Electrochimica Acta 46 (2000) 381 – 387 Comparison of the performance of a reactor equipped with a Ti/Pt and an SS anode for simultaneous cyanide removal and copper recovery L. Szpyrkowicz a, *, S.N. Kaul b , E. Molga c , M. DeFaveri d a Department of Enironmental Sciences, Uniersity of Venice, Dorsoduro 2137, 30123 Venice, Italy b National Enironmental Engineering Research Institute, Nagpur 440 020, India c Chemical and Process Engineering Department, Warsaw Technical Uniersity, ul. Warynskiego 1, 00 645 Warsaw, Poland d Faculty of Agriculture, Catholic Uniersity of Piacenza, . Emilia Parmense 84, 29100 Piacenza, Italy Received 26 November 1999; received in revised form 24 March 2000 Abstract The paper presents the results of a study on the destruction of copper complexed cyanides and the simultaneous recovery of copper in a lab-scale batch electrochemical reactor. The performance of the reactor equipped with a stainless steel (SS) plate anode is compared with the data relative to the process conducted with a Ti/Pt anode having the same overall size. Both reactors operated at various initial pH values under galvanostatic conditions. Under highly alkaline conditions in situ generation of a CuO catalyst on the anode surface was observed in both the reactors. The observed mass transport coefficient, showing both the effects of reaction kinetics and mass transfer, was a function of pH value and, only secondly, of the anode material. The highest value of (k l A ) obs , equal to 0.24033 cm 3 s -1 was obtained for a Ti/Pt anode reactor operating at the pH of 13. Under these very alkaline conditions the performance of the reactor equipped with the Ti/Pt anode at high initial Cu concentration proved slightly better than the performance with the SS anode. The energy consumption for the pH 13 was a function E =a /[Cu] +b, where a and b are the constants characteristic for each of the two reactors. © 2000 Elsevier Science Ltd. All rights reserved. Keywords: Cyanide electro-oxidation; Ti/Pt anode; SS anode; Cu electrodeposition; Metal plating wastewater www.elsevier.nl/locate/electacta electrocatalytic properties towards cyanide oxidation. Particular problems arise when dealing with the cyanide complexed by such metals as iron, copper or zinc, due to the high chemical stability of these complexes. The electroxidation of complexed cyanide was found feasi- ble, but it manifests a slower kinetics as compared to the electroxidation of free cyanide [6–9]. It was found that under particular conditions the process can, how- ever, be enhanced by the presence of copper ions in the solution. In this case the formation of some kind of deposit was noticed on the anode surface at long elec- trolysis time. Hine et al. [4] postulated that this dark blue or black deposit consists of cupric oxyhydroxide. Hwang et al. [7] analyzed the film deposited on the 1. Introduction Destruction of the cyanide present in solution in the ionic form using electrochemical methods, as an alter- native to a traditional chemical oxidation, has been proved to be feasible by several authors [1–5]. For the removal of simple cyanide various anode materials were successfully used: Pt, Ni, PbO 2 . All of them manifested * Corresponding author. Tel.: +39-41-5298591; fax: +39- 41-2578591. E-mail address: lidia@unive.it (L. Szpyrkowicz). 0013-4686/00/$ - see front matter © 2000 Elsevier Science Ltd. All rights reserved. PII:S0013-4686(00)00595-8