Degradation Of PPCPs In Solution By Catalytic Ozonation In The Presence Of Manganese Based Catalysts

Pharmaceutical and Personal Care Products?PPCPs?are a new type of pollutants,widely used in human and veterinary drugs,agriculture and aquaculture,including antibiotics,estrogen,synthetic musk,sterilization disinfectant and detergent and anti-inflammatory analgesic,etc.Most PPCPs are characterized by complex structure,short half-life,strong polarity,difficulty in volatilization and degradation.The concentration range of PPCPs in conventional water treatment process is generally ng/L-?g/L,but it has long-term,potential and catastrophic effects on the environment.Therefore,it is necessary to use heterogeneous catalytic ozonation technology as advanced treatment to further ensure the safety of effluent water quality.In this study,a series of CuMn₂O₄ were prepared by coprecipitation method,hydrothermal method and sol-gel method,the degradation performance of benzophenone-3 was taken as the index to evaluate the influence of the calcination temperatures and Cu/Mn molar ratio on the catalytic performance of CuMn₂O₄.Secondly,the phase composition,the morphology and the specific surface area of CuMn₂O₄were characterized and analyzed by various surface characterization technologies.The results showed that CuMn₂O₄ had the best catalytic activity when prepared by coprecipitation,Cu/Mn molar ratio is 3:4and calcination temperature is 750?.At this time,the apparent reaction rate constant for removing benzophenone-3 in the first stage of the catalytic reaction is 5.15 times that of the ozonation alone.Finally,by investigating the effects of two free radical inhibitors,tert-butanol and sodium bicarbonate,on the catalytic ozonation by CuMn₂O₄,the free radical reaction mechanism of the catalytic oxidation and degradation of benzophenone-3 by CuMn₂O₄ was indirectly verified.In order to explore the yield of hydroxyl radicals in the heterogeneous catalytic ozonation and the mechanism of PPCPs degradation,further studies were carried out on catalytic ozonation by MnO₂-Co₃O₄to degrade 8 kinds of PPCPs in secondary effluent from municipal wastewater treatment plants.The results showed that the catalytic ozonation by MnO₂-Co₃O₄increased the apparent reaction rate constant of PPCPs by 1.29-8.76 times compared with the ozonation alone process.With the increase of[O₃]/[DOC]ratio,the removal effect of 8 kinds of PPCPs was improved.MnO₂-Co₃O₄ catalyst can increase the solubility of ozone.The exposure of ozone and hydroxyl radicals in the catalytic reaction are higher than that of ozonation alone,and its R_ct value is 2.07-14.25 times higher than that of ozonation alone.The chemical kinetic model can be used to predict the removal rate of PPCPs.The contribution of ozone oxidation and hydroxyl radical oxidation in the reaction process is calculated.The calculation results of the contribution of ozone oxidation and hydroxyl radical oxidation showed that the oxidation reaction of hydroxyl radical is the main degradation pathway of benzotriazole?BTA?and p-chlorobenzoic acid?p-CBA?.Quantitative structure activity relationship confirmed that PPCPs containing electron donating groups were easier to be oxidized and removed.