Cd2+ Detection by an Electrochemical Electrode Based on MWCNT-Orange Peel Activated Carbon

This study reports the development of a new electrochemical sensor based on a carbon paste electrode (CPE) composed of biomass-based orange peel activated carbon (ACOP) and multiwalled carbon nanotubes (MWCNTs), and this composite is used for the electrochemical detection of cadmium ions (Cd2+). The ACOP/MWCNT composite was characterized by FTIR, Raman, and electrochemical impedance spectroscopy. The electrochemical evaluation of Cd2+ was performed using square wave and cyclic voltammetry. The ACOP/MWCNT-CPE electrochemical sensor exhibited a coefficient of determination r(2 )of 0.9907, a limit of detection of 0.91 +/- 0.79 mu mol L-1, and a limit of quantification of 3.00 +/- 2.60 mu mol L-1. In addition, the developed sensor can selectively detect Cd2+ in the presence of different interferents such as Zn2+, Pb2+, Ni2+, Co2+, Cu2+, and Fe2+ with a relative standard deviation (RSD) close to 100%, carried out in triplicate experiments. The ACOP/MWCNT-CPE presented high sensitivity, stability, and reproducibility and was successfully applied for the detection of Cd2+ in river water samples with recovery rate values ranging from 97.33 to 115.6%, demonstrating to be a very promising analytical alternative for the determination of cadmium ions in this matrix.

Automated summary

This study presents the development of a novel electrochemical sensor based on a carbon paste electrode composed of biomass-based orange peel activated carbon and multiwalled carbon nanotubes. The sensor showed high sensitivity, stability, and reproducibility in detecting cadmium ions, and demonstrated selective detection in the presence of various interferents. It has potential application in the determination of cadmium ions in river water samples.