Study On The Degradation Of Levofloxacin And Tetracycline By A Motional Bio-electro-fenton System With Fe@Co/GF Cathode

Antibiotics are utilized extensively and in large quantities,but they are not completely absorbed by organisms during use,and the majority of them re-enter the environment via excretion and other means.Although the total concentration of antibiotics in the environment is relatively low,they exist in a form that is relatively stable and is not easily transformed.The danger of antibiotics in the environment stems not only from their inherent chemical toxicity,but also from the fact that antibiotic misuse can lead to the production of resistance genes in the environment,which,when dispersed in the environment,pose a significant threat to public health and have been classified as a new class of environmental pollutant.Therefore,it is urgent to find an effective method to combat environmental antibiotic contamination.In this paper,the anode chamber of the BEF system was improved based on electro-Fenton（EF）technology and bio-Electro-Fenton（BEF）technology to construct a dual-chamber motional BEF（M-BEF）system,which has a larger loading area for microorganisms,higher electron transfer efficiency and more concentrated electricity production.Levofloxacin（LEV）and tetracycline（TC）were used as target contaminants to study their degradation performance.Specifically the following studies were carried out:（1）Preparation and characteristics of modified graphite felt cathodes（Fe@Co/GF）By activating ordinary graphite felt（GF）with KOH and then loading the activated GF with Fe@Co bimetal,a modified graphite felt（Fe@Co/GF）cathode with high catalytic activity was created.An electrochemical workstation was used to examine the cyclic oltametric characteristic curve and electrical impedance spectroscopy of Fe@Co/GF cathodes.A scanning electron microscope was used to examine the surface morphology of Fe@Co/GF,and the Brunauer-Emmett-Teller equation was applied to determine the specific surface area,pore volume,and pore size of Fe@Co/GF cathodes.And the main elements on Fe@Co/GF were confirmed to be Fe,Co and carbon by X-ray photoelectron spectroscopy,and Fe@Co/GF was determined by X-ray powder diffraction was used to determine the crystallinity of Fe@Co/GF.The morphology and other data show that the modified cathode has a larger specific surface area,bulk pores and more active sites,and the electrochemical performance tests demonstrate that the modified cathode has a stronger current response.（2）Degradation of LEV in EF system with Fe@Co/GF composite cathodeTo degrade levofloxacin and investigate the catalytic mechanism of Fe@Co/GF in the electro-Fenton system,Fe@Co/GF was used as the cathode of the EF system.It was discovered that Fe³⁺could be precipitated from the Fe@Co/GF cathode under acidic conditions,and that the Fenton reaction could still occur without an applied iron source.The degradation of ciprofloxacin（CIP）,an antibiotic comparable to levofloxacin,may imply the universal applicability of the Fe@Co/GF cathode in the treatment of CIP wastewater.A high-resolution tandem mass spectrometer was used to examine the relative molecular weights of the LEV degradation intermediates.Based on the relative molecular weights,hypotheses about the potential degradation pathways were made,with levofloxacin gradually mineralizing to small molecules in the presence of·OH and·O₂^-radicals.（3）Simultaneous degradation of levofloxacin and tetracycline in motional bio-electro-Fenton（M-BEF）system with GF composite cathodeIn the M-BEF system,the feed water of the anode chamber was TC wastewater,and considering the inhibitory effect of TC on activated sludge,the activated sludge was domesticated in the pre-experimental stage,and the feed water of the cathode chamber was LEV wastewater.In addition,the power production capacity of the M-BEF system with GF cathode and anodic oxidation capacity were investigated.And the effect of different experimental parameters on the removal rate of LEV in the cathode chamber was investigated.Possible intermediates in the degradation of TC were detected by HPLC-MS and speculations on the degradation pathways were made.The experimental results showed that the M-BEF system could achieve the simultaneous degradation of different types of wastewater in the anode and cathode chambers.（4）Simultaneous degradation of LEV and TC in the M-BEF system with Fe@Co/GF composite cathodeThe Fe@Co/GF cathode was used as the cathode for the M-BEF system to degrade LEV and TC wastewater simultaneously.The oxidation capacity of the M-BEF system under Fe@Co/GF cathode and the electricity production capacity of the system were investigated.The experimental results showed that the Fe@Co/GF cathode did not significantly promote the anodic oxidation and electricity production capacity of the M-BEF system,but mainly promoted the degradation of LEV in the cathode chamber.The microbial community in the anode chamber was examined using high-throughput sequencing technology,and the dominant strains of TC degrading bacteria and the main electricity producing bacteria in the anode chamber were analysed.