Sensitive voltammetric determination of cadmium at a carbon nanotubes/Fe3O4/eggshell composites modified carbon paste electrode

Abstract

In the present work, we describe a new method for differential-pulse anodic stripping voltammetric (DPASV) determination of cadmium (II) using a carbon paste electrode modified with magnetic nanocomposite of Fe3O4/eggshell and carbon nanotubes (MWCNT-MES-CPE). In addition to Fourier transform infrared spectroscopy (FT-IR) and vibrating sample magnetometer (VSM) for the characterization of the prepared magnetic nanocomposite, the morphology and structure of Fe3O4/eggshell were studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effective experimental parameters on the preconcentration of Cd (II) ions and voltammetric stripping step such as supporting electrolyte (type and concentration), accumulation and reduction potential, and of time and amount of modifier were investigated by differential pulse anodic stripping voltammetry. The voltammetric peak current of Cd (II) appeared at a potential about −0.7 V, under optimum conditions. The method was then worked out for the determination of cadmium at low levels. Under optimized conditions, the response to Cd (II) is linear in the range from 3.0 to 250 ng mL−1 with a detection limit of 2.4 ng mL−1 for Cd (II) ion. The sensor was applied to the determination of Cd (II) in water, hair samples, and certified reference materials.