Application of hydrophobic β-cyclodextrin polymer in separation of metal ions by plasticized membranes

In the present work the hydrophobic β-cyclodextrin (β-CD) polymers have been used as macrocyclic ion carriers for separation of metal ions from dilute aqueous solutions by transport across polymer inclusion membranes. The β-CD polymers, serving as ion carriers, were prepared by cross-linking β-CD with alkenyl (nonenyl and dodecenyl) succinic anhydride derivatives in anhydrous N,N-dimethylformamide in the presence of NaH. The metal ions were transported from aqueous solutions containing heavy metal ions through plasticizer triacetate membranes into distilled water. In case of competitive transport of Cu(II), Co(II), Ni(II) and Zn(II) ions through plasticized immobilized membranes the selectivity of process is controlled via formation of ion pairs of hydroxyl groups with metal ions. The cation transport properties were interpreted by an induced-fit mechanism. The polymer of β-CD, i.e., nonenyl derivative used as ionic carrier for competitive transport of Cu(II), Co(II), Ni(II) and Zn(II) ions shows preferential selectivity order: Cu(II) > Co(II) > Ni(II) > Zn(II).