Simultaneous Determination of Hg(II), Cd(II), Pb(II) and Zn(II) by Anodic Stripping Voltammetry using Modified Carbon Paste Ionic Liquid Electrode

In the presented study, CuO-CoO-MnO/SiO2 nanocomposite was synthesis by Cu(II), Co(II), Mn(II), with 1:1:1 mole ratio and Tetraethyl orthosilicate. azo–azomethine 1-(3-imino-4-hydroxophenylazo-4-nitrobenzene)-4-methyl phenol (L) was synthesized and used as a ligand for capturing the metal ions. Also, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide was applied as the ionic liquid in order to increase the conductivity of the electrode. The nanomaterials were investigated using Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM); SEM image shows a homogeneous CuO-CoO-MnO/SiO2 nanocomposite, with an average particle size distribution of 40 nm. Also, the electrochemical characterization of L/CuO-CoO-MnO/SiO2/IL/CPE was checked by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques. The modification of carbon paste electrode applied to determination of some heavy metal ions include Hg(II), Cd(II), Pb(II) and Zn(II) by square wave anodic stripping voltammetry (SWASV), for the first time. The linear range for determination of analytes in optimized condition was obtained as Hg: 0.0007-0.21 and 0.21-27 μM, Cd: 0.0007-0.21 and 0.21-27 μM, Pb: 0.0009-0.23 and 0.23-27 μM, Zn: 0.001-0.25 and 0.25-27 μM. Also, the detection limits for Hg(II), Cd(II), Pb(II) and Zn(II) were calculated to be 3.019×10-4, 3.445×10-4, 2.407×10-4 and 5.134×10-4 μM, respectively. Finally, the sensor was successfully used for the measurement of the analytes in Tap water and River water samples with recoveries ranging between 98.1% and 102.7%. Also, the obtained results accorded very well with those obtained by atomic absorption spectroscopy (AAS) that corroborated the accuracy and validity of the proposed method.