Simultaneous electrochemical sensing of Pb2+ and Hg2+ in aqueous media using 5-amino-1,3,4-thiadiazole-2-thiol functionalized mesoporous silica

Abstract

Metal ion pollution is a major environmental concern with toxic metals like lead (Pb) and mercury (Hg) contaminating water, soil and air which pose serious risks to human health and the ecosystem. Thus, effective monitoring is essential to assess and mitigate their harmful impact. Electrochemical metal ion sensing has emerged as a promising real-time technique for quantifying metal ions through electrode reactions with high accuracy, sensitivity and selectivity. For this purpose, a thiol-functionalized silica supported material, FMS-TA-ATT, has been synthesized for the electrochemical sensing of Pb2+ and Hg2+ simultaneously and individually in 0.2 M acetate buffer solution, and is found to hold promising detection ability in neutral medium (pH = 7). The comprehensive characterization of the synthesized materials has been done by powder X-ray diffraction, electronic microscopy, nitrogen adsorption/desorption studies, thermogravimetric analysis, FT-IR, solid state 29Si and 13C CP MAS NMR spectroscopy and the electrochemical behavior has been evaluated by cyclic voltammetry and electrochemical impedance spectroscopy. The sensing ability of the glassy carbon electrode prepared with FMS-TA-ATT (FMS-TA-ATT/GCE) has been examined by differential pulse voltammetry. This material shows a good selectivity and sensitivity towards Pb2+ and Hg2+ in 0.2 M acetate buffer solution at pH = 7 with very low limit of detection (LOD) (13 nM for Pb2+ and 29 nM for Hg2+). Additionally, FMS-TA-ATT/GCE is efficient to detect Pb2+ and Hg2+ in the presence of other metal ions and it also displays sensing ability with real water samples.