Green synthesis and spectroscopic studies of ag-rGO nanocomposites for highly selective mercury (II) sensing

Introduction: Herein we report the green synthesis and characterization of silver-reduced graphene oxide nanocomposites (Ag-rGO) using Acacia nilotica gum for the first time. Experimental: We demonstrate the Hg ²⁺ ions sensing ability of the Ag-rGO nanocomposites form aqueous medium. The developed colorimetric sensor method is simple, fast and selective for the detection of Hg ²⁺ ions in aqueous media in presence of other associated ions. A significant color change was noticed with naked eye upon Hg ²⁺ addition. The color change was not observed for cations including Sr ²⁺ , Ni ²⁺ , Cd ²⁺ , Pb ²⁺ , Mg ²⁺ , Ca ²⁺ , Fe ²⁺ , Ba ²⁺ and Mn ²⁺ indicating that only Hg ²⁺ shows a strong interaction with Ag-rGO nanocomposites. Under the most suitable condition, the calibration plot (A ₀ -A) against concentration of Hg ²⁺ was linear in the range of 0.1-1.0 ppm with a correlation coefficient (R ² ) value 0.9998. Results & Conclusion: The concentration of Hg ²⁺ was quantitatively determined with the Limit of Detection (LOD) of 0.85 ppm. Also, this method shows excellent selectivity towards Hg ²⁺ over nine other cations tested. Moreover, the method offers a new cost effective, rapid and simple approach for the detection of Hg ²⁺ in water samples.