Study On Treatment Of Organic Wastewater By Electrocatalytic Integrated With Persulfate

Persulfate advanced oxidation processes have been widely applied in environmental remediation in recent years,especially in the degradation of refractory organic contaminants.Electrocatalytic（EC）activation of persulfate（PS）is considered as one of the most efficient ways to generate sulfate radical(SO₄^?-).The subject adopts EC/PS system to treat organic pollutants,using electrolyte in homogeneous systems and iron-based metal oxide in heterogeneous systems as the catalysts,respectively.Construct a new homogeneous EC/PS coupling system（EC/PS-electrolyte）and a heterogeneous EC/PS coupling system（EC/PS-iron-based catalyst）.Using reactive brilliant blue（RBB）and tetracycline（TC）as target pollutants,the degradation performance of the coupling system was evaluated,and the reaction mechanism was studied.（1）The effectiveness and mechanism of TC degradation by EC/PS-electrolyte system are studied systematically.The RBB could activate PS,and NaNO₃ play a catalytic role.In the EC/PS-NO₃^-system,under the optimal conditions,the decolorization rate of RBB is92.50%.The scavenger experiments verified that both SO₄^?-and HO^?were the major active substances in the EC/PS-NO₃^-system.Besides,the degradation pathways of RBB in the reaction process were analyzed.（2）The iron-based catalysts,Fe₃O₄ and FeOOH,were prepared by a coprecipitation method,and they were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,and specific surface area（BET）.The catalytic performance of Fe₃O₄and FeOOH were compared.It has been proved that the Fe₃O₄ have higher electrocatalytic activity while the FeOOH has better adsorption performance.Therefore,a heterogeneous electrocatalytic system（EC/PS-Fe₃O₄）was used to degrade TC.Under the optimal conditions,the TC degradation rate was 84.95%within 60 min,and the degradation rate remained above 60%after 5 cycles of experiments.The scavenger experiments verified that HO^?was the major active substance in the EC/PS-Fe₃O₄ system.（3）MnFe₂O₄ bimetallic catalyst was prepared by coprecipitation method,and it was characterized by XRD,SEM and BET.A heterogeneous electrocatalytic system（EC/PS-MnFe₂O₄）was constructed to degrade TC.XPS analysis showed that the electron transfers between Mn（Ⅱ）Fe（Ⅲ）played an important role in activating PS.Under the optimal conditions,the degradation rate of TC reached 86.23%in 60 min,and the degradation rate was 75.13%after 5 cycles of experiments.The scavenger experiments verified that both HO^?were the major active substances in the EC/PS-MnFe2O4 system.The intermediate product of TC degradation was determined by LC-MS,and the degradation pathway of TC was presumed.