Selective Adsorption of Uranium (VI) on NaHCO₃ Leached Composite γ Methacryloxypropyltrimethoxysilane Coated Magnetic Ion-imprinted Polymers Prepared by Precipitation Polymerization

Abstract

Ion imprinted nano-magnetic composite polymers for selective removal of hexavalent uranium were prepared by a precipitation polymerization technique in the presence of γ-methacryloxypropyltrimethoxysilane (γ-MPS) coated magnetite and other pre-polymerization reagents. The synthesized magnetic polymers were then leached with NaHCO₃ to produce magnetic ion imprinted polymers (IIPs) with fabricated adsorption sites complementary to the uranyl ions in terms of size and shape. Several parameters were investigated to obtain conditions which gave the optimum adsorption of the uranyl onto the magnetic IIPs and their corresponding controls, magnetic ion non-imprinted polymers (NIPs). The optimum amount of magnetic sorbent, initial concentration and contact time were 50 mg, 2.5 mg L^–1 and 45 min, respectively. The adsorption capacity of the magnetic IIP (1.15 ± 0.01 mg g^–1) was higher than that of the magnetic NIP (0.93 ± 0.02 mg g^–1). This indicated that the former had a somewhat higher affinity for U(VI) than the later. The magnetic polymers also displayed good selectivity of the order: U(VI) > Ni(II) > Mg(II). After six cycles of use, the magnetic polymers illustrated good stability and reusability.

KEYWORDS Complex matrices, magnetic ion imprinted polymers, precipitation, selectivity, uranium.