Electrochemical determination of traces lead ions using a new nanocomposite of polypyrrole/carbon nanofibers

In this paper, a new nanocomposite of polypyrrole (PPy) and carbon nanofibers (CNFs)-modified carbon paste electrode (CPE) has been reported for the determination of traces lead ions (Pb2+). The obtained nanocomposite was fabricated by combining the unique advantages of PPy and CNFs using a very simple approach, which consists on modifying the CPE by the functionalized CNFs and then by the PPy film using galvanostatic mode. Several techniques were used to investigate the functionalized CNFs and the PPy/CNFs nanocomposite including Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) for surface layers of CNFs, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) for the electrical proprieties of the PPy/CNFs nanocomposite. The surface morphologies were examined by field-emission gun scanning electron microscopy (FEG-SEM). The square wave anodic striping voltammetry (SWASV) was used to investigate the analytical performances of the designed electrode PPy/CNFs/CPE. Different parameters that affect the stripping analysis of Pb2+ including supporting electrolyte, deposition potential, and deposition time were investigated. Under the optimum experimental conditions, a good linearity between the stripping peak currents and the concentration of Pb2+ was obtained in the range of concentration from 0.2 to 130 mu g L-1 Pb2+. The detection limit was estimated to be 0.05 mu g L-1 Pb2+. Finally, the proposed method has been successfully applied for the determination of Pb2+ in real samples of tap water with satisfactory results.