Electrochemical Sensors for Heavy Metal Ion Detection in Aqueous Medium: A Systematic Review

Abstract

Heavy metal ions (HMIs) are very harmful to the ecosystem when they are present in excess of the recommended limits. They are carcinogenic in nature and can cause serious health issues. So, it is important to detect the metal ions quickly and accurately. The metal ions arsenic (As³⁺), cadmium (Cd²⁺), chromium (Cr³⁺), lead (Pb²⁺), and mercury (Hg²⁺) are considered to be very toxic among other metal ions. Standard analytical methods like atomic absorption spectroscopy, atomic fluorescence spectroscopy, and X-ray fluorescence spectroscopy are used to detect HMIs. But these methods necessitate highly technical equipment and lengthy procedures with skilled personnel. So, electrochemical sensing methods are considered to be more advantageous because of their quick analysis with precision and simplicity to operate. They can detect a wide range of heavy metals providing real-time monitoring and are cost-effective and enable multiparametric detection. Various sensing applications necessitate severe regulation regarding the modification of electrode surfaces. Numerous nanomaterials such as graphene, carbon nanotubes, and metal nanoparticles have been extensively explored as interface materials in electrode modifiers. These nanoparticles offer excellent electrical conductivity, distinctive catalytic properties, and high surface area resulting in enhanced electrochemical performance. This review examines different HMI detection methods in an aqueous medium by an electrochemical sensing approach and studies the recent developments in interface materials for altering the electrodes.

Figure 1

Number of publications in the field of electrochemical detection of heavy metal ions in the last 10 years (www.scopus.com; keywords: electrochemical detection of heavy metal ion).

Figure 2

Block diagram of an atomic absorption spectrometer.

Figure 3

Block diagram of an atomic fluorescence spectrometer.

Figure 4

X-ray fluorescence spectroscopy.

Figure 5

Experimental setup of potentiostatic techniques.

Figure 6

Experimental setup of galvanostatic techniques.

Figure 7

Diagrammatic representation of electrochemical impedance spectroscopy.

Figure 8

Schematic diagram of electrochemical sensor. Reprinted with permission from ref (51). Copyright 2021 Elsevier.

Figure 9

(a) Typical SWASV response of arsenic(III) at a Au/Fe₃O₄ screen-printed electrode across different concentrations. (b) Corresponding linear calibration plot of peak current against arsenic concentrations from 0.1 to 10 ppb Insets in (a) and (b) are the enlarged views that correspond to a range of 0.1–2 ppb. Reprinted with permission from ref (70). Copyright 2018 American Chemical Society.

Figure 10

SWASV response and corresponding calibration plot (inset) of magnesium–aluminum double layered hydroxide/Nafion glass carbon electrode toward cadmium over the concentration range of (a) 0.1–1.9 μM by depositing for 120 s and (b) 20–60 nm by depositing for 30 min. Reprinted with permission from ref (96). Copyright 2018 Royal Society of Chemistry.

Figure 11

(a) DPV curves of cadmium with various concentration levels (from 1 nM to 10 μM) on a PB-PEDOT/LSG/glassy carbon electrode. (b) Magnified DPV curves of cadmium with low concentration (from 1 to 10 nM). (c,d) corresponding current versus cadmium concentration calibration curves. Reproduced from open access article ref (97) distributed under the terms and conditions of the Creative Commons Attribution license http://creativecommons.org/licenses/by/4.0/.

Figure 12

DPV of graphite paste electrode/silver nanoparticles biphenol biphenoquinone nanoribbons in 0.1 M PBS containing various concentrations of chromium. Insets represent the plots of anodic peak current Vs concentrations of chromium. The error bars represents the standard deviation of three parallel test Reprinted with permission from ref (131). Copyright 2018 Elsevier.

Figure 13

SWASV for different concentrations of lead ions from acarbon paste electrode modified with polydiaminonaphthalene and bismuth film. (inset) Calibration curve of lead ions. Reproduced from open access article ref (162) distributed under the terms and conditions of the Creative Commons Attribution license http://creativecommons.org/licenses/by/4.0/..

Figure 14

(a) DPV curve of zinc oxide/reduced graphene oxide/polypyrrole for different mercury ion concentrations. (b) Corresponding calibration curve of mercury ion concentrations. Reprinted with permission from ref (182). Copyright 2018 Elsevier.