Dual Functions of Selective Ferric Ion Detection and Removal by a Recyclable Fluorescence Active Multifunctional Silica Material and Toxic Dye Removal from Aqueous Solution

Abstract

Excess iron and its toxic dye Naphthol Green B is a threat to aquatic environment and human health. Therefore, effective detection and remediation of ferric ion and Naphthol Green B in aqueous system is a necessity. In our paper, to bring out synergy in dual functions of ferric ion sensing and extraction/removal by same material, a new ionophore based functionalized silica material (SiO2@Nap) was synthesized by immobilization of bis (tetradentate) naphthalene ligand on silica surface. Physicochemical properties of the adsorbent were studied by scanning and transmission electron microscopy, atomic force microscopy, XRD, FT-IR, thermo-gravimetric analysis and elemental (CHN) analysis. The selective sensing studies by SiO2@Nap material towards ferric ion in presence of 17 other relevant metal ions were evaluated through the fluorescence quenching phenomenon which gives limit of detection value of 74 ppb (1.31 μM). The adsorption studies for ferric ion were assessed in view of effect of solution pH, extraction efficiency (99%), adsorption capacity (79 mg/g) and adsorption isotherms. This material can be recycled upon simple acid-base treatments for further usage after recovery of ferric ions which is supported by reversibility studies. The strong affinity towards ferric ion enabled this material to remove iron containing industrial toxic dye Naphthol Green B with 99.5% efficiency with recyclability. Adsorption, striping and regeneration studies reveals that SiO2@Nap is a recyclable extracting cum sensory probe material for ferric ions.