Voltammetric evaluation of the electrode material on the oxidation of cyanide catalyzed by copper ions

The cyanide oxidation on vitreous carbon (VC), stainless steel 304 (SS 304) and titanium (Ti) was investigated through a voltammetric study of cyanidesolutions also containing copper ions. Results showed that cyanide oxidation occurs by means of a catalytic mechanism involving adsorbed species as CN,Cu(CN)4 3 or Cu(CN)4 2 depending on the electrode material. It was observed that on VC, the adsorption of Cu(CN)4 3 controlled the oxidation rate. Instead, for SS 304 and Ti, the adsorption of CN controlled the global process. However, in all cases, the adsorption of Cu(CN)4 3 on the electrode surface was required for the catalytic oxidation of CN. Voltammetric experiments for solutions containing cyanide oxidation products, such as cyanogen (CN)2 and cyanate (CNO), confirmed that the adsorbed species mentioned above controlled the catalytic oxidation of CN depending on the electrode material. A voltammetric identification of the oxidation products showed that cyanogen, (CN)2 tended to adosorb on VC, while the formation of cyanate, CNO predominated on SS 304.