title: Photocatalytic removal of M(2+) (Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+) and Ag(+)) over new catalyst CuCrO(2).
abstract: The metal ions M(2+) (Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+) and Ag(+)) are potentially toxic. Their electro deposition has been carried out in aqueous air-equilibrated CuCrO(2) suspension upon visible illumination. The delafossite CuCrO(2) is p-type semiconductor characterized by a low band gap (1.28 eV) and a long-term chemical stability. The corrosion rate is found to be 10(-2) micromol m(-2)month(-1) in aqua regia. The oxide has been elaborated through nitrate route where the specific surface area is increased via the surface/bulk ratio. A correlation exists between the dark M(2+) adsorption, the redox potential of M(2+/0) couple and the conduction band of CuCrO(2) positioned at -1.06 V(SCE). Ag(+) cannot be photoreduced because of its positive potential located far above the valence band. By contrast, Zn(2+) is efficiently deposited due to the large driving force at the interface. The improved photoactivity of copper with a deposition percentage (90%) is attributed to the strong dark adsorption onto the surface catalyst. The results indicate a competitive effect with the water reduction; it has been observed that the M(2+) deposition goes parallel with the hydrogen evolution. Such behavior is attributed to the low H(2) over voltage when ultra fine aggregate of M islands are photodeposited onto CuCrO(2) substrate.
authors.affiliation: Laboratoire de Stockage et de Valorisation des énergies Renouvelables, Faculty of Chemistry (USTHB), BP 32, 16111 Algiers, Algeria.
authors.forename: W
authors.initials: W
authors.lastname: Ketir
authors.forename: A
authors.initials: A
authors.lastname: Bouguelia
authors.forename: M
authors.initials: M
authors.lastname: Trari
mesh_terms: D002384:Catalysis; D002840:Chromates / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D008670:Metals / Q000302:isolation & purification*; D010777:Photochemistry
chemical_list: D002840:Chromates; D008670:Metals; D003300:Copper