Kinetics and Mechanisms of the Reactions of Chromium (VI) with Sulfur-containing Compounds in Aqueous Acid Solution

Kinetics and Mechanisms of the Reactions of Chromium (VI) with Sulfur-containing Compounds in Aqueous Acid Solution PDF Author: Dwight Craig Ramdon
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Category : Chromium
Languages : en
Pages : 740

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Kinetics and Mechanisms of the Reactions of Chromium (VI) with Sulfur-containing Compounds in Aqueous Acid Solution

Kinetics and Mechanisms of the Reactions of Chromium (VI) with Sulfur-containing Compounds in Aqueous Acid Solution PDF Author: Dwight Craig Ramdon
Publisher:
ISBN:
Category : Chromium
Languages : en
Pages : 740

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Kinetics and Mechanisms of Reactions of Chromium (VI) with Iron (II) Species

Kinetics and Mechanisms of Reactions of Chromium (VI) with Iron (II) Species PDF Author: James H. Espenson
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ISBN:
Category : Chemical kinetics
Languages : en
Pages : 318

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Equilibrium and Kinetic Studies in Aqueous Acidic Solutions of Chromium (III), Chromium (VI) and Cerium (IV)

Equilibrium and Kinetic Studies in Aqueous Acidic Solutions of Chromium (III), Chromium (VI) and Cerium (IV) PDF Author: James Ying-Peh Tong
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ISBN:
Category :
Languages : en
Pages : 520

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Studies of Chromium(VI) Reactions with Sulfur-containing Compounds

Studies of Chromium(VI) Reactions with Sulfur-containing Compounds PDF Author: Muirhead. Katharine Ann Myers
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Category :
Languages : en
Pages : 212

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Remediation of Chromium(VI) in the Vadose Zone

Remediation of Chromium(VI) in the Vadose Zone PDF Author: Min Ahn
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Category :
Languages : en
Pages :

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Immobilization and detoxification of chromium in the vadose zone is made possible by the existence of an effective reductant, SO2, that exists in a gaseous form at room temperature. Experimental studies were designed to characterize stoichiometry and kinetics of chromium reduction both in aqueous solutions at pH values near neutrality and in soil. First, batch experiments and elemental analyses were conducted to characterize the stoichiometry and kinetics of Cr(VI) reduction in water. The stoichiometric ratio of S(IV) removed to Cr(VI) removed ranged between 1.6 and 1.8. The overall reaction is believed to be the result of a linear combination of two reactions in which dithionate is an intermediate and sulfate is the stable oxidized product. The reaction was also rapid, with the half-time of about 45 minutes at pH 6 and about 16 hours at pH 7. A two-step kinetic model was developed to describe changes in concentrations of Cr(VI), S(IV), and S(V). Nonlinear regression was applied to obtain the kinetic parameters. The rate of reaction was assumed to be second-order with respect to [Cr(VI)] and first-order with respect to [S(IV)], and [S(V)]. The values for the rate coefficient for the first reaction (k1) were found to be 4.5 ("10%), 0.25 ("9.4%) (mM-2h-1) at pH 6 and 7, respectively. The values of the rate coefficient for the second reaction (k2) were 25 ("29%), 1.1 ("30%) (mM-2h-1) at pH 6 and 7, respectively. The reaction rate decreased as pH increased. Experiments showed that the rate at pH 7 was lower than that at pH 6 by one order of magnitude. Second, batch experiments and elemental analyses were conducted to characterize the stoichiometry and kinetics of Cr(VI) reduction in soil. The stoichiometric ratio of S(IV) removed to Cr(VI) removed was almost 2, which is slightly higher than that for the reaction in water. This higher value may be due to S(IV) oxidation by soil-derived Fe(III). The reaction was rapid, with the half-time less than 2 minutes, which is faster than in water. The rate coefficients, k1 and k2, were 22 ("41%) and 13 ("77%) (M-2h-1), respectively.

Nuclear Science Abstracts

Nuclear Science Abstracts PDF Author:
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ISBN:
Category : Nuclear energy
Languages : en
Pages : 882

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Pandex Current Index to Scientific and Technical Literature

Pandex Current Index to Scientific and Technical Literature PDF Author:
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ISBN:
Category : Medicine
Languages : en
Pages : 1318

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Technical Abstract Bulletin

Technical Abstract Bulletin PDF Author:
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ISBN:
Category : Science
Languages : en
Pages : 440

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Dissertation Abstracts International

Dissertation Abstracts International PDF Author:
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ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 1396

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Chromium Reactions in Geologic Materials

Chromium Reactions in Geologic Materials PDF Author:
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ISBN:
Category : Chromium
Languages : en
Pages : 328

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