Preparation Of Novel Tungsten-based Catalyst And Its Sterilization Mechanism

Water is indispensable for human beings.With the development of human society,people have realized the importance of drinking water safety.Pathogenic bacterial contaminated water without sterilization may cause diseases,such as typhoid fever,cholera which causes life safety concerns.Therefore,the development of drinking water disinfection technology is essential to ensure public health.However,traditional sterilization technologies,such as heat sterilization,ozone sterilization,ultraviolet sterilization and chlorine sterilization have disadvantages.For instance,they may cause high energy consumption,produce disinfection by-products and bacteria regrowth.It will further cause environmental problems,which is not in favor to sustainable development of human society.Therefore,it is urgent to develop a green,efficient,energy-saving and environmental friendly water disinfection technology.Photocatalytic disinfection technology has received more and more attention due to its use of solar energy as energy source.However,Ti O₂,the most widely used photocatalysts is only active under UV irradiation,which results in the limited application.The development of a photocatalyst with visible light response to improve photocatalytic sterilization efficiency could have significance for practical application.In this paper,E.coli K-12 was used as the model bacteria to evaluate the photocatalytic disinfection activity.A new tungsten-based catalyst(WO_3-x)has been synthesized to improve the disinfection efficiency,and a series of technology were employed to study its mechanisms of enhanced bacterial inactivation efficiency.In addition,the layered ultra-thin WSe₂was used as co-catalyst to improve the separation efficiency of photogenerated carriers and improve the activity of photocatalytic hydrogen peroxide production.An in-situ Fenton system was built by adding Fe（Ⅱ）to activate the produced hydrogen peroxide.The main contents are as follows:（1）In order to study the role of oxygen vacancies in the photocatalytic bacteria inactivation.Taking WO₃as an example,a microwave-assisted solvothermal method was used to quickly synthesize WO_3-xnanosheets.The bacterial inactivation efficiency is greatly improved compared to pristine WO₃.A series of technology were used to explore the internal mechanisms of enhanced photocatalytic inactivation efficiency.It was found that oxygen vacancies formed on WO_3-xcan improve the visible light absorption and the separation efficiency of photo-generated e^--h⁺pairs.（2）The ultra-thin layered WSe₂nanosheets were loaded on g-C₃N₄surface by solvothermal method.Compared with pristine g-C₃N₄,the hydrogen peroxide production performance under visible light by WSe₂/g-C₃N₄is significantly improved.The hydrogen peroxide concentration reached 81μmol/L without electron donors within 2 hours,which is11.2 times higher than that of g-C₃N₄.However,the inactivation efficiency by g-C₃N₄and WSe₂/g-C₃N₄composite has no obvious difference.In order to enhance the inactivation efficiency,an in-situ Fenton system was built to produce by adding Fe（Ⅱ）to generate more·OH,which greatly improved the bacterial inactivation efficiency.