Sensing and magnetic removal of Hg(II) using core–shell structured nanocomposite grafted with fluorescence “Off–On” probe

•Core–shell structured nanocomposite was made for Hg(II) sensing and removal.•Inner core was composed of superparamagnetic Fe3O4 nanoparticles.•Silica molecular sieve shell was grafted by rhodamine derived probe.•Emission “Off–On” effect towards Hg(II) with good selectivity was observed.

This paper reported the preparation, characterization, Hg(II) sensing and removal performance of a core–shell structured nanocomposite grafted with rhodamine derived probe. The inner core was composed of superparamagnetic Fe3O4 nanoparticles and responsible for magnetic removal. The outer shell was composed of silica molecular sieve MCM-41 having large surface area and highly ordered tunnels. The Hg(II) sensing probe was derived from rhodamine 6G which showed emission “Off–On” effect towards Hg(II), owing to structural transformation from a non-emissive one to a highly emissive one. The nanocomposite was fully characterized by electron microscopy images, XRD analysis, thermogravimetric analysis and N2 adsorption/desorption isotherms. It was found that nanocomposite emission increased with increasing Hg(II) concentrations, showing emission “Off–On” effect. In addition, this nanocomposite owned high selectivity and fast response towards Hg(II) owing to its large surface area and highly ordered tunnels.

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