Study On Preparation Condition Optimization And Photocatalytic Activites Modification Of Bismuth Tungstate

The fast growing society has two sides.It brings benefits to people as well as negative effects.At present,environmental pollution is one of the challenges that human beings need to deal with seriously.The random discharge of organic pollutants will have a greater impact on human clothing,food,housing,transportation and physical health.Now,the prevention and control measures are mainly taken from the two aspects of source control and pollution control.However,in terms of today’s social development,in addition to the need to strengthen control at the source,the main aspect to solve the problem is pollution control.Therefore,it is necessary to find efficient,green and environmental protection technology to treat organic pollutants.Photocatalytic technology is one of the most promising development directions for the degradation of environmental pollutants under normal temperature and pressure conditions.It is environmentally friendly during the entire operation process,no secondary pollution,and has many advantages such as green and sustainable.Among many photocatalyst materials,bismuth-based semiconductor materials have the most application prospects.In particular,the Bi₂WO₆perovskite-type oxide material with the simplest structure in the Aurvillius series is favored by researchers because of its abundant resource reserves,non-toxicity,suitable forbidden band width,and good structural stability.However,in practical applications,Bi₂WO₆ has many shortcomings such as rapid photo-generated charge recombination and low visible light utilization,which makes its photocatalytic activity low.Therefore,in order to solve this defect,it is of great significance to develop the photocatalytic activity of Bi₂WO₆ base materials.In this article,take Bi₂WO₆ as the research object,and strengthen the photocatalytic activity of the material by building a heterojunction with the semiconductor MIL-53（Fe）material to achieve the purpose of high-efficiency degradation of pollutants.In this paper,by optimizing the hydrothermal preparation conditions of Bi₂WO₆,the MIL-53（Fe）/Bi₂WO₆ composite photocatalysts with different mass ratios were prepared to degrade 20 mg/L rhodamine B（Rh B）and 20 mg/L phenol.The degradation rate in a certain period of time is used to measure the photocatalytic activity of the materials.Experiments found that when the reaction time and temperature for 12 h and180℃,the sample under visible light irradiation,respectively,after 80 min and 60 min,pure Bi₂WO₆ photocatalytic degradation of Rh B and phenol decoloring rate were 56.4%and 25.5%respectively,When the mass ratio of Mil-53（Fe）to Bi₂WO₆ was 5 wt%,the degradation rates of Rh B and phenol were as high as 96.4%and 59.2%,respectively,which were 3.8 times and 3.3 times higher than those of pure Bi₂WO₆.According to the data of decolorization rate,the addition of MIL-53（Fe）greatly improved the efficiency of Bi₂WO₆ in the visible light degradation of Rh B and phenol.Characterized by technical specification,introducing MIL-53（Fe）in Bi₂WO₆,MIL-53（Fe）as a support rod,Bi₂WO₆ nanoparticles uniform growth on the surface,causing Bi₂WO₆ become larger surface area,the forbidden band width becomes narrower,make its active site exposed more and electron transition easier.Thus accelerate the electron transfer rate,inhibit the light fast electrons and holes of composite,eventually to improve the photocatalytic activity of Bi₂WO₆ purpose.Furthermore,the analysis of free radical trapping experiments showed that the hole（h⁺）and superoxide radical（·O₂^-）were the main active groups in the photocatalytic degradation process.It is worth noting that the catalyst also has excellent structural stability and photocatalytic durability.