A novel functionalized nanoporous SBA-15 as a selective fluorescent sensor for the detection of multianalytes (Fe3+ and Cr2O72−) in water

A novel silica-based chemosensor (SBA-Is-INH) was prepared through the functionalization of mesoporous silica SBA-15 material with a fluorescent chromophore, (Z)-N'-(2-oxoindolin-3-ylidene)isonicotinohydrazide. The synthesized materials were characterized by different techniques such as low angle XRD, N2 adsorption-desorption, TGA, TEM and FT-IR spectroscopy. The data showed that the organic moiety (0.41 mmol g−1) was successfully grafted to the SBA-15 and the primary hexagonally ordered mesoporous structure of SBA-15 was preserved after the grafting procedure. Photoluminescence spectroscopy has been used to investigate the sensing behavior of this material. SBA-Is-INH showed high selectivity for Fe3+ and Cr2O72− in water over a wide range of tested ions. Upon introducing trace amounts of Fe3+ and Cr2O72− ions into aqueous solution, remarkable quenching in the fluorescence was observed. Furthermore, a good linearity was observed between the fluorescence intensity of SBA-Is-INH and the concentration of Fe3+ and Cr2O72− with satisfactory detection limits of 6.04×10−7 M and 5.09×10−7 M, respectively. Finally, the proposed method was successfully utilized for the determination of Fe3+ and Cr2O72− in river water, well water and tap water samples.