Mercury Ion Sensing Using Mercaptosuccinic Acid-Derived Carbon Quantum Dots

Area of Science:

• Materials Science
• Analytical Chemistry
• Nanotechnology

Background:

• Carbon quantum dots (CQDs) are novel nanomaterials with unique optical and electronic properties.
• Mercaptosuccinic acid (MSA) is a common precursor for synthesizing CQDs.
• Sensing metal ions in aqueous solutions is crucial for environmental monitoring and biological applications.

Purpose of the Study:

• To synthesize and characterize carbon quantum dots from mercaptosuccinic acid (MSA-CQDs).
• To investigate the photoluminescence quenching of MSA-CQDs upon interaction with various metal ions.
• To determine the sensing capabilities and detection limits of MSA-CQDs for specific metal ions.

Main Methods:

• Synthesis of MSA-CQDs followed by purification to obtain blue and green fractions.
• Photoluminescence spectroscopy was used to monitor the sensing of metal ions.
• Stern-Volmer analysis was employed to quantify the photoluminescence quenching.
• Detection limits for metal ions were calculated.

Main Results:

• Two distinct fractions of MSA-CQDs (blue and green) were obtained.
• Photoluminescence quenching was observed in the presence of Hg ²⁺ , Fe ³⁺ , Cr ³⁺ , Co ²⁺ , Ag ⁺ , Fe ²⁺ , Cu ²⁺ , and Ni ²⁺ .
• The green MSA-CQDs exhibited the lowest detection limit for Hg ²⁺ at 1.4 ppm.
• Electron transfer mechanisms involving d orbitals of metal ions were proposed.

Conclusions:

• MSA-CQDs are effective fluorescent sensors for detecting multiple metal ions in aqueous solutions.
• The sensitivity of the sensor is metal-ion dependent, with high sensitivity for Hg ²⁺ .
• The developed sensing platform offers a promising approach for trace metal ion detection.