Adsorption of sodium hexanoate on α-alumina

JOURNAL OF COLLOID AND INTERFACE SCIENCE

卷:407

Article

Lee, Seung Yeon^1,2  Welbourn, Rebecca^1,2  Clarke, Stuart M.^1,2  Skoda, Maximilian W. A.³  Clifton, Luke³  Zarbakhsh, Ali⁴ 

[1] Univ Cambridge, BP Inst, Cambridge, England

[2] Univ Cambridge, Dept Chem, Cambridge CB2 1EW, England

[3] Rutherford Appleton Lab, ISIS, Didcot OX11 0QX, Oxon, England

[4] Univ London, Sch Biol & Chem Sci, London, England

关键词: Adsorption;    Sodium hexanoate;    Aluminium oxide;    Ligand exchange;    Neutron reflection;   

DOI  :  10.1016/j.jcis.2013.06.019

来源: Elsevier

【 摘 要 】

Neutron reflection and adsorption isotherm measurements have been used to study the adsorption behaviour of hexanoic acid onto alpha-alumina surfaces. Importantly, the pH dependence of the behaviour has been characterised with a pronounced maximum in adsorption identified at a pH of approximately 5, close to the pK(a) of the acid. The adsorbed layer is identified as a bilayer, which is reasonable given the hydrophilic nature of both side of the layer, and has a thickness of 13 angstrom, suggesting significant extent of interdigitation. At pH 5, the layer has much lower extent of hydration relative to the higher pH of 7, consistent with the increased total adsorption at pH 5. A number of different mechanisms for the binding of the hexanoic acid to the surface are considered. The experimental data, combined with calculations using equilibrium/binding constants of the surface and ligands, indicates that a ligand exchange reaction may be the most significant mechanism. (C) 2013 Elsevier Inc. All rights reserved.

【 授权许可】

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