A Nanosensor for Naked-Eye Identification and Adsorption of Cadmium Ion Based on Core–Shell Magnetic Nanospheres

Fe(3)O(4)@SiO(2) nanospheres with a core–shell structure were synthesized and functionalized with bis(2-pyridylmethyl)amine (BPMA). The photoresponses of the as-obtained Fe(3)O(4)@SiO(2)-BPMA for Cr(3+), Cd(2+), Hg(2+) and Pb(2+) ions were evaluated through irradiation with a 352 nm ultraviolet lamp, and Fe(3)O(4)@SiO(2)-BPMA exhibited remarkable fluorescence enhancement toward the Cd(2+) ion. The adsorption experiments revealed that Fe(3)O(4)@SiO(2)-BPMA had rapid and effective adsorption toward the Cd(2+) ion. The adsorption reaction was mostly complete within 30 min, the adsorption efficiency reached 99.3%, and the saturated adsorption amount was 342.5 mg/g based on Langmuir linear fitting. Moreover, Fe(3)O(4)@SiO(2)-BPMA displayed superparamagnetic properties with the saturated magnetization of 20.1 emu/g, and its strong magnetic sensitivity made separation simple and feasible. Our efforts in this work provide a potential magnetic functionalized nanosensor for naked-eye identification and adsorption toward the Cd(2+) ion.