Surfactant Adsorption at the Metal–Oil Interface

The structure of the adsorbed palmitic acid at the iron oxide/oil interface has been investigated using polarized neutron reflectometry. The palmitic acid was found to be strongly adsorbed at the oxide/oil interface resulting in a monolayer of thickness 16 ± 4 Å for 150 and 500 ppm palmitic acid con...

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Bibliographic Details
Published in:Langmuir 2011-05, Vol.27 (10), p.6085-6090
Main Authors: Campana, Mario, Teichert, Anke, Clarke, Stuart, Steitz, Roland, Webster, John. R. P., Zarbakhsh, Ali
Format: Article
Language:English
Subjects:
Chemistry
Exact sciences and technology
General and physical chemistry
Interfaces: Adsorption, Reactions, Films, Forces
Surface physical chemistry
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Summary:The structure of the adsorbed palmitic acid at the iron oxide/oil interface has been investigated using polarized neutron reflectometry. The palmitic acid was found to be strongly adsorbed at the oxide/oil interface resulting in a monolayer of thickness 16 ± 4 Å for 150 and 500 ppm palmitic acid concentrations (16 ± 5 Å for the 1000 ppm solution). These layer thicknesses suggest tilt for the palmitic acid molecules with respect to the interface. The model also requires a second diffuse layer extending in the bulk oil. The thickness of this diffuse layer was 35 ± 17 Å for the 150 ppm solution and 45 ± 22 Å for 500 and 1000 ppm solution. The composition profiles at the interface suggest a depletion of the oil in the vicinity of the interface as the concentration of palmitic acid increases.
ISSN:0743-7463
1520-5827
DOI:10.1021/la200670w