consumption,and has high practical application value.The sulfate radical produced by the decomposition of peroxymonosulfate（PMS）under external excitation has strong oxidation-reduction ability,long half-life and extensive p H adaptability.In recent years,the valence change of Cu-based photocatalyst in the process of activating PMS,which is similar to Fenton reaction,makes it have a very promising prospect in activating PMS to degrade pollutants.Unfortunately,due to the defects of rapid recombination of photogenerated electrons and holes,low utilization of visible light and insufficient active sites,a single Cu-based catalyst cannot effectively drive the Cu²⁺/Cu⁺cycle to activate PMS.Therefore,in order to solve the above problems,we use CuWO₄as a template to modify it by introducing oxygen defects,constructing heterojunction,doping other metal ions,and supporting quantum dot co-catalyst,so as to effectively improve its physical and chemical properties,and finally achieve excellent ability of activating PMS to degrade antibiotics.The specific research contents of this paper are as follows:（1）Bi₂MoO₆/CuWO₄type-II heterojunction photocatalyst was prepared by hydrothermal method and solvothermal method.Its phase composition,morphology,chemical composition,optical properties and other structural characteristics were studied by various characterization methods.Under the irradiation of visible light and with the addition of a small amount of PMS,the TC degradation experiments by Bi₂MoO₆/CuWO₄were studied.The results showed that the photocatalytic activity of BMO/CWO（4:1）for TC degradation was significantly enhanced,and its apparent rate constants were 1.95 times and 2.24 times of CuWO₄and Bi₂MoO₆,respectively.In addition,the effects of different initial p H values,different amounts of PMS and different inorganic anions on the degradation system were systematically studied,which showed that Bi₂MoO₆/CuWO₄had high stability,strong photocatalytic activity and wide p H adaptability.（2）Oxygen defect modified CuWO_4-x/Bi₁₂O₁₇Cl₂S-scheme heterojunction was prepared by hydrothermal method and coprecipitation method,and was used for photocatalytic activation of PMS to degrade TC.S-scheme heterojunction could effectively inhibit the recombination of photo-generated electrons and holes,promote the separation of charges,and maintain the excellent oxidation and reduction ability of the catalyst,thus further improving the degradation performance.Cu²⁺/Cu⁺cycle and oxygen vacancy also participated in the activation of PMS,which accelerating the production rate of active radicals,thus improving the removal efficiency of TC.The cycle experiment showed that CuWO_4-x/Bi₁₂O₁₇Cl₂S-scheme heterojunction equipped good stability and reusability,and could be applied to practical wastewater treatment.（3）Co-doped CuWO₄composites were prepared by hydrothermal method to realize the Cu²⁺/Cu⁺and Co²⁺/Co³⁺dual redox cycles for activating PMS.Subsequently,BNQDs were introduced by electrostatic adsorption method to prepare BNQDs modified Co-doped copper CuWO₄.CW/4Co/2BNQDs could degrade 94.8%TC in 30 minutes under visible light irradiation,and the corresponding rate constant was 2.7 times of CW/PMS system.Due to the ability of BNQDs of attracting holes,the charge separation efficiency in CW/4Co/2BNQDs samples was significantly improved and the average lifetime of carriers was extended.In addition,through the detection of TC intermediate products,the possible TC degradation pathway was reasonably proposed and the intermediate toxicity was evaluated.