A semi-micro-method for the determination of quinoid groups in humic acids

Glebko, L. I.; Ulkina, J. U.; Maximov, O.B.

doi:10.1007/bf01215962

Cited by 9 publications

(6 citation statements)

References 12 publications

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“…The transformation of C2C16 and CCl4 in NOM solutions with Fez+ or HS-as the bulk electron donors is consistent with NOM acting as electron transfer mediator and hydroquinone groups being the reactive sites. This proposition is based on (1) the slow reduction observed with only the bulk electron donor, (2) the observed reduction of CC14 and C2Cl6 by ionized AHQDS in the model system studied here, (3) the observed increase in reaction rate with increasing pH in systems containing either AHQDS or NOM, and (4) previous reported reactions indicating that both HS-and Fez+ can reduce the quinone groups in simple quinones (17,511 as well as in humic acid (14)(15)(16). Alternative reaction pathways could also play an important role in the transformations that we observed.…”

Section: Discussionmentioning

confidence: 95%

“…Studies of nitroaromatic reduction by reduced iron porphyrins and hydroquinones suggest possible reaction pathways for the reduction of halogenated hydrocarbons. It has been hypothesized that iron porphyrins and hydroquinones are electron transfer mediators that form highly reactive, reduced intermediates that reduce the oxidized contaminant as shown in Scheme 1 (10,14). Once Scheme 1 bulk donor n-e" mediator,,,.…”

Section: Introductionmentioning

confidence: 99%

“…Spectroscopic and stoichiometric evidence indicate that Fe2+ quantitatively and selectively reduces quiñones in humic acid to hydroquinones (14)(15)(16). Similarly, HS™ reduces quinone groups to hydroquinones in simple model compounds (17), and it has been suggested that HS™ also reduces quinone groups to the corresponding hydroquinone group in humic acid (18).…”

Section: Introductionmentioning

confidence: 99%

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Reductive Dehalogenation of Hexachloroethane, Carbon Tetrachloride, and Bromoform by Anthrahydroquinone Disulfonate and Humic Acid

Curtis¹,

Reinhard²

1994

Environ. Sci. Technol.

215

200

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The reductive dehalogenation of hexachloroethane (CzCLj), carbon tetrachloride (CC14), and bromoform (CHBr3) was examined at 50 "C in aqueous solutions containing either (1) 500 pM of 2,6-anthrahydroquinone disulfonate (AHQDS), (2) 250 pM Fe2+, or (3) 250 pM HS-. The pH ranged from 4.5 to 11.5 for AHQDS solutions and was 7.2 in the Fez+ solutions and 7.8 in the HS-solutions. The observed disappearance of C&16 in the presence of AHQDS was pseudo-first-order and fit k'ccb = ko[A(OH)zI + kdA(0H)O-I + kz[A(O)~~-l whereA(OH)2, A(0H)O-, and A(0)n2-represent the concentrations of the three forms of the AHQDS in solution. The values of ko, kl, and kz were -0,0.031, and 0.24 M-l s-l, respectively. The addition of 25 mg of C/L of humic acid or organic matter extracted from Borden aquifer solids to aqueous solutions containing 250 I~.M HS-or Fe2+ increased the reduction rate by factors of up to 10. The logarithms of the rate constants for the disappearance of CzCl6 and C C 4 in seven different experimental systems were significantly correlated; log k'cc14 = 0.64 log k'czc~ -0.83 with r2 = 0.80. The observed trend in reaction rates of C&l6 > CCl4 > CHBr3 is consistent with a decreasing trend in one-electron reduction potentials.

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Section: Discussionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Reductive Dehalogenation of Hexachloroethane, Carbon Tetrachloride, and Bromoform by Anthrahydroquinone Disulfonate and Humic Acid

Curtis¹,

Reinhard²

1994

Environ. Sci. Technol.

215

200

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“…Bivalent and total iron in ores has been determined by titrating first with K2Cr207 and then with Na2S203 after introduction of CuSCh (45). Addition of iron(II) and back titration with K2Cr207 has been used to determine quinoid groups in humic acids (97). Titration with Mohr's salt has been used to determine manganese, chromium, and vanadium in silicate rocks (25) and in steel (127), uranium in nuclear fuels (290), and the oxygen: uranium ratio in hyperstoichiometric uranium dioxide (289).…”

Section: Titration In 2804 Ormentioning

confidence: 99%

Amperometric titrations

Stock¹

1972

Anal. Chem.

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The period covered by this survey is from the previous review (271) through October, 1971. Unless otherwise specified, potentials are with respect to the saturated calomel electrode (SCE).Reviews of electroanalytical techniques (113) and of coulometric analysis (198) include amperometric titrimetry.Amperometric methods have been discussed with respect to industrial analyses (47, 114) and to complexometric

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“…(Winston-Salem, N. C.) 1978, 24, 621-626. (14) Gullbault, George (24) Szasz, Gabor; Gerhardt, Willie; Gruber, Wolfgang; Bernt, Erich Clin.…”

mentioning

confidence: 99%

Simultaneous determination of iron(II), iron(III), and total iron in sphagnum moss peat by programmable voltammetry on a graphite tubular electrode

Szydlowski¹,

Peck²,

Eggers³

et al. 1981

Anal. Chem.

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A semi-micro-method for the determination of quinoid groups in humic acids

Cited by 9 publications

References 12 publications

Reductive Dehalogenation of Hexachloroethane, Carbon Tetrachloride, and Bromoform by Anthrahydroquinone Disulfonate and Humic Acid

Reductive Dehalogenation of Hexachloroethane, Carbon Tetrachloride, and Bromoform by Anthrahydroquinone Disulfonate and Humic Acid

Amperometric titrations

Simultaneous determination of iron(II), iron(III), and total iron in sphagnum moss peat by programmable voltammetry on a graphite tubular electrode

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