Research On The Degradation Of Ofloxacin By Green And Clean Regenerative Electro-Fenton Proces

Ofloxacin,as the third generation of fluoroquinolone antibiotics,is widely used in health care,animal husbandry and other industries.Due to the poor biodegradability of ofloxacin,it is abundant in water,soil and sediments,affecting the environment.In recent years,electro-Fenton technology has received extensive attention due to its strong oxidizing ability,non-selectivity and high processing efficiency.In this paper,based on the traditional electro-Fenton,ofloxacin was used as the target pollutant to configure the simulated wastewater.The research was carried out from the perspectives of adsorption material filling and changing the aeration position,and the electro-Fenton system with green clean regeneration function was successfully designed.Subsequent experiments improved the electro-Fenton catalyst,further optimized the reaction conditions,increased the pH range of electro-Fenton reaction,and discussed the degradation mechanism of ofloxacin.The coupling of cathode internal aeration method and adsorption material is rarely studied in the electro-Fenton process,which provides a new idea for the future improvement of electro-Fenton and the removal of antibiotic pollutants.The specific research contents and results are as follows:In order to improve the removal efficiency of ofloxacin by the electro-Fenton process,the single factor experiment and orthogonal experiment were carried out from the cathode filler,aeration position,initial pH,current density and FeSO₄dosage,and the optimal process parameters were finally determined:the initial concentration of ofloxacin simulated wastewater was 25 mg·L^-1,pH=3,current density was 10 mA·m^-2,FeSO₄ dosage was 150 mg·L^-1,and clinoptilolite was used as the filler,which confirmed the excellent performance of the new electro-Fenton process in the removal of ofloxacin.Then the kinetics of ofloxacin degradation by the modified electro-Fenton process was studied,and the first-order kinetic equation was fitted:ln（C₀/C_t）=0.0519t-0.1461（rate constant=0.0519,R²=0.9786）.Under the optimum experimental conditions,the removal rate of ofloxacin was close to 100%.In order to improve the pH condition of electro-Fenton reaction and reduce the operation cost,FeOOH zeolite,Fe²⁺zeolite,FeOOH activated carbon and Fe²⁺activated carbon were successfully prepared by high temperature calcination method,and the catalysts were characterized by SEM and EDS.The adsorption experiments and kinetic fitting showed that the adsorption capacities q_e of the four catalysts were 0.773 mg·g^-1,1.287 mg·g^-1,0.732 mg·g^-1 and 0.773 mg·g^-1,respectively,which belonged to the pseudo-second-order kinetic model.The three influencing factors of pH,reaction time and catalyst dosage were studied,and the results showed that under neutral conditions,reaction time was 240 min,catalyst dosage was 20 g,and the removal rates of ofloxacin and TOC by FeOOH zeolite catalyst were 92.07%and 73.69%,respectively.The stability test and weight difference analysis of FeOOH-loaded zeolite catalysts showed that the removal rates of ofloxacin and TOC by FeOOH-loaded zeolite catalysts could still reach 76.9%and 55.3%after five tests,and the stability of the loaded substances was good.There are three main ways to remove ofloxacin by electro-Fenton method:quinolone group is oxidized and fluorine is replaced by hydroxyl group;piperazine and oxazine ring disconnected;OFLX occurred decarboxylation reaction,piperazine ring chain scission.