High Temperature/ZnO Activation Of Periodate For The Degradation Of Bisphenol A

As an endocrine disruptor,bisphenol A（BPA）affects the reproductive system and embryonic development,and has potential toxic effects on the aquatic environment.As an additive in the production of carbonate plastics and epoxy resins,BPA is widely used in the production of various industrial products,resulting in higher concentrations of BPA detected in water environments.Therefore,it is urgent to seek efficient and stable degradation treatment methods.Advanced oxidation processes are a new water treatment technology in recent years,mainly by generating active free radicals,such as the hydroxyl radical（·OH）and sulfate radical(SO₄^?-),to degrade organic pollutants in water.As one of the common oxidants in advanced oxidation technology,periodate is not easy to be activated due to its own stability and weak oxidation performance,which leads to its limitation in practical application.Therefore,a high temperature/ZnO system was established to activate periodate to remove pollutants in water.First,based on ultra pure water,the effects of initial concentration of periodate（PI）,initial dosage of ZnO,system temperature and common inorganic anions on the degradation efficiency and kinetics of BPA in heating/ZnO/PI system were investigated.The catalyst reuse experiment and the XRD characterization of the catalyst before and after the reaction were carried out.The results showed that the degradation of BPA in the system conformed to the pseudo-first-order kinetic model under different reaction conditions.With the increase of the initial concentration of PI and the dosage of ZnO,the degradation rate and apparent rate constant of BPA increased significantly.With the increase of the system temperature,the degradation efficiency and degradation rate were obviously accelerated.SO₄^2-、Cl^-have almost no effect on the degradation of BPA,and NO₃^-、CO₃^2-have a certain inhibitory effect on the degradation of BPA.After 5 times of repeated use of ZnO catalyst,the removal rate of BPA was all above 75.7%,and the crystal form did not change.A high heating/ZnO/PI catalytic oxidation system was established to degrade and remove bisphenol A from water.The main oxidation active substances and reaction mechanism of the high heating/ZnO/PI system were analyzed by changing the p H adjustment of the system,and conducting free radical quenching experiments,dissolved oxygen experiments and other analytical methods.It is clear that high temperature/ZnO has the ability to activate periodate.The high heating/ZnO/PI system can degrade more than 78%of bisphenol A within 60 min,and can remove 63%of TOC within 100 min.The degradation mechanism is that ZnO generates electron holes(ZnO_surfaceh⁺)and free electrons(ZnO_surfacee^-)at high temperature,which further react to generate various oxidative active species.It was identified that the main oxidative active substances changed dynamically under different p H conditions,and the existing oxidative active substances contained?OH、¹O₂and O₂^?-.Zn²⁺has weak catalytic ability,but ZnO plays the main catalytic role.In order to explore the performance of heating/ZnO/PI system in practical application,the effects of initial concentration of periodate（PI）,initial dosage of ZnO,system temperature and initial p H on the degradation efficiency of BPA were investigated based on the actual water.The results showed that the effects of the initial concentration of periodate,system temperature and initial p H on the degradation efficiency of BPA were consistent with the trend when ultrapure water was used as the background,but high dosage of ZnO would inhibit the degradation of BPA.The results of UV₂₅₄ verified the process that BPA was first decomposed into small molecular organics and then mineralized into inorganics.The results of three-dimensional fluorescence indicated that the organic matter in the actual water body could affect the degradation of BPA.This topic discusses the system of activating periodate by heterogeneous catalysts,and provides a theoretical basis for the application of this method in practical water bodies.