Ion imprinted polymer solid phase extraction (IIP-SPE) for preconcentrative separation of Erbium(III) from adjacent lanthanides and yttrium

Erbium(III) ion imprinted polymer (IIP) materials were prepared by photochemical polymerization of the ternary complex, Erbium(III)-5,7-dichloroquinoline-8-ol-4-vinylpyridine, with methyl methacrylate (functional monomer) and ethylene glycol dimethacrylate (crosslinking monomer) in the presence of 2,2'-azobisisobutyronitrile (initiator). The synthesis was carried out in 2-methoxy ethanol (porogen) medium and the resultant material was filtered, dried and powdered to form unleached polymer particles. The imprint ion (erbium(III)) was removed by stirring the above particles with 6 mol/l HCl to obtain leached polymer particles. These leached particles are termed erbium(III) ion imprinted polymer (IIP) particles as it selectively rebind erbium(III) ions. Non-imprinted/control polymer (CP) particles were similarly prepared without the imprint ion. CP and unleached and leached IIP particles were characterized by XRD, microanalysis, and UV-visible spectrophotometric studies. Various parameters that influence ion imprinted polymer-solid phase extraction such as pH, weight of polymer particles, preconcentration time, elution time, eluent volume, and aqueous phase volume were varied and optimal conditions for each parameter for quantitative enrichment of erbium(III) were established. The selectivity coefficients of erbium(III) ion over Y, Dy, Ho and Tm were compared with separation factors reported for two of the best liquid-liquid extractants viz. di-2-ethylhexyl phosphoric acid and 2-ethylhexyl-ethylhexyl phosphate.