Preparation of a Clay-modified Carbon Paste Electrode Based on 2-Thiazoline-2-thiol-hexadecylammonium Sorption for Sensitive Determination of Mercury

A montmorillonite from Wyoming-USA was used to prepare an organo-clay complex, named 2-thiazoline-2-thiol-hexadecyltrimethylammonium-clay (TZT-HDTA-clay), for the purpose of the selective adsorption of the heavy metals ions and possible use as a chemically modified carbon paste electrode (CMCPE). Ad...

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Bibliographic Details
Published in:Analytical Sciences 2005, Vol.21(11), pp.1309-1316
Main Authors: FILHO, Newton L. Dias, CARMO, Devaney R. do, GESSNER, Fergus, ROSA, André H.
Format: Article
Language:English
Subjects:
Adsorption
Aluminum Silicates - chemistry
Anions - chemistry
Bentonite - chemistry
Calibration
Carbon - chemistry
Cations, Divalent - chemistry
Cetrimonium
Cetrimonium Compounds - chemistry
Clay
Electrochemistry
Fresh Water - analysis
Hydrogen-Ion Concentration
Ion-Selective Electrodes
Mercury - analysis
Mercury - chemistry
Oxidation-Reduction
Reproducibility of Results
Seawater - analysis
Thiazoles - chemistry
Thiazolidines
X-Ray Diffraction
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Summary:A montmorillonite from Wyoming-USA was used to prepare an organo-clay complex, named 2-thiazoline-2-thiol-hexadecyltrimethylammonium-clay (TZT-HDTA-clay), for the purpose of the selective adsorption of the heavy metals ions and possible use as a chemically modified carbon paste electrode (CMCPE). Adsorption isotherms of Hg2+, Pb2+, Cd2+, Cu2+, and Zn2+ from aqueous solutions as a function of the pH were studied at 298 K. Conditions for quantitative retention and elution were established for each metal by batch and column methods. The organo-clay complex was very selective to Hg(II) in aqueous solution in which other metals and ions were also present. The accumulation voltammetry of Hg(II) was studied at a carbon paste electrode chemically modified with this material. The mercury response was evaluated with respect to the pH, electrode composition, preconcentration time, mercury concentration, “cleaning” solution, possible interferences and other variables. A carbon paste electrode modified by TZT-HDTA-clay showed two peaks: one cathodic peak at about 0.0 V and an anodic peak at 0.25 V, scanning the potential from -0.2 to 0.8 V (0.05 M KNO3 vs. Ag/AgCl). The anodic peak at 0.25 V presents excellent selectivity for Hg(II) ions in the presence of foreign ions. The detection limit was estimated as 0.1 µg L-1. The precision of determination was satisfactory for the respective concentration level.
ISSN:0910-6340
1348-2246
DOI:10.2116/analsci.21.1309