TiO₂-photocatalytic reduction of pentavalent and trivalent arsenic: production of elemental arsenic and arsine.
Heterogeneous photocatalytic reduction of As(V) and As(III) at different concentrations over TiO(2) under UV light in deoxygenated aqueous suspensions is described. For the first time, As(0) was unambiguously identified together with arsine (AsH(3)) as reaction products. As(V) reduction requires the presence of an electron donor (methanol in the present case) and takes place through the hydroxymethyl radical formed from methanol oxidation by holes or hydroxyl radicals. On the contrary, As(III) reduction takes place through direct reduction by the TiO(2)-conduction band electrons. Detailed mechanisms for the photocatalytic processes are proposed. Although reduction to solid As(0) is convenient for purposes of As removal from water as a deposit on TiO(2), attention must be paid to formation of AsH(3), one of the most toxic forms of As, and strategies for AsH(3) treatment should be considered.
Gerencia Química, Comisión Nacional de Energía Atómica, Avenida General Paz 1499, 1650 San Martín, Prov. de Buenos Aires, Argentina.
Ivana K
IK
Levy
Martín
M
Mizrahi
Gustavo
G
Ruano
Guillermo
G
Zampieri
Félix G
FG
Requejo
Marta I
MI
Litter
D001151:Arsenic / Q000737:chemistry* / Q000528:radiation effects; D001152:Arsenicals / Q000737:chemistry / Q000528:radiation effects; D002384:Catalysis; D010084:Oxidation-Reduction; D055668:Photochemical Processes; D014025:Titanium / Q000737:chemistry* / Q000528:radiation effects; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000528:radiation effects
D001152:Arsenicals; D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D014025:Titanium; D001151:Arsenic; C006633:arsine