| Photocatalytic oxidation technique is a simple and effective route towards removing toxicorganics from industrial wastewater,which has great potential in the prospect of sustainable development and application.However,photocatalytic oxidation technology has poor quantum efficiency,low visible-light utilization and difficulty in recycling etc.,which severely restricts its practical application in the treatment of actual wastewater.Given these research gaps,it is urgent and imperative to develop a new-type photocatalyst with advanced activity,effective visible-light-responsive,as well as good recycling performance for reuse in the field of water treatment at home and abroad.In recent years,the application of magnetic nanoscale photocatalyst in water treatmenttechnology has drawn widespread concern due to the enhanced physical,chemical properties and practicability of these materials.Owing to the introduction of magnetic materials into the nanocomposites,their separation can be easily completed through the employ of external magnetic fields,hence obtaining an economic,more efficient and environmentally friendly water purification process.Fe3O4 possess superparamagnetic,excellent conductivity as well as low cost of preparation;molybdenum-based oxide have visible light photocatalytic performance;graphene has been recognized as a excellent carrier for preparing composite photocatalyst in virtue of its large surface area,unique electronic properties,high optical transparency and outstanding adsorption performance.Efficient and environmentally-benign Mo S2@Fe3O4 and MoS2-Fe3O4-RGO photocatalyst were prepared by hydrothermal method,ultrasonic assisted route and in-situ synthesis approach.The micromorphology,crystallinity,chemical structure,physical adsorption properties,optical properties,and band structure of the as-synthesized nanocomposites were well characterized by various spectroscopic and microscopic techniques,including field emission scanning electron microscope?FE-SEM?,high resolution transmission electron microscopy?HRTEM?,X-ray powder diffraction?XRD?,energy dispersive X-ray spectrometer?EDS?,X-ray photo-electron spectroscopy?XPS?,N2 adsorption-desorption isotherm,ultraviolet-visible diffuse reflectance spectroscopy?DRS?,fluorescence spectrophotometer?PL?,Fourier transform infrared spectroscopy?FT-IR?and vibrating sample magnetometer?VSM?,and Raman spectroscopy.The photocatalytic activity of as-prepared magnetic composite photocatalyst were evaluated by the degradation of rhodamine B?RhB?,methylene blue?MB?or p-nitrophenol?4-NP?under visible-light irradiation.This study provides a theoretical basis for the future study of Mo-based magnetic photocatalysts and its application in the treatment of organic wastewater.The main contents and conclusions are as follows:?1?Study on the preparation,characterization and photocatalytic properties of petaloidMo S2@Fe3O4 photocatalyst:Novel magnetically recyclable MoS2@Fe3O4 nanocomposite with remarkable photocatalytic capability was prepared by virtue of a rational hydrothermal route.The results show that as-prepared samples have good structural,compositional,optical and magnetic properties.Photocatalytic activity was evaluated by degrading rhodamine B?RhB?and methylene blue?MB?aqueous solution under visible-light irradiation.In comparison with pure MoS2,the MoS2@Fe3O4 with 17 wt%dosage of Fe3O4?MF-17?possessed superior photocatalytic performance.The photocatalytic degradation showed an evident dependence on the initial pH value with respect to the RhB and MB solutions,where the optimal degradation efficiency was obtained at pH 3.0 and 11.0,respectively.More importantly,magnetic Mo S2@Fe3O4 hybrid can be well separated and easily recycled by an external magnetic field,still maintaining advanced activity after eight photoreaction cycles.?2?Study on the preparation,characterization and photocatalytic properties of ternary magneticMo S2-Fe3O4-RGO photocatalyst:Petaloid MoS2@Fe3O4 photocatalyst and magnetic MoS2-Fe3O4-RGO composite photocatalyst were synthesised by hydrothermal method.The photocatalytic activities of both were evaluated by degradation of RhB,MB and 4-NP simulated wastewater.The results indicate that loading graphene can effectively inhibit the combination of photogenic electron and hole,rusulting in the enhancement of the quantum efficiency and electron transfer ability of catalyst.When the amount of RGO loading is 5 wt%?MFG-5?,the obtained MFG-5 photpcatalyst possess the highest activity of photocatalyst;the degradation of RhB rate is as high as 99%,32%higher than that of MoS2@Fe3O4.The improved photocatalytic activity of MoS2-Fe3O4-RGO photocatalyst were closely related to the defect growth and the increase of the surface area,whilst also associated with the advanced electron transfer ability. |
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