Amino Acid Based MOF: A Promising Green Material for Electrochemical Sensing of Heavy Metal Ions (HMIs)

Abstract

Heavy metal ion (HMI) contamination in freshwater resources has become a serious environmental and public health concern worldwide. Toxic metals such as lead (Pb) and mercury (Hg) can accumulate in living organisms and pose significant health risks due to their persistence and non-biodegradable nature. Therefore, the development of efficient and sensitive methods for the detection of HMIs in water is essential before its utilization for domestic, agricultural, and industrial purposes.

This study presents the synthesis of an amino acid-based Metal–Organic Framework (MOF) as a green and effective material for electrochemical sensing of heavy metal ions. An energy-efficient microwave-assisted synthesis method was employed to prepare a MOF using bismuth and cobalt as central metal ions and L-tyrosine as the organic linker. L-tyrosine, a naturally occurring and biocompatible amino acid, was selected to enhance the environmental sustainability of the synthesized material. Microwave synthesis offers several advantages, including reduced reaction time, lower energy consumption, high product yield, and minimal environmental impact.

The synthesized MOF exhibited excellent surface characteristics suitable for sensing applications. The incorporation of the ionic liquid BMIM BF₄ significantly improved the electrical conductivity, increased the availability of adsorption sites for heavy metal ions, and enhanced the sensing performance of the material. The developed electrochemical sensing platform demonstrated a large active surface area, efficient charge transfer capability, enhanced conductivity, and good operational stability.

The structural and physicochemical properties of the synthesized composite were characterized using Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction (XRD) techniques. Furthermore, the electrochemical performance of the MOF-based electrode (L-Tyr-BiCo/IL/GCE) was evaluated through cyclic voltammetry and electrochemical impedance spectroscopy. The results indicate that the developed amino acid-based MOF is a promising green material for the sensitive and reliable detection of heavy metal ions in aqueous environments