Electrochemical recovery of copper complexed by DTPA and C12-DTPA from aqueous solution using a membrane cell

BACKGROUNDThe electrochemical recovery of copper from diethylenetriaminepentaacetic acid (DTPA) and C-12-DTPA (a surface-active derivative of DTPA) complex solutions was investigated in a membrane flow cell. Electrolysis time, solution flow rate, applied current density, and solution pH were evaluated. RESULTSThe chelating surfactant C-12-DTPA can promote the kinetics of copper electrodeposition more than DTPA depending on the experimental conditions. At a current density of 30 A m(-2), a solution flow rate of 0.6 L min(-1), and pH 10 after 180 min treatment, the copper recovery and current efficiency were 50% and 43.3%, respectively, in the Cu(II)-DTPA system and about 65% and 53.6%, respectively, in the Cu(II)-C-12-DTPA system. The differences in the amount of recovery could be explained in terms of differences in the diffusion of copper complexes with DTPA and C-12-DTPA to the cathode, as well as their solution behavior and pH-dependent conditional stability constants (log(10)K'(3-)(CuDTPA)). CONCLUSIONElectrochemical methods could be effectively combined with foam flotation for the chelating surfactant C-12-DTPA, to recover copper and C-12-DTPA. This makes the overall treatment more sustainable, and can be helpful in complying with the increasingly stringent environmental regulations. (c) 2017 Society of Chemical Industry