Study On Electrocatalytic Oxidation Degradation Of Typical PPCPs By PbO₂-ZrO₂ Composite Electrode

In recent years,the production and use of Pharmaceutical and Personal Care Products has increased dramatically,which poses a serious threat to the ecosystem and human health.Due to its poor degradability in aquatic environment,chronic toxicity,mixed toxicity and continuous cumulative effect,traditional wastewater treatment technology cannot effectively degrade it.PbO₂-ZrO₂ composite electrode,as an anode material for electrocatalytic oxidation technology,has the advantages of high oxygen evolution overpotential,strong oxidation performance,long service life and so on,and is widely used in the electrocatalytic degradation process of all kinds of simulated pollutants.In this paper,PbO₂-ZrO₂ composite electrode was used to electrocatalytic degradation typical PPCPs simulated pollutants triclosan and diclofenac sodium.The main research contents are as follows:The PbO₂-ZrO₂ composite electrode was used in the treatment process of triclosan simulated pollutants.The effects of current density,initial triclosan concentration,and NaCl concentration on the triclosan removal rate were also investigated,and the optimal degradation process conditions for triclosan were determined as current density 30 m A cm^-2,initial triclosan concentration 10 mg L^-1,NaCl concentration 50 mmol L^-1.After 120 min of electrocatalytic oxidation degradation,the removal rate of triclosan can reach 83.87%.The removal rate of chemical oxygen demand（COD）was 60.23%.The analysis of the degradation process in the first 60 minutes found that the degradation process of triclosan follows the pesudo-first order kinetic model.Reusability tests show that the prepared PbO₂-ZrO₂ composite electrode has high reusability for the electrocatalytic oxidation degradation of triclosan.Under the optimal conditions,after 20 cycles of degradation,the removal rate of triclosan is still as high as 78.4%,which is only reduced by 5.47%.Through accelerated life test,weight-loss test and Pb ion concentration test,it was found that the PbO₂-ZrO₂composite electrode has a longer service life and higher stability in 3.5 wt%NaCl solution than the pure PbO₂ electrode.In addition,the reasons for the stability improvement of the PbO₂-ZrO₂composite electrode in a 3.5 wt%NaCl solution were analyzed.The PbO₂-ZrO₂ composite electrode was used in the treatment of diclofenac sodium simulated pollutants.The effects of current density,initial diclofenac sodium concentration,and the supporting electrolyte concentration on the removal rate of diclofenac sodium were investigated.The optimal degradation process conditions were determined as follows:current density 80 m A cm^-2,initial diclofenac sodium concentration 50 mg L^-1,supporting electrolyte Na₂SO₄ 0.15 mol L^-1.Under operating conditions,after 120 min of electrocatalytic oxidation degradation,the removal rate of diclofenac sodium was as high as 95.77%,and the removal rate of COD was 76.09%.The kinetics of the degradation process of diclofenac sodium was analyzed,and the results showed that the degradation process of diclofenac sodium was obeyed the pseudo-first-order kinetics model.Under the optimal process conditions,by deposition of ZrO₂ nanoparticles the electrocatalytic oxidation performance of the PbO₂electrode was increased 1.12 times,and the energy consumption of the PbO₂-ZrO₂nanocomposite electrode was reduced 57.5%under the condition that the COD removal rate was 60%.In addition,liquid-mass spectrometry was used to analyze the intermediates of diclofenac sodium in the degradation process and further propose possible degradation pathways.