SYNTHESIS AND CHARACTERIZATION OF PANI/ZnO BASED ELECTROCHEMICAL SENSOR FOR THE DETECTION OF SOME TOXIC HEAVY METAL IONS

Abstract

A polyaniline/Zinc oxide (PANI/ZnO) nanocomposites based electrochemical sensor was Prepared by electropolymerization of ananiline monomer on a Zinc oxide film modified glassy carbon electrode (ZnO/GCE) at different film thickness to form PANI/ZnO/GCE. The electrochemical behaviour of the PANI film on bare and ZnO modified GCE was characterized by cyclic voltametry(CV) in monomer free 1.0 M HCl(aq) and EIS. CV of PANI on bare and ZnO modified glassy carbon electrode revealed two anodic and cathodic peaks. For comparison PANI and PANI/ZnO nanocomposites were also prepared chemically by employing in-situ oxidation polymerization method and characterized by Uv vis, FT-IR, HRSEM and HR-TEM. Similarily, chemically produced nanomaterials characterized electrochemically showed two anodic and two cathodic peaks by CV in monomer free 1.0 M HCl(aq). The PANI/ZnO/GC electrode was employed as sensor for the detection of toxic heavy metal ions in water samples using Ostroyoung square wave anodic stripping voltammetry (OSW ASV). The results indicated that the PANI-ZnO/GCE sensor was more sensitive (with a dynamic linear range of 5.0 to 25.0 ppb and a detection limit (LOD) of 2.8, 1.84, 0.21 and 0.84 ppb for Cd(II), Pb(II), As(III) and Hg(II), respectively) than PANI/GCE and/or GCE. PANI-ZnO/GCE as sensor exhibited lower detection limits than the WHO permissible level of 5, 5, 10 and 5 µgL-1 for Cd(II), Pb(II), As(III) and Hg(II), respectively in water. All the detections were performed under optimized experimental conditions.