Determination of heavy metals by bismuth-carbon nanotube modified electrodes

Abstract

In this research, the bismuth–carbon nanotube (Bi–CNT) composites were synthesized by polyol process and have been developed as working electrodes for the determination of cadmium (II) and lead (II) ions by means of square wave anodic stripping voltammetry. Prepared Bi–CNT composites were characterized by X-ray diffraction (XRD) technique, transmission electron microscopy (TEM), and energy dispersive X-ray fluorescence (EDXRF) spectroscopy. Bi–CNT/GC electrode exhibited well-defined and sharp stripping signals for both metal ions and a reproducibility of 2.44% and 3.19% (n = 8) for 25 μg·L–1 cadmium (II) and lead (II) ions, respectively. In addition, the modified electrode displayed excellent linear behavior in two concentration ranges: 5 to 150 μg·L–1 and 150 to 240 μg·L–1. At the lower concentration range, the correlation coefficients (R2) were 0.9986 for cadmium (II) ion and 0.9990 for lead (II) ion. For the calibration curve from 150 to 240 μg·L–1, the R2 of 0.9983 and 0.9970 was obtained for cadmium (II) and lead (II) ions. Under optimal conditions, the Bi–CNT/GC electrode displayed more attractive voltammetric responses than in situ bismuth film on CNT modified glassy carbon (in situ BiF/CNT/GC) electrode. Finally, the developed electrode was applied to tap water and waste water samples for the analysis of cadmium (II) and lead (II) ions with satisfactory results.