Influences of the operational variables on electrochemical treatment of chelated Cu(II) in alkaline solutions using a membrane cell

BACKGROUND: The electrochemical recovery of copper and chelating agent from their complex solution using a membrane flow cell was investigated. The parameters electrolysis time, solution pH, current density, and temperature were investigated. RESULTS: Electrochemical investigation indicated that chelating ligands can be recovered by the electrodeposition of copper ions on the cathode. For copper and EDTA recovery, the results indicated that recovery efficiency was affected by time, current density, and temperature. The recovery process was not influenced by pH in the range studied (pH 8-12), which can be explained by the low variation in the conditional stability constant, i.e. Delta log(10) K' <= 0.7, over the pH range. However, when NTA, EDTA, and DTPA were compared, the results indicated that the recovery efficiency decreased as the conditional stability constant of the chelating agent-Cu(II) complex increased. The maximum current efficiency of copper and EDTA recovery after 5 h of treatment was approximately 85%, whereas the recovery was 80% of the initial concentration (0.05 mol L-1) at a current density of 1 A dm(-2), temperature of 333 K, and pH of 10. CONCLUSION: Relatively high recovery efficiency makes the process fairly sustainable and hinders the discharge of copper ions and chelating ligands as pollutants into the environment. (C) 2016 Society of Chemical Industry