The Efficient Degradation Of Typical Fluoroquinolone Antibiotics In Water By Two Magnetic Nanocomposites

Fluoroquinolones antibiotics?FQs?are widely used in the prevention and treatment of bacterial infections.In recent years,these antibiotics have often been detected in water and even the presence of trace amounts can pose a potential threat to humans and the entire ecosystem.In recent years,advanced oxidation technology has a broad application prospect because of its strong oxidation capacity,wide application range,high-efficiency treatment of most refractory organic pollutants and low treatment cost.Based on this,Ag₃PO₄/Bi₂₅FeO₄₀/GO and CuS/Fe₂O₃/Mn₂O₃nanocomposites were prepared in the study.And the treatment of typical fluoroquinolones antibiotics in water was carried out by photocatalytic advanced oxidation and activated peroxymonosulfate?PMS?advanced oxidation respectively.Besides,petrochemical industry wastewater is one of the industrial wastewater which is difficult to be treated because of its large discharge and complex composition.There are still many refractory organics in the secondary effluent of petrochemical wastewater after biological treatment.In order to meet the discharge or reuse standards,it is necessary to carry out advanced treatment.However,the commonly used deep treatments,such as ozone oxidation,ultraviolet disinfection,activated carbon adsorption etc.,had the disadvantage of high operating cost.Therefore,in this paper,two kinds of magnetic nanocomposites were used to treat the secondary effluent,and the treatment effects of the two methods were compared.The main works of this paper are as follows:In order to improve the photocatalytic activity and stability of the single-phase catalyst,Bi₂₅FeO₄₀/GO nanocomposite was prepared by hydrothermal method,and the preparation parameters were optimized.It was found that the binary composite catalyst with a mass ratio of 7:3 had the best catalytic performance.The binary composite catalyst with this proportion was selected,and the Ag₃PO₄/Bi₂₅FeO₄₀/GO ternary nanocomposite was fabricated by the co-precipitation method.Its physical and chemical properties,light absorption properties,photoelectrochemical properties,and photocatalytic properties were analyzed by various characterizations.The photocatalytic performance of Ag₃PO₄/Bi₂₅FeO₄₀/GO was evaluated by degrading lomefloxacin?LVF?,and the reaction conditions were optimized.The results showed that when the dosage of catalyst was 0.4 g/L and the solution initial pH was 3,the degradation efficiency of Lomefloxacin was the highest.After 120 minutes of irridation,it could reach 86.5%.Electrochemical test results show that Ag₃PO₄/Bi₂₅FeO₄₀/GO nanocomposite has higher transient photocurrent intensity(1.04?A·cm^-2),smaller charge transport resistance,and higher carrier concentration compared with Bi₂₅FeO₄₀/GO.At the same time,according to the scavenging experiment,·O₂^-,h⁺,e^-,H₂O₂ and·OH were identified as reactive species in the system,and·O₂^-and e^-played a major role.In addition,the effects of the coexistence of inorganic anions and humic acid in the solution on the reaction system were explored.The results showed that inorganic anions have different effects on the degradation reaction with different concentrations,but all have inhibitory effects.Based on the research results,a mechanism of enhanced photocatalytic performance of Ag₃PO₄/Bi₂₅FeO₄₀/GO nanocomposite was proposed.Furthermore,the CuS/Fe₂O₃/Mn₂O₃ nanocomposite was prepared to activate peroxymonosulfate.Firstly,Fe₂O₃/Mn₂O₃ binary nanocomposite was synthesized by high temperature calcination method,and then CuS/Fe₂O₃/Mn₂O₃ ternary nanocomposite was prepared by precipitation method.The results showed that when the ratio between CuS and Fe₂O₃/Mn₂O₃ was 1:1,the catalytic effect was better than that of CuS,Fe₂O₃/Mn₂O₃ and other ternary composite.At the same time,the physicochemical properties of CuS/Fe₂O₃/Mn₂O₃ were analyzed by various characterizations.The catalytic performance of CuS/Fe₂O₃/Mn₂O₃was evaluated by the degradation of ciprofloxacin?CIP?by activated PMS.When the dosage of catalyst is 0.6 g/L,the dosage of PMS is 0.6 g/L,the solution initial pH was 5.84,the catalytic performance was the best,and it reached 88%after 120 min reaction.The reaction followed Langmuir's first-order kinetic equation,and the reaction rate constant is 0.1min^-1.In addition,the effects of inorganic anions and humic acid on the reaction were also studied.Through the scavenging experiment and electron paramagnetic resonance?EPR?,it was found that the reactive species in the system were·OH and SO₄^·-,and the·OH played a major role in the reaction.Through the detection of ciprofloxacin degradation intermediates,the possible degradation pathways were inferred.The catalytic mechanism of CuS/Fe₂O₃/Mn₂O₃ activating PMS to degrade pollutants was proposed.In addition,CuS/Fe₂O₃/Mn₂O₃ has good magnetism,which provides the possibility of recycling.In order to further expand the application of the two magnetic catalysts,the secondary effluent of petrochemical wastewater was treated by them.In addition,the amount of catalyst,PMS and pH were optimized,and the best reaction conditions were explored.The results showed that when the optimal dosage of Ag₃PO₄/Bi₂₅FeO₄₀/GO was 2.0 g/L,the removal rate of COD_Cr was 72.9%after 120min reaction.When the optimal catalyst dosage and PMS dosage of CuS/Fe₂O₃/Mn₂O₃were 1.0 g/L,the removal rate of COD_Cr was 73.8%after 60 min reaction.Finally,the result indicated that the treatment of secondary effluent via CuS/Fe₂O₃/Mn₂O₃activating PMS was better.