Selective separation of Cd(II), Zn(II) and Pb(II) from Pb-Zn smelter wastewater via shear induced dissociation coupling with ultrafiltration

Abstract

Treatment of Pb-Zn smelter wastewater via complexation-ultrafiltration (C-UF) was studied using copolymer of acrylic acid-maleic acid (PMA) as complexant. The complexing reaction kinetics of M (Cd(II), Pb(II) and Zn(II)) with PMA were examined for the first time and the pseudo-first-order model could be employed to simulate the reaction. The effects of the mass ratio of PMA to metal ions (P/M) and pH on the simultaneous removal of Cd(II), Zn(II) and Pb(II) via C-UF were investigated, and the optimized P/M and pH are 10 and 7.0, respectively. Furthermore, the shear stability of PMA-Cd, PMA-Zn and PMA-Pb complexes was investigated, and the corresponding critical shear rates (γc), the smallest shear rate at which the complexes begin to dissociate were 1.98×105, 1.81×104 and 1.38×105 s−1, respectively. The selective recovery of Cd(II), Zn(II) and Pb(II) from Pb-Zn Smelter wastewater as well as the regeneration of PMA were fulfilled by shear induced dissociation coupled with ultrafiltration (SID-UF) according to the difference of critical shear rates of PMA-M complexes, and the regenerated PMA showed almost the same complexation ability as the original.