Hydrothermal Synthesis And Photocatalytic Modification Of Bi₂WO₆

Photocatalytic technology has the characteristics of being able to effectively use solar energy to degrade and recover wastewater.In recent years,it has been widely used in wastewater treatment.In the application and development of efficient photocatalytic technology,the development and progress of photocatalyst is the key to determine whether photocatalytic technology can be widely used.However,the photocatalyst in the current practical application process has the problems of low solar energy utilization,difficult recovery and high cost.Therefore,the development of a new type of photocatalyst with high photocatalytic performance is an inevitable trend in the development of photocatalytic technology.Bismuth tungstate?Bi₂WO₆?is an Aurivillius-type oxide,which is one of the semiconductor catalysts with the best visible light catalytic activity at present.Interlayer can be used as receptor to receive photogenerated electrons,which makes it have better solar energy utilization ratio,better stability and higher visible light catalytic activity than monolayer photocatalyst,and the preparation process is simple.The production cost is low,and it has been widely concerned in the field of new materials and photocatalysis in recent years.In this paper,Bi₂WO₆ was synthesized by a new tungsten source combined with simple hydrothermal method.The Bi₂WO₆ material was modified and the composite photocatalytic material with high activity was synthesized in order to apply it to the purification of water environment.The main research work and analysis showed that:?1?Bi₂WO₆ photocatalytic material was synthesized by hydrothermal method at 220?for 24h using tungstic acid as tungsten source.g-C₃N₄/Bi₂WO₆ composite photocatalysts were prepared by a simple refluxing method using g-C₃N₄ as the base material.The prepared Bi₂WO₆ had high crystallinity and purity,and could be used to photocatalyticdegradation of methylene blue solution under visible light irradiation.The experiments results showed that when the mass ratio of g-C₃N₄:Bi₂WO₆ was 4:100,it was the best preparation condition for the composite photocatalytic material.The energy levels of g-C₃N₄ and Bi₂WO₆ were matched,and photo-generated e^-/h⁺pairs could be effectively separated,thus enhancing the photocatalytic activity of g-C₃N₄/Bi₂WO₆ composite material.?2?Bi₂MoO₆/Bi₂WO₆ composite photocatalys had been synthesized by a simple refluxing method under mild conditions.When the molar ratio of Mo:W was 2:10,the photocatalytic activity of the Bi₂MoO₆/Bi₂WO₆ composite photocatalyst was the best,and the degradation efficiency was twice that of the single Bi₂WO₆.The Bi₂WO₆ matched with the energy levels of the Bi₂MoO₆ could effectively promote the separation of photo-generated electron-hole pairs,thus improving the photocatalytic activity of the composite photocatalyst.?3?In this paper,the Bi₂WO₆ and its modified composite photocatalyst prepared were applied to the treatment of phenols in metallurgical coking wastewater under visible light irradiation.At room temperature,when the concentration of phenol-containing wastewater was 10mg·L^-1 and the catalyst dosage was 0.05 g,the degradation rates of phenolic substances corresponding to Bi₂WO₆,g-C₃N₄/Bi₂WO₆ and Bi₂MoO₆/Bi₂WO₆composite photocatalyst were 14.6%,17.1%and 15.2%after 3h visible light irradiation,respectively.The result showed that the modified composite photocatalyst was more active in the degradation of phenol-containing wastewater than the Bi₂WO₆ photocatalyst.