MODIFICATION OF CARBON PASTE ELECTRODE BY Fe3O4/ZnO NANOCOMPOSITE FOR ANODIC STRIPPING VOLTAMMETRIC DETERMINATION OF Cd AND Pb IONS

Abstract

Fe3O4, ZnO and Fe3O4/ZnO nanomaterials were synthesized successfully using by co- precipitation method from FeCl3. 6H2O, FeCl2.4H2O and Zn(NO3)2. 6H2HO precursor salts. The structural, functional group and optical properties of the nanomaterials were characterized by employing XRD, FTIR and UV-Vis spectroscopy. The electrochemical properties of carbon paste electrode (CPE) modified by Fe3O4, ZnO and Fe3O4/ZnO were studied using cyclic voltammetry (CV) in the presence of 5mM K3Fe(CN)6 and 0.1 M KCL. The results of CV demonstrated a quasi reversible process and the Fe3O4/ZnO/CPE showed higher peak current and higher surface area comparable with single modified nanoparticles due to synergetic effect. At optimal condition pH4.5, concentration 400 ppm deposition time 90 s and appropriate deposition potential, the electrodes exhibited the linear range between 100 to 800 ppm before the detection of Pb and Cd ions using anodic stripping voltammetry (ASV). Furthermore, Fe3O4/ ZnO/CPE sensor was shown a good sensitivity and selectivity for the determination of Pb and Cd ions. The detection limit of Pb and Cd ions were 0.29 and 0.17 µg/L and their sensitivity 4.32 and 3.9 µAMcm -2 for Pb and Cd respectively. The concentrations of metal ions in effluent water collected from Haramaya University were Pb 0.0016 and Cd 0.0015 mg/L. The levels of Pb and Cd ions were less than the permissible value recommended by WHO, 2008. Therefore, this finding indicated that the carbon paste electrode modified by Fe3O4/ZnO can be a good candidate for determination of Pb(II) and Cd(II) and other heavy metals.