A chromotropic acid modified SBA-15 as a highly sensitive fluorescent probe for determination of Fe3+ and I− ions in water

Abstract

A novel organic–inorganic hybrid nanomaterial (SBA-15-CA) was prepared by covalent immobilization of chromotropic acid onto the surface of mesoporous silica material SBA-15. Different techniques such as XRD, TEM, FT-IR, N2 adsorption–desorption and TGA analyses were employed to characterize the grafting process. 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. SBA-15-CA has been realized as a highly sensitive and selective fluorescent probe towards Fe3+ and I− ions in aqueous media. SBA-15-CA exhibited a remarkable fluorescent quenching in the presence of Fe3+ ion over other competitive cations including Na+, Mg2+, Al3+, K+, Ca2+, Cr3+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+, and Pb2+ as well as I− ion among a series of anions including F−, Cl−, Br−, CO32−, HCO3−, CN−, NO3−, NO2−, SCN−, SO42−, H2PO4−, HPO42−, and CH3COO−. A good linear response was observed between the concentration of the quenchers (Fe3+ and I− ions) and fluorescence intensity of SBA-15-CA with detection limits of 1.5 × 10−7 M for Fe3+ and 0.2 × 10−7 M for I−. Moreover, the effects of various pH values on the sensing ability of SBA-15-CA were investigated. Finally, the proposed method was successfully utilized for the determination of Fe3+ and I− ions in river water, well water and tap water samples.