Study On Electrochemically Activated Sulfite For Degrading Typical Antibiotics In Water

With the rapid development of social industrialization,water resources have been severely polluted.Antibiotics are emerging difficult to degrade organic pollutants.They have the harm of biological toxicity,induced antibacterial or anti-drug genes,and threatening drinking water safety.Its half-life in the water environment is difficult to effectively remove through traditional water treatment methods.Therefore,it is necessary to study a processing process of high-efficiency degradation antibiotic wastewater.Advanced Oxidation Processes（AOPs）has the advantages of wide applicable scope,strong oxidation activity,and not easy to generate secondary pollution,among which electrochemical oxidation（Electro）can effectively activate sulfite（S（IV））,the precursor of sulfate radicals(SO₄^·-),and produce strong oxidizing hydroxyl radicals（·OH）,SO₄^·-,superoxide anion(O₂^·-)and monocytometric oxygen（¹O₂）and other active substances to effectively degrade antibiotics in water.In this study,Electro and S（IV）were combined to form a synergistic system to treat antibiotic wastewater.The main research contents are as follows:（1）The Electro/S（IV）system was constructed,the removal efficiency and degradation mechanism of metronidazole（MTZ）were studied.The results showed that the removal rate of MTZ by the system within 20 min was 87.27%when the current was 10 m A,The S（IV）concentration was 8.0 m M,the initial p H was 5.0,the electrolyte concentration was 20 m M,and the MTZ concentration was 10 mg L^-1.The COD removal rate of the system to the actual wastewater was 82.4%.HCO₃^-and HA in natural water components partially inhibited the degradation of MTZ in the system,while NO₃^-and Cl^-had almost no effect.Free radical masking experiments prove the presence in the system.The four active substances of OH,SO₄^·-,O₂^·-and ¹O₂ jointly degrade MTZ.The intermediate products of the system degradation MTZ were identified by high performance liquid chromatography-mass spectrometry（HPLC-MS）,and the degradation path of MTZ was speculated.（2）Using calcium sulfite（Ca SO₃,Sulfite）as the source of SO₄^·-,an Electro/sulfite system was constructed,and its removal efficiency and degradation mechanism of tetracycline（TC）were studied.The results showed that the removal rate of TC by the system within 50 min was 75.08%when the current was 10 m A,the sulfite concentration was 8.0m M,the initial p H was 6.0,and the TC concentration was 10 mg L^-1,and the system could effectively degrade typical refractory organic pollutants in water such as MB,MO and MTZ.Cl^-,SO₄^2-and HA partially inhibited the degradation of MTZ in the system.Free radical masking experiments prove the presence in the system·OH,SO₄^·-,O₂^·-and ¹O₂ four active substances jointly degrade MTZ,of which·OH and ¹O₂ are the main oxidizing active substances.（3）Electro and ferric iron（Fe（III））synergistically activate S（IV）,and the Electro/S（IV）/Fe（III）system was constructed,and the removal efficiency and degradation mechanism of sulfamethoxazole（SMX）were studied.The results showed that the removal rate of TC within 60 min was 84.88%when the current was 10 m A,the S（IV）concentration was 2.0m M,The Fe（III）concentration was 0.2 m M,the initial p H was 6.0,the electrolyte concentration was 5 m M,and the SMX concentration was 40 mg.The removal rate of TC within 60 min was 84.88%,and the system could effectively decompose typical refractory organic pollutants in water.The COD removal rate of the system to the actual wastewater was 73.81%.The natural water components had no effect on the degradation of SMX by the system.Free radical masking experiments prove the presence in the system·OH,SO₄^·-,O₂^·-and ¹O₂ co-degrade SMX.The system can promote the effective circulation of Fe（Ⅱ）/Fe（Ⅲ）,enhance its activation of S（IV）and degradation of SMX.