Copper Electrodeposition and Oxidation of Complex Cyanide from Wastewater in an Electrochemical Reactor with a Ti/Pt Anode

Abstract

The paper presents the results of a study on the simultaneous electrooxidation of cyanides and recovery of copper as a metallic deposition on the cathode from weak concentration rinse wastewater in an electrochemical reactor with a Ti/Pt anode. Both a direct electrooxidation process and an indirect electrooxidation in a chloride-rich medium proved feasible, with direct electrooxidation being preferable because of the lower energy consumption. The results show that the process of the direct electrooxidation under alkaline conditions leads to the formation of an electrocatalytic film on the anode. Simultaneous copper electrodeposition on the cathode is feasible and economically convenient, particularly if conducted at pH 13 or higher. The process can be described by the pseudo-first-order kinetics, with the rate constant for Cu removal equal to 0.013 h -1 for very alkaline conditions. Energy consumed for copper electrodeposition proved to be inversely proportional to the initial Cu concentration. For wastewater bearing 1100 mg dm -3 Cu, 5.46 kWh is needed to eliminate 1 kg of metal. The current efficiency for chemical oxygen demand removal reaching 100% or higher was obtained, indicating reactions other than electrooxidation occurring simultaneously. Under the best conditions, the total cyanide concentration was lowered from 250 to 7.9 mg dm -3 .

Application of a novel strategy—Coordination polymerization precipitation to the treatment of Cu2+-containing wastewaters

“…[25][26][27][28]. As a result, copper(II) was selected as a representation of heavy metal in this paper.…”

Electrochemical studies of gold ore processing wastewater containing cyanide, copper, and sulfur compounds

“…Electrochemical methods for treating copper cyanide solutions have been investigated by numerous researchers [9][10][11][12][13][14][15][16][17][18][19][20]. In electrochemical methods, while cyanide is oxidized to cyanate at the anode, copper is recovered at the cathode avoiding copper precipitation.…”

Characterization of the catalytic films formed on stainless steel anodes employed for the electrochemical treatment of cuprocyanide wastewaters

“…In this case, the formation of a surface film on the anode which exhibited electrocatalytic properties was observed [12][13][14][15]. The best performance for the destruction of free cyanides has been achieved in reactors equipped with platinum and platinum-modified anodes [16][17][18][19]. The elevated cost of these materials has imposed a new trend in the investigation directed to testing alternate materials for electrodes fabrication.…”

“…In this way, comparison of the efficiency of a reactor equipped with either a Ti/Pt or a plated stainless steel anode operating at an alkaline pH of 13 [19], proved the performance of the former to be only slightly better than the performance with the modified SS anode. Though the results of treatment depended to some extent on the anode material, the formation of the electrocatalytic film on the surface of the anodes mainly depended on the chemical, electrical and hydrodynamic conditions under which the electrochemical reactor operated (applied potential and current, chemical composition of the electrolytic solution and the hydrodynamic regimes in the reactor) [12,[16][17][18][19][20][21][22][23]. It was demonstrated that the type of mixing and its intensity strongly affected the performance of the electrochemical reactor in terms of single pollutants: cyanides and copper, which correlated well with the extent of deposition for the electrocatalytic anodic film [22,23].…”