Degradation Mechanism Of Chloramphenicol By Electro-Fenton Cathode Modified With Biomass Carbon

Chloramphenicol as a broad-spectrum antibiotic is widely used in livestock and poultry breeding.The content of chloramphenicol from antibiotic pharmaceutical wastewater and aquaculture wastewater is increasing.As the wastewater is discharged into the environmental,which causes the reproduction of antibiotic-resistant bacteria and even the existence of antibiotic-resistant genes.Therefore,it is important to effectively remove Chloramphenicol from environment to avoid their adverse health effects on humans.Electro-Fenton?EF?technology and bioelectric Fenton technology reduce oxygen to produce hydrogen peroxide in the cathode,and then produce hydroxyl radicals in situ,which could efficiently and no selective to treat wastewater of persistent organic pollutants.They are considered as an environmentally friendly electrochemical technology.However,it is sluggish kinetic process for oxygen reduction reaction,which seriously affects the degradation efficiency.Therefore,many researchers have introduced catalysts to reduce the oxygen reduction potential.In this article,N and O co-doped biomass porous carbon was prepared with the black soya bean,which is used to modify the EF cathode and the bioelectric Fenton cathode to investigate the degradation efficiency of chloramphenicol by EF and bioelectric Fenton.The specific experimental contents and results are as follows:?1?Biomass porous carbon is successfully prepared with black soya bean as precursor by simple carbonization and activation process.The porous carbon materials characterized by SEM,EDS and element mapping image,which composed of carbon,nitrogen and oxygen elements that are evenly distributed.The mass percentages of carbon,nitrogen and oxygen are 77.47%,2.01%and 20.54%,respectively.The porous carbon materials measured by nitrogen adsorption-desorption isotherm,XRD,XPS and Raman spectrum,which found the specific surface area,pore volume and pore size of carbon material are 663.6 m² g^-1?0.538 cm³ g^-1and 3 nm,respectively.The main types of carbon are graphite carbon and amorphous carbon.The forms of carbon binding are C-C,C-N,C-O and C=O,oxygen binding are C-OH,O-C=O,-COOH,C-O and H-O-H,nitrogen binding are pyridinic-N,graphitic-N,and oxidized N.?2?The EF cathode is modified by biomass carbon,which show that carbon catalytic material could produce H₂O₂ efficiently.Under the optimum conditions,1mmol/L Fe²⁺,p H=3,-0.5 V potential,the degradation efficiency of chloramphenicol reach 100%at 80 min and the apparent rate constant is 0.074 min^-1.The liquid chromatography-mass spectrometry is used to detect degradation intermediates of chloramphenicol.The determinate degradation intermediate products show that the degradation process of chloramphenicol is proposed that the pollutant underwent dechlorination,denitration and the cleavage of the benzenic ring forming small molecular components.?3?The bioelectric Fenton cathode is modified by biomass carbon,whose internal resistance is 147.27?lower than the carbon cloth cathode 55.26?,maximum power density is 261.08 m W/m²higher than the carbon cloth cathode 68.27m W/m².The average,maximum and minimum output voltage of NOPC cathode are higher than carbon cloth cathode cell.The concentration of H₂O₂ production by bioelectric Fenton modified with biomass carbon at 24 h is 0.065mmol/L,and the carbon cloth cathode is only 0.035mmol/L.When the bioelectric Fenton cathode is modified by biomass carbon to degrade Chloramphenicol,the degradation efficiency of 50 mg/L chloramphenicol is 36.38%at 24 h,and 1 mg/L chloramphenicol is 100%at 24 h.However,When the bioelectric Fenton cathode was carbon cloth,the degradation efficiency of 50 mg/L chloramphenicol is 28.45%at 24 h,and 1 mg/L chloramphenicol is 56.63%at 24 h.Compared with carbon cloth,the degradation efficiency of 50 mg/L chloramphenicol and 1 mg/L chloramphenicol at 24 h increased7.93%and 43.37%,respectively.?4?Comparing the degradation efficiency of different concentrations of chloramphenicol by EF and bioelectric Fenton,it is found that 50 mg/L chloramphenicol could rapidly degrade by EF,1 mg/L chloramphenicol could rapidly degrade by bioelectric Fenton,which indicated that EF is suitable for the degradation of high concentration chloramphenicol in pharmaceutical wastewater,and bioelectric Fenton is suitable for the degradation of low concentration chloramphenicol in natural water.