title: Cr(VI) photocatalytic reduction: effects of simultaneous organics oxidation and of gold nanoparticles photodeposition on TiO2.
abstract: Commercial TiO(2) samples with different phase composition and surface area were tested as photocatalysts in the photoinduced reduction of Cr(VI) in aqueous suspensions at pH 3.7 under UV-visible light irradiation. This reaction was also coupled with the simultaneous photocatalytic oxidation of the pollutant azo dye Acid Orange 8 (AO8) and of formic acid, acting as hole scavengers. The co-presence of oxidizable and reducible species ensured better separation of photogenerated charge carriers, resulting in a higher rate of both organics' oxidation and Cr(VI) reduction, especially in the case of high surface area anatase TiO(2), having the strongest affinity for Cr(VI) and AO8, as demonstrated by competitive adsorption tests. The effects on Cr(VI) photocatalytic reduction of gold nanoparticles photodeposited on TiO(2) and of the Au loading were also investigated, aiming at ascertaining if this noble metal plays a role in the electron transfer processes involved in Cr(VI) reduction.
authors.affiliation: Dipartimento di Chimica Fisica ed Elettrochimica and CIMAINA, Università degli Studi di Milano, via Golgi 19, I-20133 Milano, Italy.
authors.forename: Maria Vittoria
authors.initials: MV
authors.lastname: Dozzi
authors.forename: Alessia
authors.initials: A
authors.lastname: Saccomanni
authors.forename: Elena
authors.initials: E
authors.lastname: Selli
mesh_terms: D001391:Azo Compounds / Q000737:chemistry / Q000528:radiation effects; D002384:Catalysis; D002857:Chromium / Q000737:chemistry* / Q000528:radiation effects; D004396:Coloring Agents / Q000737:chemistry / Q000528:radiation effects; D006046:Gold / Q000737:chemistry*; D008027:Light; D053768:Metal Nanoparticles / Q000737:chemistry*; D010084:Oxidation-Reduction; D055668:Photochemical Processes; D014025:Titanium / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000528:radiation effects
chemical_list: D001391:Azo Compounds; D004396:Coloring Agents; D014874:Water Pollutants, Chemical; D002857:Chromium; C009495:titanium dioxide; C074702:chromium hexavalent ion; D006046:Gold; D014025:Titanium