Catalysis of Dissolved and Adsorbed Iron in Soil Suspension for Chromium(VI) Reduction by Sulfide

doi:10.1016/S1002-0160(06)60090-8

Pedosphere

Volume 16, Issue 5, October 2006, Pages 572-578

https://doi.org/10.1016/S1002-0160(06)60090-8 Get rights and content

ABSTRACT

The kinetics of Cr(VI) reduction by sulfide in soil suspensions with various pHs, soil compositions, and Fe(II) concentrations was examined using batch anaerobic experimental systems at constant temperature. The results showed that the reaction rate of Cr(VI) reduction was in the order of red soil < yellow-brown soil < chernozem and was proportional to the concentration of HCl-extractable iron in the soils. Dissolved and adsorbed iron in soil suspensions played an important role in accelerating Cr(VI) reduction. The reaction involved in the Cr(VI) reduction by Fe(II) to produce Fe(III), which was reduced to Fe(II) again by sulfide, could represent the catalytic pathway until about 70% of the initially present Cr(VI) was reduced. The catalysis occurred because the one-step reduction of Cr(VI) by sulfide was slower than the two-step process consisting of rapid Cr(VI) reduction by Fe(II) followed by Fe(III) reduction by sulfide. In essence, Fe(II)/Fe(III) species shuttle electrons from sulfide to Cr(VI), facilitating the reaction. The effect of iron, however, could be completely blocked by adding a strong Fe(II)-complexing ligand, 1,10-phenanthroline, to the soil suspensions. In all the experiments, initial sulfide concentration was much higher than initial Cr(VI) concentration. The plots of In c[Cr(VI)] versus reaction time were linear up to approximately 70% of Cr(VI) reduction, suggesting a first-order reaction kinetics with respect to Cr(VI). Elemental sulfur, the product of sulfide oxidation, was found to accelerate Cr(VI) reduction at a later stage of the reaction, resulting in deviation from linearity for the In c[Cr(VI)] versus time plots.

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Citation Excerpt :
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Catalysis of Dissolved and Adsorbed Iron in Soil Suspension for Chromium(VI) Reduction by Sulfide

ABSTRACT

Water Research

Geochem. Cosmochim. Acta.

Marine Chemistry

Applied Geochemistry

Dechlorination of carbon tetrachloride by Fe(II) associated with goethite

Environ. Sci. Technol.

Kinetics and pH dependence of chromium(VI) reduction by iron(II)

Environ. Sci. Technol.

Influence of mineral surfaces on chromium(VI) reduction by iron(II)

Environ. Sci. Technol.

Heavy metals in soil contaminated by coal mining activity

Acta Pedologica Sinica

Surface-catalyzed chromium(VI) reduction: Reactivity comparisons of different organic reductants and different oxide surfaces

Environ. Sci. Technol.

Surface-catalyzed chromium(VI) reduction: The TiO2-CrVI-Mandelic acid system

Environ. Sci. Technol.

Chromate removal from aqueous wastes by reduction with ferrous ion

Environ. Sci. Technol.

Kinetics of chromate reduction by ferrous ions derived from hematite and biotite at 25 °C

American Journal of Science

Chromate reduction by subsurface soils under acidic conditions

Soil Sci. Soc. Am. J.

Redox interactions of Cr(VI) and substituted phenols: Kinetic investigation

Environ. Sci, Technol.

Surface-catalyzed chromium(VI) reduction: The TiO₂-Cr^VI-Mandelic acid system