Effective and selective removal of heavy metals from industrial effluents using sustainable Si-CD conjugate based column chromatography

The present investigation deals with the green synthesis of aqueous-stable and highly fluorescent carbon dots (CD) by hydrothermal treatment of tender leaf extract of Ficus benghalensis. The synthesized CD was characterized. Carbon dots were of an average size of 2.28 nm with a blue-green fluorescence emission at 317 nm and showed high selectivity and specificity for iron and nickel amongst the different tested heavy metals with a LOD of 0.0015 mu mol/mL and 0.000014 mu mol/mL respectively. Further, we functionalized silica with the prepared carbon dot to generate an adsorbent for purification of contaminated water. A short bed adsorbed column system was designed for determining the efficiency of adsorption. As envisioned approximately, 77% and 74% removal of Fe and Ni was observed when the metal salts were eluted individually. Purification efficacy was analysed using an industrial electroplating effluent, which showed adsorption of 74% and 79% for Fe and Ni respectively.