Selective separation of potentially toxic elements from simulated nickel-plating wastewater using rotating disk ultrafiltration membrane

Abstract

This study proposes a novel approach for removing potentially toxic metal contaminants from industrial electroplating effluents using a rotating disk ultrafiltration membrane (RDM) with copolymer of maleic acid and acrylic acid (PMA) as the complexing agent. The effects of pH and P/M (mass ratio of PMA to metal ions) on metal rejection were investigated, achieving an optimal removal rate of 98 % at pH 6.0 and P/M 8. The shear-induced orderly dissociation-ultrafiltration (SIOD-UF) process was employed to selectively separate Zn(II), Cr(III), Ni(II), and Cu(II), with separation coefficients of β_Zn/Cr = 95.5, β_Cr/Ni = 42.0, and β_Ni/Cu = 47.3. Computational fluid dynamics (CFD) analysis was utilized to determine shear rate distribution, and the critical shear rates (γc) of PMA-metal complexes were calculated as 1.14 × 10⁵, 1.48 × 10⁵, 2.07 × 10⁵, and 1.21 × 10⁴ s⁻¹ for PMA-Cr, PMA-Ni, PMA-Cu, and PMA-Zn, respectively. In the final stage, Cu(II) was separated simultaneously with the regeneration of PMA. SIOD-UF is an efficient and selective metal separation method, free of additional acid or alkali consumption, providing a promising green solution for industrial wastewater treatment.