Light-induced reduction of rhodium(III) and palladium(II) on titanium dioxide dispersions and the selective photochemical separation and recovery of gold(III), platinum(IV), and rhodium(III) in chloride media

Journal Article · Wed Dec 03 04:00:00 EST 1986 · Inorg. Chem.; (United States)

DOI:https://doi.org/10.1021/ic00245a010· OSTI ID:6712580

Borgarello, E; Serpone, N; Emo, G; Harris, R; Pelizzetti, E; Minero, C

Irradiation of aqueous TiO/sub 2/ dispersions containing palladium(II) or rhodium(III) chloride salts with AM1 simulated sunlight leads to the photoreduction of these metals, which are deposited on the semiconductor particle surface. Oxygen is detrimental to the photoreduction of rhodium(III) but not the photoreduction of palladium(II). However, in both cases the reduction process is most efficient if the solution contains CH/sub 3/OH, which acts to scavenge valence band holes of the illuminated TiO/sub 2/ semiconductor. The selective photoreduction and recovery of precious metals from a dilute solution (as might be found in industrial wastes) have been investigated for a mixture of gold(III), platinum(IV), and rhodium(III) chloride salts as a function of various parameters (pH, presence or absence of O/sub 2/, presence or absence of a hole scavenger, and the concentration of the semiconductor). At pH 0, gold is easily separated from platinum and rhodium. The rate of photoreduction of gold(III) on TiO/sub 2/ is nearly independent of the concentration of the semiconductor, under the experimental conditions employed; the limiting rate is 2.7 x 10/sup -7/ M s/sup -1/. The potential utility of this selective photochemical technique is discussed.

• Research Organization: Concordia Univ., Montreal, Quebec
• OSTI ID: 6712580
• Journal Information: Inorg. Chem.; (United States), Journal Name: Inorg. Chem.; (United States) Vol. 25:25; ISSN INOCA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400105 -- Separation Procedures
400500* -- Photochemistry
ALCOHOLS
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISTRY
CHLORIDES
CHLORINE COMPOUNDS
DATA
ELEMENTS
EXPERIMENTAL DATA
GOLD
HALIDES
HALOGEN COMPOUNDS
HYDROXY COMPOUNDS
INDUSTRIAL WASTES
INFORMATION
MANAGEMENT
MATERIALS
MATERIALS RECOVERY
METALS
METHANOL
NONMETALS
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PALLADIUM
PH VALUE
PHOTOCHEMICAL REACTIONS
PHOTOCHEMISTRY
PLATINUM
PLATINUM METALS
PROCESSING
RECOVERY
REDUCTION
RHODIUM
SEMICONDUCTOR MATERIALS
SEPARATION PROCESSES
TITANIUM COMPOUNDS
TITANIUM OXIDES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
WASTE MANAGEMENT
WASTE PROCESSING
WASTES