Equilibrium Adsorption of Surfactants at the Gas-Liquid Interface

Karakashev, S., Nguyen, A.V. and Miller, J.D. (2008) Equilibrium Adsorption of Surfactants at the Gas-Liquid Interface. Advances in Polymer Science, 218 1: 25-55. doi:10.1007/12_2008_161


Author Karakashev, S.
Nguyen, A.V.
Miller, J.D.
Title Equilibrium Adsorption of Surfactants at the Gas-Liquid Interface
Journal name Advances in Polymer Science   Check publisher's open access policy
ISSN 0065-3195
ISBN 978-3-540-69809-8
Publication date 2008-01-01
Year available 2008
Sub-type Critical review of research, literature review, critical commentary
DOI 10.1007/12_2008_161
Open Access Status
Volume 218
Issue 1
Start page 25
End page 55
Total pages 31
Editor Narayanan, R
Place of publication Germany
Publisher Springer Berlin
Language eng
Subject C1
9602 Atmosphere and Weather
0904 Chemical Engineering
Abstract Theories on equilibrium adsorption of surfactants at the gas-liquid interface have been reviewed and validated. For the adsorption of nonionic surfactants, the thermodynamic approach of Butler has been used, in conjunction with the Lucassen-Reynders dividing surface, to describe the adsorption layer state and adsorption isotherm as a function of partial molar area. Applying the Butler-Lucassen-Reynders modeling approach provides the generalized adsorption isotherm and equation of state, which is capable of describing the effect of the surfactant orientational states and aggregation at the interface. For Langmuirian and Frumkinian surfactant adsorption, the Butler-Lucassen-Reynders modeling approach produces the same predictions for surface tension as described by the well-known Langmuir and Frumkin adsorption isotherms. The adsorption of ionic surfactants and ionic-nonionic surfactant mixtures has been described following the traditional approach with the Gibbs dividing surface and Gibbs adsorption isotherm, and the Gouy-Chapman electrical double layer electrostatics. The developed theories have been validated through comparison with the experimental data on surface tension. Regression analysis by minimizing the reduced chi-square has been used to bestfit the models to the experimental data to obtain the model free parameters. For the surfactant homologous series of octaethyleneglycol-n-alkyl ethers CnH2n+1O(CH2CH2)(8)H, the negative sign of the intermolecular interaction parameter obtained in the regression analysis of surface tension has not been resolved by the model for the surfactant orientational state at the interface. For the surfactant series, the surface aggregation model gives physically consistent fitting and parameters. The models for adsorption of ionic surfactants have been validated using the surface tension of a series of sodium n-hexadecylsulfates with the sulfate group located at the different positions in the hydrocarbon chain, a homologue series of sodium alkyl sulfates, and a series of alkali dodecyl sulfates. Improved adsorption models for ionic surfactants have been developed through fundamental modeling of the adsorption processes and the molecular interactions in the adsorption layers. The improved predictions reduce the required number of free parameters and agree with the surface tension and surface potential data better than the conventional models.
Keyword Polymer Science
Polymer Science
Q-Index Code C1
Q-Index Status Confirmed Code
Grant ID INT 0227583
DE-FG02-93ER14315
Institutional Status UQ

Document type: Journal Article
Sub-type: Critical review of research, literature review, critical commentary
Collection: 2009 Higher Education Research Data Collection
 
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Created: Fri, 17 Apr 2009, 01:18:13 EST by Katherine Montagu on behalf of School of Chemical Engineering