| Photocatalytic oxidation technology is one of the effective technologies to remove organic pollutants from water.Nano molybdenum disulfide(MoS2)has become a research focus in the field of photocatalysis in recent years because of its narrow band gap and excellent absorbption for visible-light.However,the hydrophobic agglomeration and limited catalytic active sites of MoS2 brings great challenges to its application.In this paper,modified zeolite was used as carrier to soupport MoS2.The preparation conditions,performance regulation and environmental factors of zeolite based molybdenum sulfide(MoS2@Z)photocatalysts were studied in depth.The photocatalytic degradation mechanism and pollution degradation path of composite photocatalysts were systematically revealed.Through the preparation of simple catalyst products,the performance of composite photocatalysts for the degradation of tetracycline(TC)under actural sunlight irradiation was investigated.The effects of the type of sulfur precursor,the loading amount of molybdenum disulfide,the initial pH value of precursor and the hydrothermal reaction temperature on the TC degradation performance of MoS2@Z were studied.The optimized MoS2@Z-5 photocatalyst(MoS2 loading amount is 5 mmol)was able to achieve the degradation efficiency of 84.46%for TC.It was found that the hydrophilicity of MoS2@Z-5 increased by modified zeolite effectively solved the problem of hydrophobic agglomeration of nano-MoS2,and the local fault structure of nano-MoS2 with smaller size and more active sites was prepared by inhibiting the longitudinal growth of MoS2.The effect of environmental factors on the photocatalytic degradation of TC by MoS2@Z-5 was investigated.The results showed that the degradation efficiency of TC by MoS2@Z-5 reached 87.23%within 150 minutes at the initial pH of 6.Coexisting ions can inhibit the photocatalytic performance of MoS2@Z-5,and the cationic inhibition is greater than that of anion.UV diffuse reflectance spectra showed that the photoabsorption performance of MoS2@Z-5 decreased after the introduction of modified zeolite,and the high photocatalytic activity was mainly attributed to the increase in the number of active sites at MoS2@Z-5 edge,rapid electron migration rate,good separation efficiency of e-/h+ and suitable isoelectric point value.CoS2/MoS2@Z catalysts with different Co/Mo molar ratios were prepared.The degradation efficiency of TC by CoS2/MoS2@Z-5(Co:Mo molar ratio=5:5)was 96.75%.Strong adsorption,improvement of visible light absorption and efficient e-/h+separation efficiency are the main mechanisms for the improvement of the photocatalytic performance of MoS2@Z after the introduction of CoS2.The main active groups in the reaction system are hole(h+)and superoxide radical(·O2-).Tetracycline is degraded by deamination,dihydroxylation,deamination,ring opening reaction,carbonylation and so on.The full spectrum CeO2/MoS2@Z catalyst was successfully synthesized.It was found that CeO2/MoS2@Z-3(Ce:Mo molar ratio=3:7)had the best catalytic performance,and the degradation rate of TC was 98.32%.Moreover,the sharp edge of MoS2 in CeO2/MoS2@Z-3 was still exposed,which effectively avoided the degradation of catalytic performance caused by CeO2 masking of the active site at MoS2 edge.The main active species in the reaction system are ·O2-and h+,·O2mainly comes from the combination of the adsorbed oxygen of CeO2 and oxygen molecules in the system and e-.The degradation efficiency of CeO2/MoS2@Z-3 product on TC was 84.19%in 24 hours under natural light irradiation.The results of this study will provide a theoretical basis for the development and application of MoS2 and zeolite,and provide reference for the study of synergistic mechanism and property regulation between MoS2 and non-metallic materials. |
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