Three-dimensional wormhole mesoporous-based material as a regenerative solid optical sensor for detection of Hg2+ in aqueous media

With the aim of optical sensing of Hg2+ in water, a new optical sensor (RhB-HMS) for detecting Hg2+ has been successfully prepared by immobilizing a Rhodamine B (RhB) derivative on hexagonal mesoporous silica (HMS) via triethoxysilane groups. The transmission electron microscopy (TEM) images and X-ray powder diffraction (XRD) data of RhB-HMS confirm that the worm-like mesoporous structure is preserved during the post-grafting procedure. The nitrogen adsorption-desorption isotherms and Fourier transform infrared (FT-IR) spectroscopy results show that the grafting of the RhB derivative onto HMS is successful. A detailed study of the fluorescence properties of RhB-HMS is reported. RhB-HMS affords "turn-on" fluorescence enhancement and displays high brightness in water. In addition, RhB-HMS is able to react with Hg2+ between pH 5.2 and 8.3 and offer a high selectivity over several interfering cations (K+, Na+, Li+, Ag+, Cd2+, Ca2+, Co2+, Cu2+, Ni2+, Mg2+, Pb2+ and Fe2+). More importantly, RhB-HMS shows excellent reversible and regenerative ability to detect Hg2+ by the naked-eye.