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Ferrate(VI) oxidation of weak-acid dissociable cyanides.
Environ Sci Technol. 2008 Apr 15; 42(8):3005-10.ES

Abstract

Cyanide is commonly found in electroplating, mining, coal gasification, and petroleum refining effluents, which require treatment before being discharged. Cyanide in effluents exists either as free cyanide or as a metal complex. The kinetics of the oxidation of weak-acid dissociable cyanides by an environmentally friendly oxidant, ferrate(VI) (Fe(VI)O4(2-), Fe(VI)), were studied as a function of pH (9.1-10.5) and temperature (15-45 degrees C) using a stopped-flow technique. The weak-acid dissociable cyanides were Cd(CN)4(2-) and Ni(CN)4(2-), and the rate-laws for the oxidation may be -d[Fe(VI)]/dt = k[Fe(VI)][M(CN)4(2-)]n where n = 0.5 and 1 for Cd(CN)4(2-) and Ni(CN)4(2-), respectively. The rates decreased with increasing pH and were mostly related to a decrease in concentration of the reactive protonated Fe(VI) species, HFeO4(-). The stoichiometries with Fe(VI) were determined to be: 4HFeO4(-) + M(CN)4(2-) + 6H2O --> 4Fe(OH)3 + M(2+) + 4NCO(-) + O2 + 4OH(-). Mechanisms are proposed that agree with the observed reaction rate-laws and stoichiometries of the oxidation of weak-acid dissociable cyanides by Fe(VI). Results indicate that Fe(VI) is effective in removing cyanide in coke oven plant effluent, where organics are also present.

Authors+Show Affiliations

Chemistry Department, Florida Institute of Technology, 150 West University Boulevard, Melbourne, Florida 32901, USA.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

18497158

Citation

Yngard, Ria A., et al. "Ferrate(VI) Oxidation of Weak-acid Dissociable Cyanides." Environmental Science & Technology, vol. 42, no. 8, 2008, pp. 3005-10.
Yngard RA, Sharma VK, Filip J, et al. Ferrate(VI) oxidation of weak-acid dissociable cyanides. Environ Sci Technol. 2008;42(8):3005-10.
Yngard, R. A., Sharma, V. K., Filip, J., & Zboril, R. (2008). Ferrate(VI) oxidation of weak-acid dissociable cyanides. Environmental Science & Technology, 42(8), 3005-10.
Yngard RA, et al. Ferrate(VI) Oxidation of Weak-acid Dissociable Cyanides. Environ Sci Technol. 2008 Apr 15;42(8):3005-10. PubMed PMID: 18497158.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Ferrate(VI) oxidation of weak-acid dissociable cyanides. AU - Yngard,Ria A, AU - Sharma,Virender K, AU - Filip,Jan, AU - Zboril,Radek, PY - 2008/5/24/pubmed PY - 2008/7/26/medline PY - 2008/5/24/entrez SP - 3005 EP - 10 JF - Environmental science & technology JO - Environ Sci Technol VL - 42 IS - 8 N2 - Cyanide is commonly found in electroplating, mining, coal gasification, and petroleum refining effluents, which require treatment before being discharged. Cyanide in effluents exists either as free cyanide or as a metal complex. The kinetics of the oxidation of weak-acid dissociable cyanides by an environmentally friendly oxidant, ferrate(VI) (Fe(VI)O4(2-), Fe(VI)), were studied as a function of pH (9.1-10.5) and temperature (15-45 degrees C) using a stopped-flow technique. The weak-acid dissociable cyanides were Cd(CN)4(2-) and Ni(CN)4(2-), and the rate-laws for the oxidation may be -d[Fe(VI)]/dt = k[Fe(VI)][M(CN)4(2-)]n where n = 0.5 and 1 for Cd(CN)4(2-) and Ni(CN)4(2-), respectively. The rates decreased with increasing pH and were mostly related to a decrease in concentration of the reactive protonated Fe(VI) species, HFeO4(-). The stoichiometries with Fe(VI) were determined to be: 4HFeO4(-) + M(CN)4(2-) + 6H2O --> 4Fe(OH)3 + M(2+) + 4NCO(-) + O2 + 4OH(-). Mechanisms are proposed that agree with the observed reaction rate-laws and stoichiometries of the oxidation of weak-acid dissociable cyanides by Fe(VI). Results indicate that Fe(VI) is effective in removing cyanide in coke oven plant effluent, where organics are also present. SN - 0013-936X UR - https://www.unboundmedicine.com/medline/citation/18497158/Ferrate_VI__oxidation_of_weak_acid_dissociable_cyanides_ L2 - https://doi.org/10.1021/es0720816 DB - PRIME DP - Unbound Medicine ER -