Destruction of cyanide and thiocyanate by ferrate [Iron(VI)]

A cyanide-laden effluent of the gold mining industry must be treated before it can be released to the aquatic environment. Current treatment methods such as natural degradation, sulfur based, hydrogen peroxide, ozonation, and alkaline chlorination are not adequate for meeting newer treatment standards. A new chemical oxidant that utilizes iron in the +6 oxidation state, ferrate [Fe(VI)] was studied to oxidize cyanides in gold mill wastewater. Reactions of cyanide and thiocyanate with Fe(VI) were analyzed to determine kinetic parameters, stoichiometry, and products. The complete removal of cyanide and thiocyanate can be achieved in seconds to minutes with the formation of less harmful products. Destruction of cyanide resulted in cyanate while sulfate and cyanate were the products of thiocyanate oxidation. Ferrate is therefore a suitable candidate as a new environmental friendly oxidant for gold mining wastewater. © 2003 SDU. All rights reserved.