Selective recognition of neodymium (III) using ion imprinted polymer particles

Abstract

Neodymium (III) ion-imprinted polymer (IIP) materials were prepared by the copolymerization of neodymium (III)-5,7-dichloroquinoline-8-ol-4-vinylpyridine ternary complex with styrene(monomer), divinyl benzene (crosslinking monomer) in the presence of 2,2'-azobisisobutyronitrile (initiator). The synthesis was carried out in 2-methoxy ethanol medium (porogen) and the resultant material was filtered, washed, dried and powdered to form unleached IIP particles. The imprint ion was removed by stirring the above particles with 50% (v/v) HCl for 6 h to obtain leached IIP particles with cavities in the polymer particles. Control polymer (CP) particles were similarly prepared without imprint ion, i.e. neodymium (III). CP, unleached and leached IIP particles were characterized by TLC, IR, microanalysis, XRD and UV-visible spectrophotometric studies. The preconcentration of 5-150 microg of neodymium (III) ions present in 500 ml of solution was possible with as little as 40 mg of neodymium (III) IIP particles in the pH range 7.5-8.0 with a detection limit of 50 ng/l. Five replicate determinations of 25 microg of neodymium (III) present in 500 ml of solution gave a mean absorbance of 0.120 with a relative standard deviation of 2.65%. The imprinting effect of IIP particles was noticed in all preconcentration and selectivity studies when compared with CP particles. Furthermore, the selectivity coefficients of neodymium (III) IIP particles were much higher compared with the reported separation factors for the best liquid-liquid extractants, viz. di-2-ethylhexyl phosphoric acid and 2-ethylhexyl-ethylhexyl phosphonate. Kinetic and isotherm studies during rebinding of neodymium (III) onto IIP particles were also carried out.

Ion imprinted polymer particles for separation of yttrium from selected lanthanides

“…The same authors reported a 2 -4-fold enhancement in selectivity coefficients by post-c-irradiation of dysprosium(III) IIP particles [10]. Selective recognition of neodymium(III) from La, Ce, Pr, Sm and Eu was achieved by using neodymium(III) IIP particles [11]. Kala et al [12 -14] reported higher selectivity coefficients for erbium over Y, Dy, Ho, Tb and Tm by employing erbium(III) IIP particles prepared by thermal, photochemical and c-irradiation polymerization methods over nonimprinted polymer particles.…”

Investigation of Sorption and Separation of Lanthanides on the Ion Exchangers of Various Types

“…More particularly in the case of ionic imprinting, the affinity partly depends on the number and the orientation of interaction points (ligand denticity) as well as on the counter ion. As described in the paper by (Krishna et al (2005) ion imprinting allows significant enhancement in selectivity coefficients of neodymium(III) with respect to La(III), Ce(III), Pr(III), Sm(III) and Eu(III). The obtained selectivity coefficients are several times higher than those for the best extractant such as D2EHPA, for example selectivity coefficient for Nd(III) over Ce(III) and Pr(III) increases twentyfold, threefold over La(III) and Sm(III).…”

Current status and challenges of ion imprinting

“…They synthesized IIP particles via a single pot reaction for separation of Y(III) from selected lanthanides, 233 and Er(III) IIP particles via thermally copolymerizing 234 and photochemical polymerization, 235 respectively. What's more, Nd(III) IIP materials 236 were prepared as well and also had good results. Guo et al 237 prepared Nd(III)-IIPs followed by ICP-AES determination with the largest selectivity coefficient, over 110, for Nd(III) in the presence of competitive ions such as La(III), Ce(III), Pr(III) and Sm(III).…”