[BMIm][PF6]/silicon oil/multi-walled carbon nanotubes paste electrode: Electrochemical properties and application for lead and cadmium ion determinations

Abstract

The electroanalytical methods have been developed for wide application, especially for trace metal ions. In this study, the applicability of 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIm][PF6]) ionic liquid as a pasting binder to fabricate a multi-walled carbon nanotube paste electrode (MWCNT PE) for detecting Pb2+ and Cd2+ ions was evaluated. The electrochemical properties of electrodes were explored by cyclic voltammetry, electrochemical impedance spectroscopy and linear sweep anodic stripping voltammetry. The use of [BMIm][PF6] alone as a conductive binder resulted in an electrode that was unsatisfactory for electrochemical analysis. However, the MWCNT PE with the pasting mixture of silicon oil and [BMIm][PF6] presented excellent sensitivity for the Pb2+ and Cd2+ determinations, with limits of detection of 2.25 and 1.59 mg L?1, respectively. The proposed electrode was demonstrated to be a reliable sensor for accurately quantifying trace amounts of Pb2+ and Cd2+ ions, exhibiting good repeatability, reproducibility and stability.