title: TiO2/palygorskite composite nanocrystalline films prepared by surfactant templating route: synergistic effect to the photocatalytic degradation of an azo-dye in water.
abstract: Microfibrous palygorskite clay mineral and nanocrystalline TiO(2) are incorporating in the preparation of nanocomposite films on glass substrates via sol-gel route at 500°C. The synthesis involves a simple chemical method employing nonionic surfactant molecule as pore directing agent along with the acetic acid-based sol-gel route without direct addition of water molecules. Drying and thermal treatment of composite films lead to the elimination of organic material while ensure the formation of TiO(2) nanoparticles homogeneously distributed on the surface of the palygorskite microfibers. TiO(2) nanocomposite films without cracks consisted of small crystallites in size (12-16 nm) and anatase crystal phase was found to cover palygorskite microfibers. The composite films were characterized by microscopy techniques, UV-vis, IR spectroscopy, and porosimetry methods in order to examine their structural properties. Palygorskite/TiO(2) composite films with variable quantities of palygorskite (0-2 w/w ratio) were tested as new photocatalysts in the photo-discoloration of Basic Blue 41 azo-dye in water. These nanocomposite films proved to be very promising photocatalysts and highly effective to dye's discoloration in spite of the small amount of immobilized palygorskite/TiO(2) catalyst onto glass substrates. 3:2 palygorskite/TiO(2) weight ratio was finally the most efficient photocatalyst while reproducible discoloration results of the dye were obtained after three cycles with same catalyst. It was also found that palygorskite showed a positive synergistic effect to the TiO(2) photocatalysis.
authors.affiliation: Electrical Engineering Department, Technological-Educational Institute of Patras, GR-26334 Patras, Greece. estathatos@teipat.gr
authors.forename: E
authors.initials: E
authors.lastname: Stathatos
authors.forename: D
authors.initials: D
authors.lastname: Papoulis
authors.forename: C A
authors.initials: CA
authors.lastname: Aggelopoulos
authors.forename: D
authors.initials: D
authors.lastname: Panagiotaras
authors.forename: A
authors.initials: A
authors.lastname: Nikolopoulou
mesh_terms: D001391:Azo Compounds / Q000737:chemistry* / Q000528:radiation effects; D002384:Catalysis; D004396:Coloring Agents / Q000737:chemistry* / Q000528:radiation effects; D017616:Magnesium Compounds / Q000737:chemistry*; D053761:Nanocomposites / Q000737:chemistry*; D017830:Octoxynol / Q000737:chemistry; D010782:Photolysis; D017655:Silicon Compounds / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry; D014025:Titanium / Q000737:chemistry*; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000528:radiation effects; D018508:Water Purification / Q000379:methods
chemical_list: D001391:Azo Compounds; D004396:Coloring Agents; D017616:Magnesium Compounds; D017655:Silicon Compounds; D013501:Surface-Active Agents; D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D017830:Octoxynol; D014025:Titanium; C026325:attapulgite