Study On Electrochemical Generation Of Persulfate And Antibiotic Degradation Based On Groundwater Environment

At present,groundwater pollution is serious in some areas of China,and antibiotics have been detected in groundwater.Antibiotics have high biological activity even at low concentrations,which will cause toxic effects on human and aquatic organisms.The chemical oxidation of persulfate(PDS)is one of the in-situ remediation methods of groundwater pollution,but the addition of PDS is easy to cause the increase of sulfate concentration in groundwater and the formation of secondary pollution.As SO42-is a common background ion in groundwater and one of the ions with great impact on environment and ecology,this study will use electrochemical method to oxidize SO42-in groundwater into persulfate,and then activate it into sulfate radical(SO4·-),so as to degrade antibiotics in groundwater.In this paper,electrode materials with high oxygen evolution potential were prepared,and the performance of oxidation generation of PDS was studied.Based on groundwater environmental factors,the influencing factors and generation mechanism of PDS were studied,and the degradation of tetracycline(TC)by in-situ generation of PDS was studied.TNA electrode was prepared by two-step anodic oxidation method,and self-doped Blue-TNA was prepared by electrochemical cathodic reduction after calcination.After cathodic polarization,Ti3+and oxygen vacancies were introduced into the TiO2 lattice.CV and EIS experimental analysis showed that the electrochemical performance of Blue-TNA was significantly enhanced,with excellent conductivity and lower electrochemical impedance.In the sulfate electrolyte,Blue-TNA anode was used for the in-situ generation of PDS.The results showed that Blue-TNA had good PDS generation performance,which was due to its anode high oxygen evolution potential and could inhibit the occurrence of oxygen evolution side reactions.The results showed that increasing current density and Na2SO4 concentration were beneficial to PDS generation and current efficiency.Electrolyte cations(NH4+ and H+)promoted PDS generation,while other coexisting anions(CO32-,HCO3-and PO43-)inhibited PDS generation to varying degrees.The effect of dissolved oxygen on PDS formation was ignored.In order to analyze the production pathway of PDS,masking experiments were carried out.The results showed that ·OH was an important precursor of PDS,and the formation mechanism of PDS was indirect oxidation of OH.An electrochemical system with Blue-TNA as anode and graphite felt(GF)as cathode was constructed,and the degradation effect and influencing factors of TC in the system were studied.Compared with perchlorate and nitrate,the degradation efficiency of TC in sulfate electrochemical system is more efficient,and the degradation rate can reach more than 90%in 30 min.It was also found that the coexisting anions HCO3-and PO43-had different inhibitory effects on the degradation of TC in the sulfate system,while Cl-promoted the degradation of TC,and humic acid had a strong inhibitory effect on the degradation of TC.EPR analysis showed that the electrochemical sulfate system could produce strongly oxidizing SO4and ·OH,and the synergistic effect of the two promoted the degradation of TC.The stability of the electrode was studied.The results of five cycles showed that the degradation effect of Blue-TNA on TC was not significantly reduced,and the electrode had good stability.This study showed that it is feasible to use Blue-TNA to generate PDS and SO4·-in situ to degrade pollutants in groundwater containing sulfate,which provided a certain theoretical basis for the development of green and efficient in-situ groundwater treatment technology.