Rhodamine functionalized magnetic core–shell nanocomposite: An emission “Off–On” sensing system for mercury ion detection and extraction

• An optical sensing system for Hg(II) detection and extraction was constructed.
• It consisted of Fe3O4 based core and silica molecular sieve based shell.
• A rhodamine derived probe was grafted into the silica shell.
• Emission “Off–On” effect and linear response were observed from the composite.

This paper reported a core–shell structured composite with superparamagnetic ferroferric oxide as the inner core and silica molecular sieve as the outer shell. A rhodamine based sensing dye was covalently grafted into the highly ordered tunnels of silica molecular sieve, so that mercury ion sensing and extraction could be achieved from this composite. This probe loaded core–shell structure was characterized by electron microscopy images, X-ray diffraction patterns, infrared spectra, thermogravimetry and N2 adsorption/desorption measurement. This composite showed increased emission with increasing mercury ion concentration, along with high sensitivity and good selectivity. Linear response and good regenerating performance were also observed from this composite.

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