Preparation Of Nano-TiO₂ Coated On Porous Mineral-based Microporous Ceramics

Nano-TiO₂ is a kind of photocatalyst with high catalytic activity and stable chemical properties.However,powder of nano-TiO₂ is easy to reunite,it is difficult to separate from liquid and difficult to be recycled.In order to solve the problem,this paper focused on exploiting supported TiO₂.First of all,porous mineral-based micro-porous ceramics with high porosity,high strength and high adsorption performance were obtained,using diatomite-based porous mineral as main material.Then micro-porous ceramics supported TiO₂nanocomposites were obtained by sol-gel and impregnation method,using micro-porous ceramics with excellent properties as carrier.The photocatalyst properties of nano-TiO₂/micro-porous ceramics were evaluated with methylene blue as the model pollutant.The physical,adsorption and catalytic properties of micro-porous ceramics and nano-TiO₂/micro-porous ceramics were characterized the by hydrostatic balance,X-ray Diffractometer?XRD?and Ultraviolet-visible spectrophotometer?UV-vis?techniques.Adjusting the powder formula,particle size of powder and sintering temperature,micro-porous ceramics with excellent properties is obtained.It was found that the optimal sintering additives content and diatomite content are 10%and 40%,respectively.Besides,the optimal median particle size(d₅₀)of powder and sintering temperature are 5.165?m and 1000°C,respectively.The micro-porous ceramics retains the original pores of diatomite,that the particles bonded together,the distribution of pores was uniform,the porosity was 56.03%,and the compressive strength is 29.73 MPa.The micro-porous ceramics showed good adsorption performance.It was found when the usage of micro-porous ceramics is 2 g,the removal rate of 50 mL methylene blue is 91%at the concentration of 10 mg/L.The nano-TiO₂/micro-porous ceramics exhibited excellent photocatalytic properties.It was found that TiO₂ was coated on the micro-porous ceramic successfully and distributed uniformly;the carrier increased the transition temperature to 900°C from 700°C about anatase to rutile,the grain size of TiO₂ decreased greatly;the absorption threshold of TiO₂decreased,the band gap increased from 3.14 ev to 3.18 ev,resulting in stronger redox ability of electron-hole and higher photocatalytic activity of TiO₂.The removal experiment of methylene blue in ultraviolet light showed when the usage of micro-porous ceramics was 1 g,the removal rate of 50 mL methylene blue was 86%at the concentration of 10 mg/L;while the usage of nano-TiO₂/micro-porous ceramics was 1 g,the removal rate of 50 mL methylene blue was 100%at the concentration of 10 mg/L.So TiO₂was very important in photocatalytic degradation.When the nano-TiO2/micro-porous ceramics was used 6 times,the removal rate of methylene blue was all higher than 90%,nano-TiO₂/micro-porous ceramics showed high catalytic activity and stability.This study has experimental significance in preparation of coated nano-TiO₂ and dealing with organic wastewater.