Study On The Effect Of Adsorption Property Of Carbon Felt Cathode On Degradation Of Tetracycline By Electro-Fenton Method

Nowadays,antibiotic residues have become one of the most serious environmental problems in the world,posing a great threat to human survival and health,as well as the balance and health of the ecosystem.As a kind of electrochemical advanced oxidation technology that can degrade antibiotic pollutants,electrofenton technology has attracted extensive attention due to its advantages of high oxidation efficiency,strong oxidation and no secondary pollution.The cathode material is one of the key factors to determine the degradation efficiency in electrochemical fenton system.The development of cathode materials with excellent properties has become a research hotspot.However,in the process of development,the influence on the adsorption properties of cathode materials has been rarely studied.In this study,in order to explore the influence of cathodic adsorption on the degradation of pollutants in the electrofenton system,four pieces of carbon felt with different adsorption properties were prepared by modifying carbon felt with the method of KOH alkali activation.Finally,the degradation pathway of target pollutant tetracycline and the adsorption and degradation effect of treated carbon felt on other pollutants were explored.The main contents of this study are as follows:1.In this paper,four pieces of carbon felt with different adsorption properties were prepared by KOH activation method at different temperatures:RCF,CF-700,CF-800 and CF-900.Adsorption removal rate two hours after the initial concentration of 80mg/L:CF-900 was 62.26%;CF-800 is 36.1%;CF-700 is 51.46%and RCF is7.54%.The adsorption capacity was significantly enhanced after activation.The results of morphological characterization,nitrogen adsorption and desorption experiments,XPS and FTIR analysis showed that the surface area of carbon felt increased from 1.257 m²/g to 15.583 m²/g after the activation of KOH.From RCF to cf-900,the proportion of-oh and C=O increased from 3.65%to 3.72%and 18.22%to19.92%,respectively.,and the total oxygen to carbon ratio（O/C ratio）increased from0.14 to 0.18.The results show that the whole adsorption process is more inclined to the chemical adsorption process.2.In the electrochemical degradation experiment of tetracycline,CF activated by KOH has better degradation performance of tetracycline.Using the first-order degradation model,the k value of CF-900 reached 0.0648min^-1,which was nearly 5times higher than that of RCF.Meanwhile,the k value of CF-700 obtained at 0.0473min^-11 was better than that of 0.0401 min^-11 CF-800.The order of the degradation efficiency is exactly the same as that of the adsorption property.This means that the carbon felt cathode with high adsorption performance can obtain higher electrofenton degradation efficiency.In the whole 8 h electrolysis process,the TOC removal rates of RCF,CF-700,CF-800 and CF-900 reached 78.2%,77.8%,72.4%and 83.9%,respectively.Carbon felt with good adsorption capacity has a better mineralization performance.Combined with the phenol adsorption and degradation experiment,we can find that carbon felt has a good adsorption and degradation effect on the intermediate product of tetracycline degradation,which can accelerate the mineralization of tetracycline.In addition,the current efficiency（MCE）reaches its peak at the initial stage of electrolysis.With the reduction of oxidizable intermediate reactants and the generation of refractory and insoluble by-products,the MCE value gradually decreases.Similarly,with the passage of electrolysis time,the energy consumption（EC）of carbon felt increases gradually.It also reflects that the intermediates of small molecules in the late mineralization experiment are more difficult to degrade.3.HPLC-ms analysis was used to determine the degradation path of tetracycline.The results showed that tetracycline gradually opened its ring under the attack of strong oxidizing hydroxyl radical,and was finally mineralized into water and carbon dioxide.In the adsorption and degradation experiments of other pollutants,the synergistic effect of adsorption and degradation was also obvious,and the degradation efficiency was compared to methylene blue>rhodamine b>methyl orange.The degradation efficiency of phenol>bisphenol A is closely related to its molecular structure,which is symmetrical and more difficult to be stable.