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 1H NMR to be 18. The Im18 with reactive silane terminal group was grafted directly onto nanosize magnetic particles (maghemite, γ-Fe2O3) through siloxane bonds to produce polymer-grafted magnetic nanocomposite particles (Mag-Im18). 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-Im18 suspension was prepared, and the polymer coatings were chemically stable over a pH range of 3.5−10.0. The Mag-Im18 showed a selective binding of divalent metal ions with a binding strength in the order of Cu2+ ≫ Ni2+ > Co2+. At pH 5.3, the limiting adsorption capacity for Cu2+ ion was 0.11 mmol g-1. Selective separation/recovery of Cu2+ ions from a Cu2+/Co2+ aqueous solution was demonstrated over a pH range of 3−7.