ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Use of a Schiff base-modified conducting polymer electrode for electrochemical assay of Cd(II) and Pb(II) ions by square wave voltammetry

Mohammed Q. Mohammed, Hani K. Ismail, Hasan F. Alesary, and Stephen Barton

Department of Chemistry, College of Education for Pure Sciences, University of Basrah, Basrah, Iraq

E-mail: mahammed.qasim@uobasrah.edu.iq

Received: 26 March 2021  Accepted: 18 September 2021

Abstract:

The work herein describes the electrochemical detection of heavy metal ions, specifically cadmium and lead. The introduction and modification of functional groups such as Schiff bases leads to an enhanced sensitivity of the electrode to analytes. In this study, a platinum electrode has, for the first time, been modified with poly(3,4-ethylenedioxythiophene) (PEDOT/Schiff base) in CH₂Cl₂ containing Bu₄NPF₆ to detect cadmium(II) and lead(II) ions. The structures and morphologies of the polymer coatings were characterised via Fourier transform infrared spectroscopy and scanning electron microscopy, respectively. The electrochemical synthesis and redox state response in monomer-free synthesised films have been studied via cyclic voltammetry. Moreover, the effect of scan rate on the electrochemical behaviour of the modified electrodes was also studied. The voltammetric findings have been used to calculate the surface coverage required for the polymer films and the stability of polymer electrodes in the monomer-free solutions. Square wave voltammetry was applied for the determination of cadmium(II) and lead(II) ion concentrations and to assess the effects of pH on aqueous samples. The limits of detection for the modified electrode for cadmium(II) and lead(II) were found to be 0.95 μg L⁻¹ and 1.84 μg  L⁻¹, respectively. These findings revealed that modified films can be considered good candidates for application in electrochemical detection devices.

Keywords: Square wave voltammetry; Electrochemical detection; Conducting polymers; Modified electrode poly(3,4-ethylenedioxythiophene); Schiff base

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-021-01882-7

Chemical Papers 76 (2) 715–729 (2022)