A highly selective mercury electrode based on a diamine donor ligand

Area of Science:

• Analytical Chemistry
• Electrochemistry
• Materials Science

Background:

• Mercury (Hg2+) is a toxic heavy metal pollutant with significant environmental and health impacts.
• Accurate and selective detection of Hg2+ is crucial for environmental monitoring and safety.
• Development of novel electrochemical sensors offers a promising approach for sensitive Hg2+ determination.

Purpose of the Study:

• To synthesize and characterize a novel mercury(II) chloride complex, (H2NCHMeCH2NH2)(H2O)2HgCl2.
• To fabricate a PVC-membrane based potentiometric sensor utilizing this complex for Hg2+ ion detection.
• To evaluate the sensor's performance, including response range, detection limit, selectivity, and stability.

Main Methods:

• Synthesis and characterization of the mercury(II) complex.
• Fabrication of a potentiometric sensor using the complex as the electroactive material in a PVC matrix.
• Electrochemical measurements to determine response linearity, detection limit, and selectivity against interfering ions.
• Stability and response time tests of the fabricated sensor.

Main Results:

• The synthesized complex, (H2NCHMeCH2NH2)(H2O)2HgCl2, was successfully used to create a potentiometric sensor.
• The sensor exhibited a linear response to Hg2+ ions over a concentration range of 1.25x10^-5 to 1.0x10^-1 M.
• A low detection limit of 8.9x10^-6 M, a slope of 25±0.1 mV, and a working pH range of 6.6-9.3 were achieved.
• The sensor demonstrated high selectivity for Hg2+ over various mono-, bi-, and trivalent cations, including common interferents like Ag+ and Cd2+.
• The electrode showed good performance in the presence of methanol and acetone, with a fast response time (10s) and long-term stability (4 months).
• Successful determination of mercury in binary mixtures with 100% recovery was achieved.

Conclusions:

• The developed potentiometric sensor based on the novel mercury(II) complex is highly effective for selective and sensitive detection of Hg2+ ions.
• The sensor's robustness in the presence of organic solvents and its stability make it suitable for practical applications.
• The proposed sensor shows significant potential for real-world environmental monitoring and analysis of mercury contamination.