Benzimidazolium\nSalt Modified Microporous Silica-Coupled\nIron Oxide Nanoparticles: Material Engineered for Nitrate Removal

Today’s\nextensive use of inorganic fertilizers in agricultural\ntechniques has increased the concentration of nitrate in drinking\nwater beyond safety limits, causing serious health problems in humans\nsuch as thyroidism and methemoglobinemia. Therefore, the present work\ndescribes the synthesis of a benzimidazolium salt-based fluorescent\nchemosensor (KG3) via a multistep synthesis which detects nitrate\nions in aqueous medium. This was validated using various analytical\ntechniques such as fluorescence spectroscopy, UV–visible spectroscopy,\nand electrochemical studies with a detection limit of 0.032 μM\nwithout any interference from other active water pollutants. Subsequently,\nKG3 is further modified with the help of iron oxide nanoparticles\n(Fe<sub>3</sub>O<sub>4</sub> NPs) and silica to obtain the SiO<sub>2</sub>@Fe<sub>3</sub>O<sub>4</sub>-KG3 nanocomposite, which was\nimmobilized over a polyether sulfone membrane and evaluated for removal\nof nitrate ions from groundwater with a removal efficiency of 96%.\nMoreover, the engineered composite membrane can serve as a solid-state\nfluorescence sensor to detect NO<sub>3</sub><sup>–</sup> ions,\nwhich was demonstrated through a portable mobile-based prototype employing\na hue, saturation, and value parameter model.