Study On The Performance And Mechanism Of Antibiotics Degradation Based On BiVO₄ Photoanode Synergistic With Persulfate

Due to the widespread use of antibiotics,the detection types and frequency of antibiotics remaining in the environment are increasing,and the caused environmental problems are becoming more and more serious.Therefore,the research on the removal of antibiotics is imminent.Photoelectrocatalytic synergistic persulfate is a new type of high-efficiency coupling technology,which has good application prospects in the field of environmental management.In this paper,a catalytic system based on BiVO₄ and its composite photoanode synergistically with persulfate is constructed to study the performance and mechanism of the degradation of antibiotics in water,in order to provide a theoretical reference for the practical application of photoelectric catalytic synergistic persulfate degradation of antibiotics.In this study,BiVO₄ was used as the photoanode to construct a photoelectrocatalytic/Persulfate（PEC/PS）system.It was found that the removal efficiency of sulfamethoxazole（SMX）had been improved when PS was introduced into the PEC system,the degradation efficiency reached to 97.3%within 100 min and the degradation rate was 7.05 times higher than PEC system due to the synergistic effect of BiVO₄ and PS,and the PEC/PS system can maintain excellent degradation performance,the material has high stability.Electrochemical test and EPR test results show that PS can be used as an electron acceptor to consume some electrons and be activated to produce SO₄^·-,which not only improves the charge separation ability and charge transfer rate of BiVO₄ photoanode,but also enhances the degradation efficiency of SMX.Free radical quenching experiments show that h⁺is an important active species in PEC/PS system,·O₂^-、SO₄^·-and·OH can promote the degradation of SMX.The PEC/PS system was applied to study the removal performance of mixed antibiotics（SMX,CIP,TC）in deionized water and actual water.Compared with single pollutants,the degradation of SMX was inhibited to a certain extent,but the removal efficiency of TC and CIP was as high as 79.6%and 99.4%,especially in the actual water,the PEC/PS system had better catalytic degradation performance.LC-MS had been used to detect the intermediate products,detection results showed that SMX,CIP and TC had 7,11,and 19 intermediate products,respectively.Among them,SMX is mainly degraded through lose-SO₂,sulfonamide bond cleavage,oxidation,and lose-NH₂;CIP is degraded through piperazine ring opening,defluorination and dehydroxylation;TC is mainly degraded through dealkylation,dehydroxylation,ring opening and deamidation.Based on the above work,FeOOH cocatalyst was loaded on the surface of BiVO₄ by a simple one-step hydrothermal method.The photocurrent density of the modified photoanode at1.23 V vs.RHE is 3.2 mA/cm²,which is 2.6 times that of the blank BiVO₄.In addition,BiVO₄/FeOOH shows higher charge transfer kinetics than BiVO₄,and the promoted charge transfer process can reduce the recombination of photogenerated carriers on the liquid-solid interface,thereby improving the surface oxidation kinetics and reducing the recombination of electrons and holes.So that it has enhanced photoelectric catalytic performance.After the surface of BiVO₄ is loaded with FeOOH,the degradation effect of TC was improved compared with that of blank BiVO₄,and the degradation efficiency is 88.9%after reaction for 2 h.Through free radical quenching experiments,it is known that h⁺is an important active species,and·OH and·O₂^-together enhance the degradation effect of TC.After introducing 1 mM PS into the PEC system,the removal efficiency of TC can reach 99.6%within 1 h,and its degradation rate is 2.97 times higher than that of the PEC system.The excellent catalytic degradation performance is due to the combination of BiVO₄/FeOOH and PS.BiVO₄/FeOOH synergizes with PS to degrade TC and has good repeated use performance.In the PEC/PS system,h⁺is an important active species,and·O₂^-、SO₄^·-and·OH jointly participate in the degradation of TC.