Electro-Fenton Degradation Of Ciprofloxacin Hydrochloride:Based On FeS₂/ZIF-8@CNTs And Response Surface Optimization

As one of the advanced oxidation technologies（AOPS）,electro-Fenton technology can effectively degrade antibiotic wastewater,which has a wide range of sources and will cause harm to human beings and the environment if left untreated.Carbon nanotubes（CNTs）can be modified or prepared into composite electrodes to effectively enhance the catalytic activity,Metal-organic frameworks（MOFs）have the advantages of large specific surface area,high porosity and structural diversity are widely used in catalysis,and pyrite（FeS₂）has a high Fe²⁺content and can continuously produce H⁺in the presence of oxygen,which is beneficial to the electro-Fenton reaction.In this study,CNTs-doped ZIF-8 precursor material ZIF-8@CNTs was synthesized,and FeS₂ powder was synthesized by the solvothermal method.The synthesized precursor material was analyzed by scanning electron microscopy（SEM）for its morphological characteristics,and the fabricated FeS₂ powder material was analyzed by X-ray fluorescence spectrometry（XRF）and X-ray photoelectron spectrometry（XPS）for its structure and composition.Two materials were loaded onto carbon cloth to form an electro-Fenton cathode material for the degradation treatment of ciprofloxacin hydrochloride（CIP）wastewater,and response surface analysis was performed to analyze the significance between the influencing factors and to propose optimized conditions for validation.The results of the study are as follows.The prepared cathode materials were used to form heterogeneous electro-Fenton system to degrade CIP wastewater.The effects of different cathode materials,FeS₂:ZIF-8@CNTs loading ratio,Nafion solution addition,Fe²⁺loading,initial pH,initial voltage,and oxygenation rate on the degradation performance of CIP were investigated,and the results showed that:when the pollutant CIP concentration was 20 mg/L,the catalyst cathode material prepared with FeS₂:ZIF-8@CNTs loading ratio of 3:2,Nafion solution addition of 0.3 mL,Fe²⁺loading of 0.75 mg,initial pH of 4,initial voltage of-0.6 V,and oxygenation rate of 40 mL/min was used for the CIP,the degradation efficiency was 88.5%.In the stability test of the catalyst material,it was found that the catalyst degradation rate of CIP only decreased by 8%after five times of repeated use,indicating good stability of the catalyst.In the bursting experiment,it was found that the free radicals that mainly play a role in CIP degradation are hydroxyl radical（·OH）and superoxide anion（·O₂^-）.Response surface methodology tests using Design Expert 10 software yielded FeS₂:ZIF-8@CNTs loading ratio,initial pH,and initial voltage as significant factors among all influencing factors,a regression model was fitted based on a 3-factor,3-level Box-Behnken test,the optimal reaction conditions were FeS₂:ZIF-8@CNTs=1.297,initial pH value was 4.509,and initial voltage value was-0.479V.At this time,the CIP degradation efficiency was the highest 88.21%,and the actual degradation efficiency was 87.26%.