Electrolytic recovery of binary metals and EDTA from strong complexed solutions

Abstract

Electrolytic recovery of binary Cu(II) and Pb(II) from solutions containing strong complexing agent EDTA (ethylenediaminetetraacetic acid) was studied in a two-chamber cell separating with a cation exchange membrane Neosepta CM-1. An equimolar solution of EDTA and total metals was focused. The iridium oxide coated on titanium (Ti/IrO 2) and stainless steel were used as the anode and cathode, respectively. Experiments were carried out at different current densities (18.5–185 A/m 2), initial catholyte pH (1.47–6), the total metal concentrations (5–20 mM) and their concentration ratios. It was shown that the deposition recovery of Cu(II) was faster and more efficient than that of Pb(II). Compared to single metal–EDTA solutions, lower metal recovery and current efficiency were obtained in binary solutions regardless of what metal concentration ratios. This was probably related to the deposit structure of binary metals onto the cathode.