A vibrational spectroscopic sup 18 O tracer study of pyrite oxidation

Journal Article · Sat Jun 01 00:00:00 EDT 1991 · Geochimica et Cosmochimica Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(91)90132-O· OSTI ID:5890886

Reedy, B J; Beattie, J K ^[1]; Lowson, R T ^[2]

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1. Univ. of Sydney (Australia)
2. Australian Nuclear Science and Technology Organisation, Sutherland (Australia)

Pyrite was oxidized under {sup 18}O{sub 2} gas in H{sub 2}{sup 16}O solutions, with and without added ferric ion, and the sulfate produced was analysed by vibrational spectroscopy to determine the relative amounts of sulfate isotopomers (S{sup 16}O{sub n}{sup 18}O{sub 4{minus}n}{sup 2{minus}}) formed. At 70C and pH 1, with no added Fe{sup 3+}, the majority of the sulfate formed was that which derived all four oxygen atoms from water (i.e., S{sup 16}O{sub 4}{sup 2{minus}}), but significant amounts of two other isotopomers, S{sup 16}O{sub 3}{sup 18}O{sup 2{minus}} and S{sup 16}O{sub 2}{sup 18}O{sub 2}{sup 2{minus}}, which derive one or two oxygen atoms from molecular oxygen were observed. When Fe{sup 3+} was added at the start under identical conditions, no S{sup 16}O{sub 2}{sup 18}O{sub 2}{sup 2{minus}} was observed. The major isotopomer formed was still S{sup 16}O{sub 4}{sup 2{minus}}, with S{sup 16}O{sub 3}{sup 18}O{sup 2{minus}} present as a minor product. Experiments which were performed at initial pH 7 yielded similar results, as did others performed at 20C, although the amounts of the minor isotopomers fromed vary with temperature. All of the results were confirmed by performing identical experiments with the source of the oxygen isotopes reversed, that is, by oxidixing pyrite under air in H{sub 2}{sup 18}O solutions and obtaining the same products in isotopic reverse.

• OSTI ID: 5890886
• Journal Information: Geochimica et Cosmochimica Acta; (United States), Vol. 55:6; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
PYRITE
CHEMICAL REACTION KINETICS
OXIDATION
EMISSION SPECTROSCOPY
ISOTOPE RATIO
OXYGEN 18
PH VALUE
QUANTITY RATIO
RAMAN SPECTROSCOPY
SULFATES
TRACER TECHNIQUES
VIBRATIONAL STATES
CHEMICAL REACTIONS
ENERGY LEVELS
EVEN-EVEN NUCLEI
EXCITED STATES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LASER SPECTROSCOPY
LIGHT NUCLEI
MINERALS
NUCLEI
OXYGEN COMPOUNDS
OXYGEN ISOTOPES
REACTION KINETICS
SPECTROSCOPY
STABLE ISOTOPES
SULFIDE MINERALS
SULFUR COMPOUNDS
580000* - Geosciences