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REDUCTIVE DEHALOGENATION OF HEXACHLOROETHANE, CARBON TETRACHLORIDE, AND BROMOFORM BY ANTHRAHYDROQUINONE DISULFONATE AND HUMIC ACID
Citation:
Curtis, G. P. AND M. Reinhard. REDUCTIVE DEHALOGENATION OF HEXACHLOROETHANE, CARBON TETRACHLORIDE, AND BROMOFORM BY ANTHRAHYDROQUINONE DISULFONATE AND HUMIC ACID. ENVIRONMENTAL SCIENCE & TECHNOLOGY 28(13):2393-2401, (1994).
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Description:
The reductive dehalogenation of hexachloroethane (CzCLj), carbon tetrachloride (CC14), and bromoform (CHBr3) was examined at 50 “C in aqueous solutions containing ei- ther (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 CC4 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 reduc- tion potentials.
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REDUCTIVE DEHALOGENATION OF HEXACHLOROETHANE, CARBON TETRACHLORIDE, AND BROMOFORM BY ANTHRAHYDROQUINONE DISULFONATE AND HUMIC ACID
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