The Adsorption and Condensed Film Formation of Cetyltrimethylammonium Bromide at the Mercury/Electrolyte Interface

The adsorption of cetyltrimethyammonium bromide (CTAB) on a hanging mercury electrode is studied in various electrolyte systems and temperatures. A condensed film is formed at negative potentials and at room temperature only in the presence of KBr. The decrease of the temperature favors the formatio...

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Bibliographic Details
Published in:Journal of colloid and interface science 2002-04, Vol.248 (2), p.347-354
Main Authors: Avranas, Antonis, Retter, Utz, Malasidou, Efi
Format: Article
Language:English
Subjects:
Adsorption
Cetrimonium Compounds - chemistry
cetyltrimethylammonium bromide
Chemistry
condensed film
differential capacity
Electric Capacitance
Electrochemistry
Electrolytes - chemistry
Exact sciences and technology
General and physical chemistry
hysterisis phenomena
Membranes, Artificial
Mercury - chemistry
Study of interfaces
Surface Properties
Thermodynamics
Time Factors
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Summary:The adsorption of cetyltrimethyammonium bromide (CTAB) on a hanging mercury electrode is studied in various electrolyte systems and temperatures. A condensed film is formed at negative potentials and at room temperature only in the presence of KBr. The decrease of the temperature favors the formation of the condensed film. Hysterisis phenomena are observed during the potential scans at both directions. Capacity time curves at the potentials where the film is formed show a nucleation and growth mechanism, with induction time depending on potential, which has been investigated using Avrami formulation and has been explained as a progressive one-dimensional nucleation with constant growth rate. The nucleation rate increases while moving toward more negative potentials. A linear decrease of the capacitance with time was observed in some cases independent of the measuring potential in a relative large potential range. The different types of micelles can affect the adsorption of CTAB on mercury. An unusual capacitance transient observed at a very narrow negative potential range is attributed to the formation of hemicylinders. The condensed film in the presence of the other electrolytes is observed only at high concentrations (1 M) and very low temperatures (5°C).
ISSN:0021-9797
1095-7103
DOI:10.1006/jcis.2001.8180