Volume 67, 1971

Selective adsorption of n-fatty acids at the silica/benzene and silica/n-hexane interface. Part 1.—Adsorption isotherms

Abstract

The selective adsorption isotherms of the n-C6, C8, C12, C14 and C16 fatty acids at the silica/benzene and silica/n-hexane interface have been determined at 27°C. The adsorbents used were a fully hydroxylated silica carrying a small concentration of micropores on its surface (R.A.3) and an annealed but still fully hydroxylated silica (R.R.A.3/700). With the exception of the C6 and C8 acids the adsorption isotherms with the benzene solutions were independent of the chain length of the fatty acid. Adsorption from the n-hexane solutions showed that lengthening the hydrocarbon chain of the adsorbate decreased the surface coverage at fixed equilibrium solution concentration. The adsorption isotherms obtained from benzene solutions showed a limiting surface coverage equivalent to about 0.5 molecule of fatty acid per 100 Å2 of adsorbent surface for the C8-C16 acids. From the n-hexane solutions the limiting adsorption ranged from about 1.85 solute molecules per 100 Å2 of solid surface for the C6 acid down to 1.40 for the C16 species. Partly dehydroxylating the adsorbent so as to yield a silica surface carrying only single hydroxyls (R.A.3/700) resulted in this material showing virtually no selectivity for fatty acid adsorption from benzene solutions.

Article information

Article type
Paper

Trans. Faraday Soc., 1971,67, 493-499

Selective adsorption of n-fatty acids at the silica/benzene and silica/n-hexane interface. Part 1.—Adsorption isotherms

C. G. Armistead, A. J. Tyler and J. A. Hockey, Trans. Faraday Soc., 1971, 67, 493 DOI: 10.1039/TF9716700493

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