Preparation Of Fluorinated And Indium Zinc Sulfide Modified Titanium Dioxide And Their Degradation On Rhodamine B

Environmental problems and energy crisis have pushed photocatalytic wastewater treatment technology to the forefront of scientific research.Titanium dioxide is regarded as the most commercially promising photocatalyst with high stability,easy availability and low toxicity.However,the high carriers recombination rate and wide band gap constrains its wide application in the field of wastewater.So there is an urgent need to find effective means to overcome these deficiencies.Nonmetallic modification is considered as a cost-effective modification method to accelerate carriers separation and migration.In addition,zinc indium sulfide possesses visible light absorption and high specific surface area,so its compounding with titanium dioxide is expected to expand the light absorption range of the catalyst and improve the photodegradation ability of the catalyst.Therefore,in this work,titania-based photocatalysts with excellent removal ability against rhodamine B in printing and dyeing wastewater were synthesized by surface fluorination and zinc indium sulfide modification,respectively.The study and conclusions are as follows:(1)Fluorinated titanium dioxide photocatalysts were obtained by one-step hydrothermal method using hydrofluoric acid as the fluorine precursor and proposed to inhibit the production of titanium difluoride oxide at high hydrofluoric acid concentration by introducing triethylamine.The optimum preparation parameters of the catalyst were determined by comparing the removal rate of rhodamine B as hydrothermal temperature 180 °C,hydrothermal time 12 h,HF : TBOT=1.5 : 1,TEA : TBOT=0.5 : 1(molar ratio).(2)Photocatalytic degradation of rhodamine B in printing and dyeing wastewater was carried out using fluorinated titanium dioxide,and the degradation rate of the prepared catalyst was 37 times higher than pure titanium dioxide.Further characterizations revealed that the fluorination modification and the inhibition of titanium difluoride production led to a decrease in the carriers recombination rate and an increase in the production of free hydroxyl radicals for titanium dioxide,which jointly resulted in a significantly higher photodegradation capacity.(3)The z-scheme heterojunction of indium zinc sulfide-modified titanium dioxide with visible light absorption ability was prepared in situ on titanium mesh using two-step hydrothermal method.The optimal conditions for the preparation of the catalyst were: hydrothermal temperature of 160 ℃,hydrothermal time of 6 h and indium zinc sulfide concentration of 10 m M.(4)The photodegradation experiments showed that the composite had the strongest photodegradation capacity,removing 95.8% of rhodamine B within30 min.The degradation of rhodamine B by the composite catalyst was controlled by the superoxide radical,hole and hydroxyl radicals together.The mechanism of rhodamine B degradation by the catalyst was investigated,and it was found that the broad light absorption range,fast carrier separation rate and strong redox ability of the prepared catalysts led to their efficient photodegradation.