Double-walled carbon nanotubes functionalized with Allium sativum (garlic extract): Analytical applications for Pb(II) electrochemical sensing

Abstract

In the present work, we report an electrochemical sensor for the selective and sensitive quantification of Pb(II) based the use of glassy carbon electrodes (GCEs) modified with double-walled carbon nanotubes (DWCNTs) non-covalently functionalized with Allium sativum extract (garlic extract, Gar), (GCE/DWCNTs-Gar). FTIR, UV–vis spectroscopy, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry were used to characterize the DWCNTs-Gar dispersion. Pb(II) was accumulated at GCE/DWCNTs-Gar at open circuit potential for 20.0 min via complex formation with the organosulfur compounds residues present in the Gar extract, followed by the reduction at −0.900 V, and final reoxidation by voltammetric stripping. The sensitivity was (72 ± 8) × 10−3 μA μg−1 L, the reproducibility was 11.1% using five different dispersions, and the detection limit was 1.5 μg L−1. The quantification of Pb(II) was highly selective even in the presence of other cations of ecotoxicological relevance such as Cd (II), Hg(II), As(III), Co(II), and Cr(III). The proposed sensor was successfully used for the quantification of Pb(II) in river and lagoon water.