Electrochemical sensors for the detection and quantification of toxic metal ions

Thesis

This thesis presents experimental work with the primary aim of developing sensors for the detection and quantification of the toxic metal ions Hg²⁺, Al³⁺, Zn²⁺, and Li⁺ through electrochemical methods. Chapter 1 describes the fundamentals of electrochemistry, including voltammetric and nano-impact methods. Chapter 2 provides information about chemical reagents, instrumentation and experimental procedures used in this thesis. Chapter 3 outlines the development of a sensor for inorganic Hg²⁺ in aqueous solution using silver nanoparticles with galvanic displacement under a suitable applied potential.

Chapter 4 and Chapter 5 demonstrate the utilization of tannic acid (TA) as a capping agent of gold nanoparticles for the sensitive detection of Al³⁺ and Hg²⁺ toward complexation, respectively. Chapter 6 generalizes and extends these chapters, defining the role of the TA capping agent in the redox activity for Hg²⁺ and Zn²⁺ detection by using the nano-impact method. Chapter 7 outlines the electrochemical dissolution of the citrate-capped gold nanoparticle in cyanide-containing solution, where an understanding of the dissolution mechanism is of great importance for the optimization of gold nanoparticle recovery or refinery via oxidative cyanidation. Finally, Chapter 8 outlines the development of an electrochemical sensor for Li⁺ in authentic human saliva at lithium manganese oxide (LiMn₂O₄)-modified electrodes. The sensing strategy is based on an initial galvanostatic delithiation of LiMn₂O₄ followed by linear stripping voltammetry to detect Li⁺ in the sample.

Overall, the sensing methodology reported in this thesis makes a significant contribution to the application of voltammetric methods for the detection and quantification of toxic metal ions. All sensors reported in this thesis are specifically suitable for routine environmental monitoring, for drinking water and food products quality assessment, or for clinical monitoring and diagnosis applications.

Authors: Suherman, A

• DOI: 10.5287/ora-kea6xd9v2
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford