A multifunctional magnetic core–shell fibrous silica sensing probe for highly sensitive detection and removal of Zn2+ from aqueous solution

Abstract

In the present work, a multifunctional core–shell magnetic fibrous silica sensing probe AQ-Fe₃O₄@SiO₂@KCC-1 was prepared for the detection, adsorption and removal of Zn²⁺. The core was composed of superparamagnetic Fe₃O₄ nanodots, while the shell consisted of fibrous silica molecular sieve KCC-1 and was decorated by a quinoline derived probe. The multifunctional inorganic–organic hybrid material was characterized by transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, N₂ adsorption–desorption, thermogravimetric analysis, and vibrating sample magnetometry. Its sensing performance towards Zn²⁺ was then discussed in detail. The experimental results suggested that this functional material exhibited enhanced fluorescence in the presence of Zn²⁺ ions and a high selectivity for Zn²⁺ over the competing metal ions in aqueous solution. The binding ratio of the AQ-Fe₃O₄@SiO₂@KCC-1–Zn²⁺ complexes was determined from the Job plot to be 1 : 1. The association constant was calculated to be 1.85 × 10⁵ M⁻¹, with a detection limit of 1.08 × 10⁻⁷ M. Furthermore, the adsorption process of Zn²⁺ on the magnetic fibrous silica composite AQ-Fe₃O₄@SiO₂@KCC-1 was well described by the Langmuir isotherm equation and the equilibrium adsorption capacity is 157.2327 mg g⁻¹. These results indicate that these multifunctional magnetic fibrous silica sensing materials may find potential and favorable applications for simple detection and efficient removal of Zn²⁺ in toxicological and environmental fields.