Competitive Removal of Lead(II), Copper(II), and Cadmium(II) Ions through a Bulk Liquid Membrane Containing Macrocyclic Crown Ethers and Oleic Acid as Ion Carriers

Abstract

The competitive transport in equimolar mixtures of Cu(II), Cd(II), and Pb(II) ions from an aqueous source phase (CM = 0.0001 mol·L−1) through bulk liquid membranes (BLMs) using tetra aza-14-crown-4 (A414C4) and oleic acid (OA) as a cooperative ion carrier has been investigated. The BLMs were used to experimentally determine the transport behavior of Cu(II), Cd(II), and Pb(II). So, the influence of chemical parameters (i.e., macrocycle molecular structure, macrocyclic and fatty acid concentrations in the membrane phase, perchlorate concentration in the source phase, and the concentration of HCl in the stripping phase) was assessed for each metal ion. Among the examined ligands, A414C4 had the best transport efficiency. The initial fluxes and transport selectivity of the BLMs with A414C4 and OA were: Pb(II) > Cu(II) > Cd(II). Moreover, the influence of Zn(II), Co(II), and Ni(II) ions on the initial fluxes, selectivity coefficient, and removal percentage of Pb(II), Cu(II), and Cd(II) ions in the BLMs was investigated. The sequences of ion initial fluxes and transport selectivity have negligible changes as: Pb(II) > Cu(II) > Zn(II) > Cd(II) > Co(II) > Ni(II).