Preparation And Performance Of TiO₂Photocatalyst And TiO₂/ZnO Composite Photocatalyst

TiO₂is an important photocatalyst, with the advantages of stable chemical properties,low-cost, non-toxic，and so on. It is widely applicated in the fields of organic pollutantsdegradation, disinfection sterilization and self-cleaning. In this paper, preparation methodsand process conditions of TiO₂and ZnO catalysts and TiO₂/ZnO composite photocatalystswere studied. The physical properties of these photocatalysts were characterized by themeans of SEM, XRD, TG-DTA, low temperature N₂adsorption, et al. Meanwhile, thephotocatalytic properties of samples were envaluated by degradation of methyl orangeaqueous solution. The research results are shown as follows:TiO₂photocatalyst can be prepared by sol-gel method, solvothermal andsol-solvothermal. Comparing the three ways, TiO₂particles prepared by thesol-solvothermal are more uniform, smaller particle size, larger specific surface areas andpore volume, and they have better thermal stability and photocatalytic degradation of themethyl orange solution. The proper preparation conditions of TiO₂photocatalyst bysol-solvothermal method are as follows: acid dosage is1mL, water dosage is1g,crystallization time is12h, and crystallization temperature is120°C. When the reactiontime is180min, the degradation rate of methyl orange solution could be up to95%The ZnO crystals were prepared by precipitation method, zinc acetate as the zincsource. ZnO crystals have complete polymorph, high crystallinity, small particle size,large surface areas and good thermal stability. The proper preparation conditions of ZnOphotocatalyst are as follows: CTAB concentration is0.05mol/L, aging time is4h,calcination temperature is450°C, and roasting time is2.5h. When the reaction time is180min, the degradation rate of methyl orange solution could be more than85%.TiO₂/ZnO composite photocatalysts were prepared by sol-gel method, butyl titanateand zinc acetate as main raw materials. The crystals of the composite photocatalysts areshown as layered distribution and agglomeration, particle size is less than500nm. Thesamples have both TiO₂and ZnO crystal styles and higher content of anatase. In addition,the isothermal N₂adsorption-desorption curves are conformed the â…£ adsorption curves,with obvious hysteresis loop. TiO₂/ZnO crystals have small particle size, large surface areas and pore volume, and high thermal stability. The proper preparation conditions ofTiO₂/ZnO composite photocatalysts are determined as follows: Zn: Ti molar ratio is0.25:1,HCl amount is0.15mL, calcination temperature is500℃, roasting time is2h. Afterprepared under the conditions, TiO₂/ZnO composite photocatalysts have high catalyticperformance.