Study On The Preparation Of Mo-based Catalysts And Its Catalytic Performance For Simulated Dye Wastewater

The wet catalytic oxidation and photocatalytic oxidation technology have great potential in thetreatment of refractory wastewater.Especially the photocatalytic oxidation technology is a research hotspot.However,in process of practical wastewater treatment,there are still some problems which restrict the development of photocatalytic technology,such as,the electron hole pair can not be separated effectively,the repetition of the catalyst is inferior and the utilization rate of the natural solar light is poor.In this regard,it is of great significance to develop a variety of excellent and reproducible catalysts for the wastewater treatment in the world.In this study,MoO₃,MoS₂,BiVO₄/Bi₂S₃/MoS₂ and 3D MoS₂/RGO catalysts were prepared bysimple,green hydrothermal method,and the hydrothermal temperature,calcination temperature,pH,MoS₂and RGO loading were adjusted through the whole experiment.the crystal forms,physical adsorption properties,optical properties,microstructure,band structure,chemical structure and photochemical properties of the catalysts were measured by characterization of X-ray diffraction analysis?XRD?,transmission electron microscopy?TEM?,field emission scanning electron microscope?FESEM?,X-ray photoelectron spectroscopy?XPS?,UV-Vis diffuse reflectance spectroscopy?DRS?,Raman spectroscopy?Raman?,etc..The catalytic activity of the prepared catalysts was evaluated by the degradation of malachite green?MG?,rhodamine B?RhB?,methylene blue?MB?,crystal violet?CV?or gentian violet?GV?under indoor environment or the natural sunlight irradiation or simulated visible light.This study provides a theoretical basis for the subsequent development and treatment of Mo-based catalyst for the degradation of organic wastewater.The main contents and conclusions are as follow:?1?Study on the preparation,characterization and properties of MoO₃ catalyst:The MoO₃ catalystsas a wet air oxidation catalyst have been synthesized by a simple hydrothermal method.During the synthetic process,a detailed orthogonal design on the preparation conditions was performed,aiming to optimize the parameters to produce MoO₃ with the most prominent catalytic performance.The catalytic activities of the synthesized materials were evaluated via the decolorization of dye wastewater at room conditions.The effects of calcination temperature,catalyst dosage,and initial concentration of Rhodamine B?RhB?on the degradation efficiency were investigated,where it was found that the sample calcinated at 400°C exhibited superior catalytic performance.?2?pH-dictated synthesis of novel flower-like MoS₂ with augmented natural sunlightphotocatalytic activity:An efficient and facile hydrothermal route for the pH-dictated synthesis of flower-like MoS₂ photocatalyst was developed.Scanning and transmission electron microscopy characterization?SEM and TEM?show the detailed morphologies of MoS₂ microflowers.X-ray diffraction and photoelectron spectroscopy analysis?XRD?confirm that the as-obtained product is of hexagonal MoS₂ phase.The photocatalytic properties of flower-like MoS₂ were evaluated by the degradation of RhB and MB under natural sunlight irradiation.The synthetic pH value could dictate the MoS₂ performance,where MS-1?pH=1?exhibited the best response amongst all the samples.?3?Study on the preparation,characterization and properties of novel Bi VO₄/Bi₂S₃/MoS₂ n-pheterojunction:The novel three-component BiVO₄/Bi₂S₃/MoS₂ heterojunction was successfully fabricated through a facile in-situ hydrothermal method based on the formation of the intermediate Bi₂S₃ by coupling BiVO₄ and MoS₂ precursor.The Bi₂S₃ was easily formed attributing to the strong interaction between Bi³⁺and S^2-ions with the aid of the hydrothermal reaction.The photocatalytic performances of samples were systematically investigated via the photocatalytic degradation of RhB,MB and MG under solar light irradiation.As a result,the photocatalytic degradation rate of BM-10 for RhB,MB and MG are 97%,93%and 94%,respectively.The enhanced photocatalytic activities could be due to the suppression of charge recombination and the enhanced the visible light absorption of BiVO₄/Bi₂S₃/MoS₂ heterojunction.?4?Study on the preparation,characterization and properties of 3D MoS₂/RGO composite aerogelphotocatalyst:The activity of the photocatalyst was effectively enhanced by the successful doping of graphene to the prepared MoS₂/RGO photocatalyst using a simple hydrothermal method.The influence of the proportion of MoS₂ and RGO on the photocatalyst during the synthesis process was studied.The results show that,when the mass ratio of MoS₂ and RGO is 1:2,the prepared photocatalyst MG-4 has the optimal activity.After photocatalytic degradation,the degradation rate of RhB,MB,MG,GV and CV simulated wastewater can reach more than 90%.