A multi-technique surface study of the mercury(II) chalcogenide ion-selective electrode in saline media

Roland De Marco; B Pejcic; K Prince; A Van Riessen

doi:10.1039/b212914k

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A multi-technique surface study of the mercury(II) chalcogenide ion-selective electrode in saline media

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A multi-technique surface study of the mercury(II) chalcogenide ion-selective electrode in saline media

Roland De Marco, B Pejcic, K Prince and A Van Riessen

The Analyst, Vol.128(6), pp.742-749

2003

DOI: https://doi.org/10.1039/b212914k

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Abstract

chalcogen

chalcogenide

halide

ion

ligand

mercury

organic compound

sea water

silver chloride

silver halide

sodium chloride

unclassified drug

X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), rotating disc electrode-electrochemical impedance spectroscopy (RDE-EIS) and synchrotron radiation-grazing incidence X-ray diffraction (SR-GIXRD) have been used to study the response mechanism of the mercury(II) chalcogenide ion-selective electrode (ISE) in saline media. XPS and SIMS have shown that the chalcogenide surface is poisoned by silver chloride, or a mixture of silver halides, on continuous exposure to synthetic and real seawater. Significantly, the in-situ SR-GIXRD study demonstrated that electrode fouling in synthetic seawater is linked to the formation of poorly crystalline or amorphous silver chloride, and that the low level of free mercury(II) in a calibration buffer (i.e., 10-14 M) is able to undergo metathesis with silver(I) sulfide in the membrane generating mercury(II) sulfide. Significantly, the results of this detailed surface study have shown that silver Chloride fouling of the electrode is ameliorated in real seawater comprising natural organic ligands, and this has been attributed to the peptization of silver chloride by the surfactant-like nature of seawater ligands at pH 8. RDE-EIS aging studies have revealed that the chalcogenide membrane experiences a sluggish charge transfer reaction in seawater, and contrary to a previous report for a static electrode, the seawater matrix does not passivate the RDE. The results of this XPS, SIMS, RDE-EIS and SR-GIXRD study have elucidated the response mechanism of the mercury(II) ISE in saline media.

Details

Title: A multi-technique surface study of the mercury(II) chalcogenide ion-selective electrode in saline media
Authors: Roland De Marco (Author) - Curtin University
B Pejcic (Author) - Curtin University
K Prince (Author) - Australian Nuclear Science and Technology Organization
A Van Riessen (Author) - Curtin University of Technology
Publication details: The Analyst, Vol.128(6), pp.742-749
Publisher: Royal Society of Chemistry (R S C) Publications
Date published: 2003
DOI: 10.1039/b212914k
ISSN: 0003-2654
Organisation Unit: University of the Sunshine Coast, Queensland; Office of the Deputy Vice-Chancellor (Research and Innovation)
Language: English
Record Identifier: 99448794502621
Output Type: Journal article

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