Removal Of Cu-CIP Complexes By Combined Heterogeneous Electro-Fenton Based On Mofs And Electrocoagulation Process

Heavy metal-antibiotic complexes could cause more complex and harmful ecological effects than the original pollutants,thus affecting public health.Therefore,it is urgent to remove heavy metal-antibiotic complexes from water efficiently.In this study,a combined heterogeneous electro-Fenton and electrocoagulation method based on MOFs derived catalyst N-Co/Fe-PC were built for the removal of Cu-CIP complexes in wastewater.Various characterization methods were applied to study the morphology,composition,specific surface area and pore characteristics of the catalyst and the cathode.The effects of various influencing factors on the combined heterogeneous electro-Fenton and electrocoagulation method were explored.The mechanisms were also studied.The research contents and results were concluded as follows:（1）Co/Fe-MIL-101 with octahedral structure was prepared by one-step hydrothermal method at Co/Fe molar ratio of 1:2.N-Co/Fe-PC synthesized through co-calcination of Co/Fe-MIL-101 and melamine basically maintained octahedral structure,which was mainly composed of porous carbon loaded with Co/Fe alloys,nitrides and oxides.The BET curve and pore size distribution results showed that the specific surface area of N-Co/Fe-PC was 272.995 m~2/g and the microporous-mesoporous hierarchical porous structure provided more active sites,promoted the diffusion of reactive species and the catalytic performance.In addition,the pore structure of N-Co/Fe-PC was slit hole,which increased the specific surface area and provided more attachment points for the Co/Fe metal clusters.（2）A heterogeneous electro-Fenton method was built with N-Co/Fe-PC cathode and graphite anode.The influence of different factors on the performance of the heterogeneous electro-Fenton method was investigated,the results showed that when the calcination temperature was 700°C,Co/Fe ratio was 1:2,catalyst/carbon black ratio was 2:1,the current was 150 m A,the initial concentration was20 mg/L,and the p H was 5.6,the removal efficiency of Cu-CIP and TOC yielded at 65.9%and 56.0%,respectively in 120 min.The results of titanium potassium oxalate colorimetry,fluorescence spectroscopy,ESR and free radical quenching test indicated that H₂O₂,·O₂^-/·HO₂ and·OH^-were the active oxidation species in heterogeneous electro-Fenton.The mechanism of the oxidation species generation was proposed:the adsorbed O₂ molecules on the cathode surface were reduced to H₂O₂,and the Fe^Ⅱ/Co^Ⅱ和Fe^Ⅲ/Co^Ⅲredox cycles on the cathode surface catalyzed the activation of H₂O₂ to generate·O₂^-/·HO₂ radicals,which contributed to the degradation of Cu-CIP.According to the detected intermediates,the degradation pathway of Cu-CIP was proposed,including the ring opening and substitution of piperazine ring,the fracture of carboxyl and amino after ring opening,and the fracture of cyclopropyl.（3）The combined heterogeneous electro-Fenton and electrocoagulation was built with N-Co/Fe-PC cathode and aluminum anode.The optimized conditions obtained by the single factor experiment:under the conditions of current 100 m A,electrolyte 10 m M Na Cl,p H 7,and initial concentration 20mg/L,the removal efficiencies of Cu and CIP after 60 min were 99.78 and 97.61%,respectively.At the same time,the current,initial concentration,p H and time were used as the influencing factors,and the Cu and CIP removal efficiencies were used as the response values to conduct a response surface study.The interaction between different factors were explored,and the optimal value was predicted and verified by experiments.The degradation path was proposed:the ring opening and demethylation of piperazine ring,cleavage and demethylation of carboxyl group,hydroxylation substitution of piperazine ring,andβ-cleavage reaction of cyclopropyl group（-C₃H₅）,etc.During this process,Cu-CIP was oxidized to small molecular organic compounds and realized decomplexation,and Cu²⁺was re-released into water.At the same time,the small molecule degradation products of Cu-CIP and Cu²⁺were removed through the electrostatic adsorption and sweeping net capture process caused by the flocs produced by the anode（the main component isγ-Al OOH）In this study,a combined heterogeneous electro-Fenton and electrocoagulation method based on MOFs was proposed to realize the efficient removal of heavy metal-antibiotic complexes,and the reaction mechanism was proposed.It provided a reference for the synthesis of efficient heterogeneous electro-Fenton catalysts based on MOFs,and provided a new method and theoretical basis for the treatment of heavy metal-antibiotic complexes in wastewater.