The Research On Preparation, Modification And Photocatalytic Performance Of Titanium Oxide Nanotubes

TiO2, one important photocatalyst, has many advantages, such as low cost,non-toxic as well as a high activity. In addition, TiO2nanotubes of tubular structurepossess unique physical and chemical properties including large specific surface area,good electron/proton conductivity and high adsorption capacity. In particular, its uniquestructure can make the photo-generated electron and hole escape to the nanotube surfaceparticipating in redox reactions in picoseconds, which reduced the recombinationprobability of electron and hole so as to improve photo quantum efficiency. Therefore,TiO2nanotubes are expected to improve the photoelectric conversion efficiency andphotocatalytic performance of TiO2. Meantime, the study on the TiO2nanotube will begreat potential significance.In this paper, the H2TiO3.nH2O nanotubes were prepared by hydrothermal methodusing TiO2as precursor, and then the as-prepared material was respectively usingcalcination and hydrothermal method to prepare TiO2nanotubes. Furthermore, modifiedTiO2nanotubes were prepared by doping nonmetal. In addition, the photocatalyticperformance of titanium oxide nanotubes were investigated using methyl orangeaqueous solution,KNO3aqueous solution as simulation wastewater. The main researchresults are as follows:1.The prepartion and modification of titanium oxide nanotubes material(1) TiO2nano powder were prepared by hydrothermal method using Tetrabutyltitanate as raw material and were characterized by XRD and SEM. The resultsdemonstrated that the TiO2nano powder is a kind of spherical granules about20nm andthe TiO2nano powder was consisted of77%anatase and23%rutile.(2) H2TiO3.nH2O nanotubes were prepared by hydrothermal method using the TiO2 nano powder that prepared by ourself as precursor. H2TiO3.nH2O nanotubes can betreated by calcination method and hydrothermal method and get TiO2nanotubes.Theproducst were characterized by XRD and SEM.The results demonstrated that theH2TiO3.nH2O nanotubes are amorphous structure and highly disorderedintertwined.Pipe diameter is about20nm, the length is about200nm.The TiO2nanotubes are anatase structure.(3) The modify TiO2nanotubes that dopeing Cl and S are prepared by two stepshydrothermal method and were characterized by FT-IR. The results demonstrated thatSO42-form chelate S modified TiO2nanotubes.2.Photocatalytic activity of titanium oxide nanotubes materia(1) Using high pressure sodium lamp as simulation of visible light,using methylorange aqueous solution as simulation wastewater test the photocatalytic activity ofphotocatalyst,the results demonstrated that:1The photocatalytic activity of H2TiO3.nH2O nanotubes is lower. Whenphotocatalytic reaction time is150min, its degradation rate is only24.7%.2Under the same conditions, the photocatalytic activity of TiO2nanotubes weresignificantly improved and the degradation rate of TiO2nanotubes prepared bycalcination method(400℃,2h) and hydrothermal method(120℃,6h) was50.0%and75.0%, respectively.3Under the same conditions,the photocatalytic acticity of modified TiO2nanotubes is excellent, the the degradation rates of of TiO2nanotubes that dope Cl and Sare98.0%and100%.(2) Using high pressure sodium lamp as simulation of visible light,usingKNO3aqueous solution as simulation wastewate to research the photocatalytic on thedegradation of nitrate.The results demonstrated that: TiO2nanotubes that dope S candegrade the NO3-well.We also researc the effect of the initial concentration ofNO3-,concentration of hole trapping agen on the degradation of NO3-and find the betterreaction conditions. Using the HCOOH as hole trapping agent can promote the reactionmore better。Initial concentration of NO3-and concentration of hole trapping agent is50mg/L and0.04mol/L,the photocatalytic reaction time is150min,the conversion rate ofNO3--N、removal rate of N,selectivity to N2is87.0,78.6%and90.3%. In this paper， the adsorption performance of H2TiO3.nH2O nanotubes to MBaqueous solution were also investigated. The results showed that H2TiO3.nH2Onanotubes adsorbed MB with opposite charges attraction each other. Initialconcentration of MB aqueous solution is40mg/L, temperature is50℃, pH is10, theamount of H2TiO3.nH2O nanotubes is0.25g/L, and the adsorption got to saturation after15min. The saturated adsorption amount is129.4mg/g.