The influence of chain length and electrolyte on the adsorption kinetics of cationic surfactants at the silica-aqueous solution interface

Atkin, R., Craig, V. S. J., Wanless, E. J. and Biggs, S. (2003) The influence of chain length and electrolyte on the adsorption kinetics of cationic surfactants at the silica-aqueous solution interface. Journal of Colloid and Interface Science, 266 2: 236-244. doi:10.1016/S0021-9797(03)00631-3


Author Atkin, R.
Craig, V. S. J.
Wanless, E. J.
Biggs, S.
Title The influence of chain length and electrolyte on the adsorption kinetics of cationic surfactants at the silica-aqueous solution interface
Journal name Journal of Colloid and Interface Science   Check publisher's open access policy
ISSN 0021-9797
1095-7103
Publication date 2003-10-15
Sub-type Article (original research)
DOI 10.1016/S0021-9797(03)00631-3
Open Access Status Not yet assessed
Volume 266
Issue 2
Start page 236
End page 244
Total pages 9
Place of publication Maryland Heights, MO, United States
Publisher Academic Press
Language eng
Abstract The equilibrium and kinetic aspects of the adsorption of alkyltrimethylammonium surfactants at the silica-aqueous solution interface have been investigated using optical reflectometry. The effect of added electrolyte, the length of the hydrocarbon chain, and of the counter- and co-ions has been elucidated. Increasing the length of the surfactant hydrocarbon chain results in the adsorption isotherm being displaced to lower concentrations. The adsorption kinetics indicate that above the cmc micelles are adsorbing directly to the surface and that as the chain length increases the hydrophobicity of the surfactant has a greater influence on the adsoption kinetics. While the addition of 10 mM KBr increases the CTAB maximal surface excess, there is no corresponding increase for the addition of 10 mM KCl to the CTAC system. This is attributed to the decreased binding efficiency of the chloride ion relative to the bromide ion. Variations in the co-ion species (Li, Na, K) have little effect on the adsorption rate and surface excess of CTAC up to a bulk electrolyte concentration of 10 mM. However, the rate of adsorption is increased in the presence of electrolyte. Slow secondary adsorption is seen over a range of concentrations for CTAC in the absence of electrolyte and importantly in the presence of LiCl; the origin of this slow adsorption is attributed to a structural barrier to adsorption.
Keyword Adsorption
Kinetics
Optical reflectometry
Silica
Surfactant
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: Faculty of Engineering, Architecture and Information Technology Publications
 
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