Preparation of optical nano sensor for rapid detection of Fe(III) using phenyl isothiocyanate functionalized SBA-15

The present study focuses on the synthesis of a mesoporous silica compound functionalized with phenyl isothiocyanate (SBA-15-PITC) for the development of an optical fluorescent sensor with the aim of detecting Fe(III) ions. The final product was synthesized through a sequential process involving the synthesis of SBA-15-Cl, followed by functionalization with tris(2-aminoethyl)amine and phenyl isothiocyanate. X-ray diffraction (XRD) analysis confirmed the hexagonal symmetry of the mesoporous silica structure. Fourier-transform infrared spectroscopy (FT-IR) spectra demonstrated the successful grafting of phenyl isothiocyanate onto the surface of SBA-15. The functionalized product exhibited a Brunauer–Emmett–Teller surface area of 745 mg and a pore diameter of 6.7 nm as determined by N adsorption–desorption isotherms. Transmission electron microscopy and scanning electron microscopy images depicted well-ordered arrays of channels with rope-shaped morphology for SBA-15-PITC. Subsequently, the capability of SBA-15-PITC for metal cation sensing was evaluated based on its fluorescence properties. SBA-15-PITC exhibited two distinct fluorescence peaks at approximately 410 nm and 372 nm, which experienced a significant decrease upon adding Fe(III) ions. Quantitative detection of Fe(III) was achieved at a wavelength of 410 nm within a broad working range of 5.96 × 10 to 2.76 × 10 M, as well as at a wavelength of 372 nm within a working range of 1.99 × 10 to 1.54 × 10 M. The results indicated less than 5% fluctuations in fluorescence intensity during the initial 5 min. Overall, the experimental findings underscore the efficacy of this optical sensor for the rapid and sensitive detection of Fe(III) across a relatively extensive concentration range in both water and food samples. Graphical Abstract: (Figure presented.)