Авторы: Sharma V., Burnett C., Yngard R.

2005 г.

Envir.Sci.Techn.

      Copper(I) cyanide (Cu(CN)4 3-) in the gold mine industry presents the biggest concern in cyanide management because it is much more stable than free cyanide. Cu(CN)4 3- is highly toxic to aquatic life; therefore, environmentally friendly techniques are required for the removal of Cu(CN)4 3- from gold mine effluent. The oxidation of Cu(CN)4 3- by iron- (VI) (FeVIO4 2-, Fe(VI)) and iron(V) (FeVO4 3-, Fe(V)) was studied using stopped-flow and premix pulse radiolysis techniques. The stoichiometry with Fe(VI) was determined to be 5HFeO4 - + Cu(CN)4 3- + 8H2O f 5Fe(OH)3 + Cu2+ + 4CNO- +3/2O2 + 6OH-. The rate law for the oxidation of Cu(CN)4 3- by Fe(VI) was found to be first-order with each reactant. The rates decreased with increasing pH and were mostly related to a decrease in concentration of reactive protonated Fe(VI) species, HFeO4 -. A mechanism is proposed that agrees with the observed reaction stoichiometry and rate law. The rate constant for the oxidation of Cu(CN)4 3- by Fe(V) was determined at pH 12.0 as 1.35 ( 0.02  107 M-1 s-1, which is approximately 3 orders of magnitude larger than Fe(VI). Results indicate that Fe(VI) is highly efficient for removal of cyanides in gold mill effluent.

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