Sulfur Doping Of Titanium Dioxide And Its Loading On Xonotlite

In recent years,with the continuous expansion of industrial scale,environmental pollution and energy shortage have became a major problem for human beings.Titanium dioxide is considered as an ideal semiconductor photocatalyst originating from its advantages of low cost,non-toxic,structural stability and high photocatalytic activity.Owing to its wide band gap,TiO₂ can only utilize UV-light during the photodegradation reaction,resulting in low utilization of sunlight.In addition,it is difficult to recover and reuse for high-activity catalysts with nanoscale,which may cause secondary pollution.In view of the above issues,we improved the visible light utilization and practicality of TiO₂ by modification of doping and loading.Herein,we synthesized TiO₂ nanoparticals through a hydrothermal method using titanium sulfate as the titanium source.Meanwhile,the influence of hydrothermal time and hydrothermal pH on the properties of TiO₂ was discussed and its optimum conditions were optimized.In order to improve the visible light utilization,we use thiourea as sulfur source to modify TiO₂.The structure,composition,morphology and photocatalytic activity of TiO₂ were characterized by XPS,FT-IR,XRD,TEM,UV-vis,nitrogen adsorption/desorption analysis and photocatalytic test.The experimental results showed that the photocatalytic activity of TiO₂ was best when the hydrothermal reaction time was 12 h and the hydrothermal reaction pH was 5.In addition,sulfur doping makes TiO₂ particles smaller in size,improved in stability,larger in pore size,wider in photoresponse range,enhanced in photodegradation and improved in cycle stability.The optimal S:Ti mole ratio is 1:3,in which the S-doping TiO₂ has the best photodegradation ability and can maintain a good photocatalytic activity over a wide pH range.In the aspect of titanium oxide loading,we synthesized TiO₂/xonotlite composite catalyst through the above optimal TiO₂ hydrothermal conditions by dynamic hydrothermal method using xonotlite fibers as isotopic carrier.The influence of TiO₂ load,calcination temperature,hydrothermal reaction pH and acid treatment were discussed.We can draw the following conclusions from the experimental results,in the hydrothermal process,the addition of TiO₂ would destroy the structure of xonotlite.Different TiO₂ loading ratios have large differences in morphology,pore structure distribution and especially in specific surface area of the sample.Furthermore,choosing suitable calcining temperature can improve the crystallinity of TiO₂ in the composite catalyst and improve the photodegradation ability of the sample.Composite catalyst synthesized under neutral hydrothermal conditions showed almost no photoactivity.However,the degradation performance increased by more than 30%after acid treatment.