Preparation And Performance Study Of TiO₂-based Photocatalytic Coating

With the accelerating process of industrialization in our country,the problem of water pollution caused by industrial discharge of wastewater has become more and more serious.Among them,the printing and dyeing industry is the major discharger of industrial wastewater.Printing and dyeing wastewater has many characteristics such as high emissions,deep chromaticity,high levels of organic pollutants,complex water quality,and high toxicity.It has caused great harm to the surrounding environment and the human body.Therefore,the control and treatment of printing and dyeing wastewater is imminent.Photocatalysis has been widely used as a new high-tech energy-saving modern green environmental protection technology,which titanium dioxide(TiO2)is the most widely used.In this project,methyl orange was used as simulated contaminants in printing and dyeing wastewater.The titanium dioxide materials were doped with Si and RGO by hydrothermal synthesis to improve the photocatalytic performance of titanium dioxide materials.TiO2 particles were prepared by screen printed and thermally sprayed as a coating fixed on the substrate,TiO2 coating can achieve recycling,but also have good photocatalytic properties.In this paper,the different dosages of Si-TiO2 powder and TiO2/RGO composite powder were prepared by hydrothermal synthesis method,which improved the photocatalytic activity of TiO2 effectively.Si-TiO2 powder has good photocatalytic activity under ultraviolet light.The photocatalytic performance of 20%Si-TiO2 powder is best,and the degradation rate of methyl orange can reach more than 98%.The TiO2/RGO composite powders have good photocatalytic performance under UV and visible light conditions,and the TiO2/RGO(30mL)composite powders have the best performance.With the increase of the amount of GO,the photocatalytic performance decreased significantly.Secondly,Ti02-based coatings were prepared by screen printing process,and the effects of different printing layers and heat treatment temperatures on the microstructure and photocatalytic properties of the coatings were investigated.The TiO2 coating with 4 layers of printing layers and a heat treatment temperature of 700? has the best comprehensive performance,and the coating can be catalyzed in 10 cycles.The degradation rate can still reach 92%.The cyclic experiment proves that the coating has better performance and good cycle stability.At the same time,the hydrothermally synthesized powder was prepared as a coating according to the above process parameters,and the coating prepared with TiO2/RGO composite powder had the best photocatalytic performance.Finally,a TiO2-based coating was prepared by plasma spraying process to study the effect of hydrogen flow rate and different Si doping amount on the microstructure and photocatalytic performance of the coating.The increase of H2 flow rate will promote the grain growth of Ti02.Most of the crystalline phase of Ti02 coating exists in the rutile phase.When the flow rate of H2 is 8 L/min,the photocatalytic performance of TiO2 coating is better than that of H2 flow 4 and 10 L/min The introduction of Si can inhibit the grain growth of TiO2.At the same time,the content of anatase phase in TiO2 coating increases significantly.Si doping can make Ti-O-Si bond appear in TiO2 coating.With other parameters unchanged,the Si-doped TiO2 coating had better photocatalytic properties than the pure TiO2 coating.