Adsorption of oleic acid at sillimanite/water interface

Vijaya Kumar, T V and Prabhakar, S and Bhaskar Raju, G (2002) Adsorption of oleic acid at sillimanite/water interface. Journal of Colloid and Interface Science, 247 (2). pp. 275-281.

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Abstract

The interaction of oleic acid at sillimanite-water interface was studied by adsorption, FT-IR, and zeta potential measurements. The isoelectric point (IEP) of sillimanite obtained at pH 8.0 was found to shift in the presence of oleic acid. This shift in IEP was attributed to chemisorption of oleic acid on sillimanite. Adsorption experiments were conducted at pH 8.0, where the sillimanite surface is neutral. The adsorption isotherm exhibited a plateau around 5 mumol/m(2) that correspond to a monolayer formation. Adsorption of oleic acid on sillimanite, alumina, and aluminum hydroxide was studied by FT-IR. Chemisorption of oleic acid on the above substrates was confirmed by FT-IR studies. Hydroxylation of mineral surface was found to be essential for the adsorption of oleic acid molecules. These surface hydroxyl sites were observed to facilitate deprotonation of oleic acid and its subsequent adsorption. Thus protons from oleic acid react with surface hydroxyl groups and form water molecules. Based on the experimental results, the mechanism of oleic acid adsorption on mineral substrate was proposed. Free energy of adsorption was estimated using the Stern-Graham equation for a sillimanite-oleate system.

Item Type:Article
Official URL/DOI:DOI: 10.1006/jcis.2001.8131
Uncontrolled Keywords:sillimanite; electrokinetic measurements; adsorption; FT-IR studies; free energy of adsorption
Divisions:NML Chennai
ID Code:3578
Deposited By:Mr. G Shailendra Kumar
Deposited On:25 Jul 2011 18:15
Last Modified:28 Jan 2015 10:32
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