Comparative adsorption of saturated and unsaturated fatty acids at the iron oxide/oil interface
American Chemical Society
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Wood, M., Casford, M., Steitz, R., Zarbakhsh, A., Welbourn, R., & Clarke, S. (2015). Comparative adsorption of saturated and unsaturated fatty acids at the iron oxide/oil interface. Langmuir, 32 534-540. https://doi.org/10.1021/acs.langmuir.5b04435
A detailed comparison of the adsorption behavior of long straight chain saturated and unsaturated fatty acids at the iron oxide/oil interface has been considered using a combination of surface study techniques. Both depletion isotherms and polarized neutron reflectometry (PNR) show that the extent of adsorption decreases as the number of double bonds in the alkyl chains increases. Sum frequency generation spectroscopic measurements demonstrate that there is also an increase in chain disorder within the adsorbed layer as the unsaturation increases. However, for the unsaturated analogues, a decrease in peak intensity is seen for the double bond peak upon heating, which is thought to arise from isomerization in the surface-bound layer. The PNR study of oleic acid adsorption indicates chemisorbed monolayer adsorption, with a further diffuse reversible adsorbed layer formed at higher concentrations.
Mary Wood is grateful for funding from the Oppenheimer Trust. The PNR data were collected using the V6 instrument at the Helmholtz-Zentrum Berlin (experiment number MAT-04-2131).
External DOI: https://doi.org/10.1021/acs.langmuir.5b04435
This record's URL: https://www.repository.cam.ac.uk/handle/1810/253139