Nickel(II)‐imprinted monolithic columns for selective nickel recognition

Ni 2+ ‐imprinted monolithic column was prepared for the removal of nickel ions from aqueous solutions. N ‐Methacryloyl‐ L ‐histidine was used as a complexing monomer for Ni 2+ ions in the preparation of the Ni 2+ ‐imprinted monolithic column. The Ni 2+ ‐imprinted poly(hydroxyethyl methacrylate‐ N ‐methacryloyl‐ L ‐histidine) (PHEMAH) monolithic column was synthesized by bulk polymerization. The template ion (Ni 2+ ) was removed with a 4‐(2‐pyridylazo) resorcinol (PAR):NH 3 NH 4 Cl solution. The water‐uptake ratio of the PHEMAH–Ni 2+ monolith increased compared with PHEMAH because of the formation of nickel‐ion cavities in the polymer structure. The adsorption of Ni 2+ ions on both the PHEMAH–Ni 2+ and PHEMAH monoliths were studied. The maximum adsorption capacity was 0.211 mg/g for the PHEMAH–Ni 2+ monolith. Fe 3+ , Cu 2+ , and Zn 2+ ions were used as competitive species in the selectivity experiments. The PHEMAH–Ni 2+ monolithic column was 268.8, 25.5, and 10.4 times more selective than the PHEMAH monolithic column for the Zn 2+ , Cu 2+ , and Fe 3+ ions, respectively. The PHEMAH–Ni 2+ monolithic column could be used repeatedly without a decrease in the Ni 2+ adsorption capacity. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010