Photo-assisted electrolytic decomplexation of Cu-EDTA and Cu recovery enhanced by H2O2 and electro-generated active chlorine

摘要

The performance of Cu-EDTA decomplexation and copper recovery by photo-assisted electrolysis (UPE) process using TiO2/Ti as anode and stainless-steel as cathode was explored by adding H2O2/Cl-. The Cu-EDTA decomplexation and Cu recovery were well fitted with a pseudo-first-order reaction model. The results indicated that with the addition of H2O2 into the UPE process (H2O2-UPE process), the kinetic constant of Cu-EDTA decomplexation was increased from 0.0677 min(-1) to 0.0880 min(-1), and the kinetic constant of Cu recovery was increased from 0.0607 min(-1) to 0.0749 min(-1). Similar enhancement was observed by adding Cl- into the UPE process (EC-UPE process), where the kinetic constant of Cu-EDTA decomplexation was increased from 0.0272 min(-1) to 0.0632 min(-1). Correspondingly, the kinetic constant of Cu recovery was increased from 0.0249 mine to 0.0565 min(-1). In the H2O2-UPE process, the efficiency of Cu-EDTA decomplexation and Cu recovery was optimal at the initial solution pH of 2.5-3.5; in the EC-UPE process, an optimum current density of 1.00 mA/cm(2) was obtained. Intermediates were detected in H2O2-UPE process and a decomplexation pathway was proposed. A different degradation pathway was concluded in the EC-UPE process. (C) 2016 Published by Elsevier B.V.