Research On Electrochemical Cathode Enhanced Degradation Of Sulfamethoxazole From Aqueous Solution In Coupling Cobalt(?) With Persulfate

With the rapid growth of China's economy and the improvement of people's living standards,typical trace organic pollutants represented by pharmaceuticals and personal ca re products?PPCPs?have been frequently detected in the water environment,attacting widespread attention from scholars at home and abroad.Because it is difficult to be completely removed by the traditional water treatment process,advanced oxidation technology has become a research hotspot for the treatment of refractory organic pollutants with its rapid,non-selective and thorough oxidation of pollutants in the environment.In the experiment,the biodegradable antibiotic drug sulfamethoxazole?SMX?was used as the target pollutant to study the feasibility of electrochemically increasing the persulfate-Co???coupling system for removing sulfamethoxazole.Meanwhile,the effects of various experimental factors on its degradation were systematically analyzed and the reaction mechanism was investigated at last.By comparing the experimental results of different methods,compared with the Co???alone,Electrolysis alone,the E-PDS system and the PDS-Co???system,the E-Co???/PDS system has the highest degradation rate of SMX and its reaction rate constant.Furthermore,the system was optimized by the comparison of different electrodes.Compared with the titanium-plated platinum cathode,the activated carbon fiber as the cathode is more conducive to the oxidative degradation of the target pollutants in the reaction system,which significantly improves the degradation rate and salinity of the system.The degradation of SMX by E-Co???/PDS-ACF system?ie ECP-ACF system?was systematically discussed with activated carbon fiber as the cathode.The degradation of SMX by PDS alone,electrosorption?E?ACF??,PDS-Co???system,E?ACF?/PDS system,E?ACF?-Co???system and ECP-ACF system was discussed respectively.The results show that the ECP-ACF system is far superior to other systems in terms of degradation efficiency,salinity,reaction rate constant and persulfate utilization rate,which further proves that the system is more conducive to the degradation of SMX.The effects of persulfate concentration,cobalt ion concentration,current density,initial pH,electrolyte concentration,anion and water quality on the degradation of SMX in EPC-ACF system were systematically analyzed.The results illuminated that the removal rate of SMX increased with the aggrandizing of persulfate concentration,cobalt ion concentration and current density.The initial pH had no significant effect on the oxidative degradation ability of the system,and SMX could be effectively removed in the range of pH=2⁹.The electrolyte sodium sulfate?Na₂SO₄?had a certain impact on the system.In the range of 5²5 mM,the degradation rate of SMX rised with the increasing of the electrolyte concentration,however,the reaction would be inhibited when the electrolyte concentration was further increased.NO₃^-had little effect on the EPC-ACF system,while Cl^-and PO₄^3-could significantly accelerate the reaction rate.Additionally,the result indicated that the removal rate of SMX was higher than 90%when using tap water,surface water or ultrapure water as the reaction solvent in the EPC-ACF system,and the effect of tap water was the best.In the process of mechanism investigation,the repeated use of activated carbon fiber electrode in EPC-ACF system was investigated.The result indicated that the cathode electric field can effectively protect the structure of activated carbon fiber,so that it can be reused.The trapping experiment,which mainly occuring on the surface of ACF fibers,was conducted by dosing a radical scavenger such as methanol,tert-butanol or phenol.The experiment result showed that the presence of hydroxyl radicals and sulfate radicals was the main reason for the degradation of SMX,in which sulfate radical played a dominant role.