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

Poly(1-vinylimidazole) with a trimethoxysilyl terminal group (Imn) was synthesized by telomerization of 1vinylimidazole. 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, -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.