The Research Of Fe₃O₄@MoS₂ Quantum Dots Light Assisted Fenton Technology For Treatment Of Tetracycline Wastewater

In recent years,the influence of antibiotics represented by tetracycline on the environment has attracted much attention,and the removal of tetracycline antibiotics in the environment has become one of the important environmental problems.In this paper,the polyhedral Fe₃O₄?Fe₃O₄ for short if not specified?and Fe₃O₄@MoS₂quantum dots?represented by Fe₃O₄@MoS₂ QDs?were successfully prepared by hydrothermal method in order to effectively degrade high-concentration tetracycline organic wastewater.On this basis,a variety of advanced oxidation technologies were used in combination to establish two photocatalytic oxidation systems,namely,Fenton catalyzed oxidation assisted by UV and Fenton catalyzed oxidation assisted by visible light catalyzed oxidation.Both systems can effectively treat tetracycline organic wastewater.XRD,XPS,SEM,TEM,VSM and ac impedance were used to characterize the composition,morphology,structure,magnetism and electrochemical properties of Fe₃O₄ samples.The exposed{110}high-energy crystal surface of the material has large proportion.And the material has small particle size and large specific surface area,which can be recovered and reused by external magnetic field,and has strong structure and chemical stability.Using this material as catalyst,the UV assisted Fenton catalytic oxidation system with tetracycline simulated wastewater as the target pollutant was established.At room temperature?20±1??,the optimal experimental conditions were:the initial tetracycline concentration was 50 mg/L,pH was 7.0,the dosage of H₂O₂ was 10 mmol/L,and the dosage of catalyst was 0.3g/L.The degradation rate of tetracycline was 97.5%after 90 min of reaction,and the mineralization rate was 56.5%after 120 min.The degradation efficiency of the catalyst remained about 91.7%after 5 cycles.Through ESR analysis,it was found that the oxidation system contained hydroxyl radical·OH and superoxide radical O2·^-.In order to broaden the activated spectral range of catalyst and improve the efficiency of natural light use,Fe₃O₄@MoS₂ QDs composite catalyst was synthesized by hydrothermal method based on Fe₃O₄.The composition,structure and morphology of the composite catalyst were analyzed by means of XRD,XPS,SEM and TEM.The particle size of the prepared sample Fe₃O₄ was smaller and more dispersed,and Fe₃O₄formed heterojunction with MoS₂.The photocatalytic activity of Fe₃O₄@MoS₂ QDs composite catalyst was investigated.After 60 min,the degradation rate of tetracycline was 98.6%and the mineralization rate was 65.8%.Under the same reaction conditions,the removal rate and mineralization of tetracycline in Fe₃O₄@MoS₂ QDs Fenton catalyzed oxidation assisted by visible light catalyzed oxidation was significantly higher than that in other systems,proving that the introduction of photocatalyst can improve the oxidation capacity of the system.To explore the oxidation mechanism of the system,ESR analysis and radical quenching experiments were carried out on the system.The results showed that both the catalytic oxidation system of ultraviolet assisted Fenton and Fenton system of Fe₃O₄@MoS₂ QDs visible-light catalytic synergistic system contained hydroxyl radical·OH and superoxide radical O2·-,but the reaction system was mainly dominated by·OH.The oxidation of photocavitation h+in Fe₃O₄@MoS₂ QDs vis-catalyzed synergistic Fenton system promoted the degradation of the system.