Organic-inorganic hybrid fluorescent sensor thin films of rhodamine B embedded Ag-SBA 15 for selective recognition of Hg (Ⅱ) ions in water

Nowadays, the rapid and effective detection of low doses of heavy metal pollutants in contaminated water is a timely challenge in environmental pollution research. In this study, a rapid and highly sensitive assay for the detection of Hg~(2+)based on quenching of metal-enhanced fluorescence of rhodamine B(RB)has been fabricated. RB and silver nanoparticle were incorporated into the mesoporous siliceous framework spin cast on a quartz glass through post-synthetic incorporation method. The morphology and crystallinity of mesoporous structure and Ag nanoparticle were characterized by transmission electron microscopy and X-ray diffraction analyses. Photoluminescence assays on the hybrid thin film of RB-Ag-SBA15 showed a high enhancement when compared to the intensity of silver free SBA15-RB in the wavelength of 575 nm. The fluorescence of RB-Ag-SBA15 thin film decreased gradually with the increase in the concentration of Hg~(2+)and the detection limits were 10.54 nmol/L. Furthermore, the fluorescence intensity increased linearly with the concentration of Hg~(2+)in the range from 1.0 ? 10à8mol/L to10 ? 10à8mol/L, with a response time of a few seconds. In addition, this system offers a high selectivity over interfering cations such as Cd~(2+) and Pb~(2+). Overall, we have developed an optical assay having a wellordered mesoporous SBA15 containing Ag-RBfor selective detection of Hg~(2+)in aqueous solution. The scheme combines the advantages of specific binding interactions between Hg~(2+)and RB molecule and optical emission properties of RB. The method is suitable for a single-shot and irreversible analytical assay in a quartz glass/microtiter plate.