Study On The Degradation Of Ciprofloxacin Wastewater By Iron Oxide Activated Persulfate

Ciprofloxacin is a widely used fluoroquinolone antibiotic,widely used in industries such as medicine,pharmaceuticals,animal husbandry,and aquaculture.Due to the abuse of antibiotic drugs,significant residues of ciprofloxacin have emerged in water bodies,soil,and even animals and plants,posing potential hazards to the ecological environment and human health.The Advanced oxidation process based on persulfate has attracted extensive attention due to its advantages of low cost,simple operation and low re pollution rate.Iron based materials have the advantages of easy recovery and high recyclability,making them a high-quality choice for activating persulfate catalysts.This paper prepared two types of iron oxides and used them to activate the degradation of ciprofloxacin by persulfate（PS）.The specific content is as follows:（1）Using ciprofloxacin hydrochloride（CIP）as the target pollutant,a water bath drying method was used to obtain Fe₃O₄-1 and Fe₃O₄-2 catalysts by adding 20 ml of deionized water in the ratio of 1 g Fe SO₄·7H₂O,stirring and dissolving,and adjusting the p H values to 10 and5 respectively.（2）Characterization of Fe₃O₄-1 and Fe₃O₄-2 was carried out using X-ray diffraction（XRD）and Fourier transform infrared spectroscopy（FTIR）methods.The results show that the main component of both catalysts is Fe₃O₄,and Fe₃O₄-1 is a cubic Fe₃O₄with high purity;Fe₃O₄-2 is a cubic anti spinel structure Fe₃O₄with a moderate to high purity.Both infrared spectra show O-H bending vibration absorption peaks and Fe-O stretching vibration peaks,with more of the latter appearing Characteristic peaks ofγ-OH andσ-OH deformation zones.Compared with Fe₃O₄-2 catalyst,Fe₃O₄-1 catalyst has stronger magnetism and is more conducive to recovery.（3）Comparative analysis of the degradation effects of different systems of Fe₃O₄-1（or Fe₃O₄-2）,PS,Fe,Fe/PS,Fe₃O₄-1/PS（or Fe₃O₄-2/PS）on ciprofloxacin hydrochloride showed that the degradation effect of Fe₃O₄-1/PS（or Fe₃O₄-2/PS）system on CIP was significantly higher than that of Fe₃O₄-1（or Fe₃O₄-2）,PS,Fe,and Fe/PS system,indicating that the prepared iron oxide had better activation performance for persulfate.The single factor experimental method was used to investigate the effects of CIP concentration,catalyst dosage,persulfate dosage,and initial p H value on CIP removal.The results showed that for the Fe₃O₄-1/PS system,under the conditions of Fe₃O₄-1 dosage of 2.0 g/L,persulfate dosage of1.0 g/L,CIP concentration of 40 mg/L,and p H=3,the degradation rate of CIP reached its maximum value,reaching 93.34%.For the Fe₃O₄-2/PS system,under the conditions of Fe₃O₄-2 dosage of 0.2 g/L,persulfate dosage of 0.2 g/L,CIP concentration of 40 mg/L,and p H=3,the reaction system achieved the maximum degradation rate of CIP,which was 85.28%.The response surface analysis method was used to optimize three factors:catalyst dosage,PS dosage,and p H value,and the optimal reaction conditions were obtained.Under these conditions,the predicted CIP degradation rate was close to the experimental value.The cycling experiment results show that Fe₃O₄-1 still has a CIP degradation rate of over 72%after three cycling experiments,and Fe₃O₄-2 has a CIP degradation rate of over 65%after two cycling experiments.The former has better cycling utilization.The reaction mechanism was studied through quenching experiments,and the results showed that the main reactive oxygen species in the Fe₃O₄-1/PS system were SO₄^-·and ¹O₂,while the dominant reactive oxygen species in the Fe₃O₄-2/PS system were ¹O₂and·OH.The degradation intermediate products of CIP were analyzed using LC-MS method.10intermediate products were detected in the Fe₃O₄-1/PS system,and 9 intermediate products were detected in the Fe₃O₄-2/PS system.The corresponding degradation pathways were derived.The acute toxicity of the solution before and after the reaction was measured through seed germination and root elongation experiments.The results showed that in the reaction systems activated by two catalysts,the acute toxicity of CIP gradually decreased with the progress of the reaction,and the reduction ability of the Fe₃O₄-1/PS system on the acute toxicity of CIP was higher than that of the Fe₃O₄-2/PS system.By comparing and analyzing two types of iron oxide catalysts,it was found that the activation effect of Fe₃O₄-1 catalyst for persulfate degradation of CIP and its ability to reduce acute toxicity of CIP were significantly better than Fe₃O₄-2.Moreover,Fe₃O₄-1 catalyst had stronger magnetic properties and better recycling performance.Therefore,the research results of this paper indicate that the Fe₃O₄-1 catalyst prepared under alkaline conditions has better application prospects in the treatment of ciprofloxacin wastewater.