Study On The Efficiency Of Removing Sulfonamide Antibiotics From Wastewater By Three-dimensional Electro-Fenton Activation Of Peracetic Aci

Sulfadiazines（SDZ）are one of the most commonly used sulfonamide antibiotic drug in human and animal medicine.As a result of the parent compounds and metabolites are not fully utilized by the organisms,a large amount of SDZ is widely distributed in the water environment.Green,rapid and efficient degradation of SDZ pollutants in the water environment has become a hot topic in water treatment.In recent years,three-dimensional electro-Fenton（3D-EF）technology on the existence of zero-valent iron（Fe⁰）has been widely studied due to its advantages such as high efficiency and non-selectivity.Due to the easy oxidation and agglomeration of Fe⁰,the activity of the system is reduced.Fe⁰ can be fixed by carrier load to reduce its adverse effects and improve the treatment effect of the system.Peracetic acid（PAA）as a strong oxidant with non-toxicity and low p H dependence.It can be activated by iron ions to produce a variety of free radicals to efficiently degrade refractory organic pollutants in water.However,there are fewer reports on the mechanism of SDZ removal by synergistic activation of PAA with 3D-EF and iron ions.In this study,based on the rapid and efficient removal of SDZ in water environment,a 3D-EF activation PAA system（3D-EF-PAA）was constructed.The performance of SDZ degradation was investigated,the optimal reaction parameters of the system were determined,and the particle electrodes in the system were optimized.The active species in the system were analyzed,and the mechanism and pathway of SDZ degradation were speculated.The specific research contents are as follows:（1）Study on the removal efficiency of SDZ by 3D-EF-PAA system.In the 3D-EF-PAA system with Fe⁰ as particle electrode,PAA showed excellent activation efficiency,which could quickly and efficiently degrade SDZ and broaden the p H application window of the system.The optimum reaction parameters in the system were determined:initial p H was 7,current density was 2 m A/cm²,Fe⁰ dosage was 0.5 g/L,PAA concentration was 0.2 mmol/L,electrolyte Na₂SO₄ concentration was 40 mmol/L.The introduction of Cl^-can accelerate the removal of SDZ,but the presence of NO₃^-,HCO₃^-and humic acid（HA）will inhibit the efficiency of SDZ degradation.（2）Experimental study on optimization and stability of system particle electrode.The particle electrode of activated carbon loaded with Fe⁰（AC/Fe⁰）was prepared and its effect on the activation of PAA in 3D-EF-PAA system was optimized.The results showed that SDZ could be completely degraded under the conditions of AC/Fe⁰ dosage of 0.14 g/L,initial p H of7,current density of 2 m A/cm²,PAA concentration of 0.3 mmol/L and electrolyte Na₂SO₄concentration of 20 mmol/L.The results of coexisting ions showed that low concentrations of Cl^-,NO₃^-,HCO₃^-and HA inhibited the degradation of SDZ.The 3D-EF-PAA system has lower energy consumption than the control system,which confirms that the 3D-EF-PAA system has a good development prospect.（3）Mechanism analysis of SDZ degradation in 3D-EF-PAA system.The 3D-EF-PAA system can accelerate the circulation of iron ions,enhance the efficiency of PAA activation,and enhance the degradation effect of the system on SDZ.The kinetic results showed that the degradation process of SDZ in 3D-EF-PAA system was more in line with the pseudo-second-order reaction kinetic model.The main active species of the 3D-EF-PAA system was determined to be hydroxyl radicals（·OH）by free radical quenching experiments and electron paramagnetic resonance spectrometer（EPR）.The degradation products of SDZ were identified by high-performance liquid chromatography with tandem mass spectrometry（HPLC-MS/MS）,and it was speculated that SDZ may have three degradation pathways.