SUNLIGHT-INDUCED PHOTOCHEMISTRY OF AQUEOUS-SOLUTIONS OF HEXACYANOFERRATE(II) AND HEXACYANOFERRATE(III) IONS

Photochemically induced processes in alkaline aqueous solutions of hexacyanoferrate(II) and -(III) were investigated in detail. The studies were conducted in the presence or absence of a titanium(IV) oxide semiconductor photocatalyst utilizing sunlight as the irradiation source. It was established that the cyanide ion liberated by photodissociation from thermodynamically stable iron cyano species can be photocatalytically oxidized via cyanate and nitrite all the way to nitrate. In addition, all oxidation processes are enhanced when the photocatalyst was present in the irradiated solution. The results obtained may have ramifications for the possible uses of solar power for the efficient treatment of large quantities of precious metals-mill tailings wastes containing various cyanide species.