title: The synthesis of TiO2 and TiO2-Pt and their application in the removal of Cr (VI).
abstract: The deposition of noble metal on titanium dioxide (TiO2) has been considered as an effective strategy to improve the activity of TiO2. In this paper, TiO2 nanoparticles were prepared via a sol-gel route, followed by heat treatment at elevated temperatures. TiO2-Pt catalyst was prepared by deposition of platinum (Pt) on the surface of as-prepared TiO2 nanoparticles. TiO2 and TiO2-Pt were characterized by X-ray diffraction, transmission electron microscopy, Raman spectroscopy, ultraviolet-visible differential reflectance spectra and infrared spectroscopy. TiO2 and TiO2-Pt were used as heterogeneous catalysts for the removal of Cr (VI) under ultraviolet-light illumination. TiO2 prepared at low temperature had smaller particle size and higher specific surface area, and consequently had higher activity on the removal of Cr (VI). The Pt deposited on the surface of TiO2 favoured the separation of photo-produced electrons (e-) and holes (h+), inhibited the recombination of e- and h+, and enhanced Cr (VI) removal. However, its blocking of active sites also inhibited the removal of Cr (VI). The deposition of 1% (wt.%) Pt to TiO2 produced the optimum activity for the removal of Cr (VI). A lower pH favoured the adsorption of Cr (VI) on the surface of TiO2, and correspondingly enhanced the removal of Cr (VI).
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, P.R. China. fanjianwei@tongji.edu.cn
authors.forename: Jian-Wei
authors.initials: JW
authors.lastname: Fan
authors.forename: Xiang-Hu
authors.initials: XH
authors.lastname: Liu
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
mesh_terms: D002384:Catalysis; D002857:Chromium / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D055668:Photochemical Processes; D010984:Platinum / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet; D013059:Spectrum Analysis, Raman; D014025:Titanium / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D014874:Water Pollutants, Chemical; D002857:Chromium; C009495:titanium dioxide; C074702:chromium hexavalent ion; D010984:Platinum; D014025:Titanium