Terbium Ion Adsorption from Aqueous Solution by Using Magnetic γFe2O3-NH4OH@SiO2 Nanoparticles Functionalized with Amino Groups

New magnetic stabilized and functionalized core@shell nanoparticles (NPs) were synthesized in a simple way and characterized in order to adsorb Tb3+ from aqueous solution with a very low Tb3+ concentration. For the fluorescence determination of adsorption efficiency and capacity, tiron monohydrate as a ligand was used. The obtained results confirm the potential of the synthesized magnetic γ-Fe2O3-NH4OH@SiO2 NPs, functionalized with (3-Aminopropyl) trimethoxysilane (APTMS), to be used for adsorption of Tb3+ from aqueous solution, with the possibility of its removal from aqueous solution via an external magnet. The endothermic and spontaneous adsorption follows a pseudo-second-order kinetic model, and the adsorption equilibrium data fit the Temkin isotherm well. The maximum adsorption efficiency from aqueous solution with a 2 × 10−6 M concentration of Tb3+ is over 90% at pH 7.