Bentonite Modified Carbon Paste Electrode as a Selective Electrochemical Sensor for the Detection of Cadmium and Lead in Aqueous Solution

Abstract

This work describes the use of a carbon paste electrode (CPE) modified with a Bentonite clay (Maghnite) as an electrochemical non-pollutant, selective and low cost sensor for Cadmium and Lead detection in aqueous solution. The physico-chemical properties of the clay mineral were analysed by X-Ray Fluorescence analysis (XRF), Powder X-ray diffraction (XRD), Thermogravimetric analysis (TG) and N2 adsorption isotherm. The square wave anodic stripping voltammetry (SWASV) has been used in which the different electrochemical parameters have been studied. The optimal preconcentration pH and Maghnite-CPE content were found to be 3.4 and 14% w/w respectively. Under these optimized conditions and at a preconcentration time of 5 min, the response of the electrode was linear with analytes concentration in the ranges from 1 to 30 µmol/L for Cadmium and 0.1 to 30 µmol/L for Lead with limit of detection (LOD) values of 0.16 µmol/L and 0.30 µmol/L for Cadmium and Lead respectively.