# Mercury Ion Sensing Using Mercaptosuccinic Acid-Derived Carbon Quantum Dots

## TL;DR

Researchers developed carbon quantum dots from mercaptosuccinic acid to detect mercury ions in water with high sensitivity.

## Contribution

The study introduces a novel method for mercury ion sensing using MSA-derived carbon quantum dots with low detection limits.

## Key findings

- Carbon quantum dots showed photoluminescence quenching when exposed to various metal ions, including Hg2+.
- The lowest detection limit for Hg2+ was 1.4 ppm using green MSA-derived carbon quantum dots.
- Spectral properties of the nanoparticles were moderately affected by changes in excitation wavelength and pH.

## Abstract

Carbon quantum dots, prepared from mercaptosuccinic acid
(MSA),
were used to sense metal ions in aqueous solutions. Two fractions
of nanoparticles were obtained after several purification steps, designated
blue and green based on their color under UV illumination. We monitored
the photoluminescence of the carbon nanoparticles upon the addition
of metal ions. Stern–Volmer plots were made to determine whether
photoluminescence quenching of the nanoparticles in solution occurred.
Photoluminescence quenching was observed with adding Hg2+, Fe3+, Cr3+, Co2+, Ag+, Fe2+, Cu2+, and Ni2+. Most of
these metal ions have partially filled d orbitals, contributing to
the transfer of electrons from the photoexcited nanoparticles to the
available empty orbitals of the metal ions. The detection limits for
sensing the metal ions were calculated. The lowest detection limits
observed were for Hg2+, with values of 4.1 and 1.4 ppm
using the blue and green MSA-CQDs, respectively. Changes in the excitation
wavelength and pH had a moderate impact on the spectral properties
of the nanoparticles.