Fabrication of carbon nanotube and synthesized Octadentate ligand modified electrode for determination of Hg (II) in Sea water and Lake water using square wave anodic stripping voltammetry

Based on carbon nanotubes and N,N',N '',N'''-Tetrasalicylidene-3,3'-diaminobenzidine (H4tsdb) modified electrode, the determination of Hg (II) ion using square wave anodic stripping voltammetry (SWASV) is reported. The N,N',N '',N'''-Tetrasalicylidene-3,3'-diaminobenzidine (Octadentate ligand) has been derived from the condensation of Salicylaldehyde and 3'3-diaminobenzidine. The ligand has been characterized by Ultraviolet-Visible spectroscopy (UV-VIS), Fourier transform infrared spectroscopy (FT-IR) and Proton-Nuclear magnetic resonance (H1-NMR) spectroscopy. The surface morphology of the fabricated electrode has been characterized by scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS). Operational parameters such as preconcentration, pH, supporting electrolytes were optimized for the determination of mercury (II) in 0.1M NaNO3 pH 5. Under optimized condition, the electrochemical sensor exhibited a wider linear range from 2.4-220 nM and the limit of detection was 0.8 nM for Hg (II) (S/N <= 3). The relative standard deviation (RSD) was found to be 3.0% for five successive determinations. Interferences studies from other heavy metal ions such as Mn(II), Cd(II), Pb(II), Ni(II), Cu(II) and Zn(II) showed an insignificant effect on the electrochemical response of Hg(II) ion. The proposed electrode exhibited excellent performance in reproducibility, selectivity and also for successfully applied to analysis of Hg(II) in real environmental samples.