Using Electrode Made of Carbon Nanotubes and Bismuth Oxide for the Determination of Metal Concentration by Anodic Stripping Voltammetry

Abstract

We have successfully manufactured a new electrode modified with bismuth oxide (Bi2O3) using carbon nanotubes (CNTs). The electrode was fabricated to detect cadmium (Cd), lead (Pb), and indium (In) by differential pulse anodic stripping voltammetry (DP-ASV). The electrode surface was studied by scanning electron microscopy (SEM), and the reduction and oxidation processes were studied by cyclic voltammetry (CV) techniques. Operational parameters such as electrode size, bismuth concentration, and electrolytic background were optimized. The DP-ASV method used fabricated electrodes with a linear response range from 1.5–20 μg·L−1 with Cd(II) and Pb(II) and 2.5–20 μg·L−1 with In(III); low detection limit (LOD) of 0.22 μg·L−1 with Cd(II), 0.65 μg·L−1 with In(III), and 0.26 μg·L−1 with Pb(II); and good repeatability with relative standard deviations (RSD) of 2.65%, 2.51%, and 3.34% with Cd(II), Pb(II), and In(III), respectively (n = 8). The electrode can be used to test the content of Cd(II), In(III), and Pb(II) in water.

Preparation of Electrode Material Based to Bismuth Oxide-Attached Multiwalled Carbon Nanotubes for Lead (II) Ion Determination

“…This trend, resulting from the change in surface coverage and thickness of the electrode/electrolyte interface (electrical double layer (EDL)), was also observed earlier [39]. The peak ( * ) close to 0 V in the CV curve for the Bi 2 O 3 @CNTs-50 electrode (Figure 4(a)) is similar to that observed in a previous study [40], but it did not appear for Bi 2 O 3 /Pt [37] and Bi 2 O 3 /Au [39] electrodes. Notably, BiO + was formed and captured on the double layer until saturation under controlled charge transfer and mass diffusion [38].…”

“…However, the capacitance (C e ) of Bi 2 O 3 @CNTs is higher than that of the CNTs owing to the high permittivity of Bi 2 O 3 [54]. The multistep mechanism of the electrochemical process on the electrode surface in the presence of Bi [40] affects the charge transfer resistance (R ct ) of the EDL [55] that may have led to a higher R ct of the Bi 2 O 3 @CNTs electrode than that observed for the CNTs electrode. However, the values of (R ct + R e ) for the Bi 2 O 3 @CNTs electrodes are generally lower than that for the CNTs electrode, indicating the positive effect of Bi 2 O 3 on electrical signal conductivity.…”

“…A solution mixture of 0.1 M KCl and 0.1 M acetate buffer (pH 4.0) was used as the electrolytic support for all electrochemical tests. The cyclic voltammetry (CV) measurements with the potential ranging from -0.2 V to 1.0 V at different scan rates (10,20,30,40,50,70,100,150, and 200 mV/s) and electrochemical impedance spectroscopy (EIS) with a 5 mV amplitude over a frequency range of 1-10 5 Hz were conducted on the electrodes in the electrolyte containing 50 mM K 3 Fe(CN) 6 .…”