Preparation of Poly(1-vinylimidazole)-Grafted Magnetic Nanoparticles and Their Application for Removal of Metal Ions

Poly(1-vinylimidazole) with a trimethoxysilyl terminal group (Im n ) was synthesized by telomerization of 1-vinylimidazole. The degree of polymerization ( n ) was determined by 1 H NMR to be 18. The Im 18 with reactive silane terminal group was grafted directly onto nanosize magnetic particles (maghemite, γ-Fe 2 O 3 ) through siloxane bonds to produce polymer-grafted magnetic nanocomposite particles (Mag-Im 18 ). The amount of polymer anchored on the particle was estimated by elemental analysis to be 5 wt %. The surface coverage of imidazolyl groups was estimated to be 0.44 mmol g - 1 . A stable Mag-Im 18 suspension was prepared, and the polymer coatings were chemically stable over a pH range of 3.5−10.0. The Mag-Im 18 showed a selective binding of divalent metal ions with a binding strength in the order of Cu 2+ ≫ Ni 2+ > Co 2+ . At pH 5.3, the limiting adsorption capacity for Cu 2+ ion was 0.11 mmol g - 1 . Selective separation/recovery of Cu 2+ ions from a Cu 2+ /Co 2+ aqueous solution was demonstrated over a pH range of 3−7.