Adsorbed Cr(III) on Chlorite, Illite, and Kaolinite: An X-ray Photoelectron Spectroscopic Study

M. H. Koppelman1, A. B. Emerson1 and J. G. Dillard
Department of Chemistry, Virginia Polytechnic Institute and State University Blacksburg, Virginia 24061
1 Present address: Georgia Kaolin Research Laboratories, 25 Route 22, East, Springfield, New Jersey 07081.

Abstract: The adsorption of Cr(III) was studied at pH 1, 2, 3, 4, 6, 8, and 10 on chlorite and kaolinite and at pH 1, 2, 3, and 6 on illite. The amount of chromium adsorbed on chlorite varied from 3.1 × 10−5 mole/g at pH 1 to 16.6 × 10−5 mole/g at pH 4, and on illite from 4.9 × 10−5 mole/g to 9.2 × 10−5 mole/g at pH 1 and 3, respectively. Kaolinite adsorbed 3.7 × 10−5 mole Cr/g at pH 1, 2, and 3 and 5.5 × 10−5 mole Cr/g at pH 4. Measurements of the Cr 2p core-level binding energies indicate that chromium is probably adsorbed as a Cr(III) aqua ion at pH values below 4. The binding energies for the Cr 2p level for samples prepared above pH 4 compare favorably with the value determined for chromium hydroxide and lead to the conclusion that the chromium species present at pH 6, 8, and 10 is chromium hydroxide.

Key Words: Adsorption • Binding energy • Chlorite • Chromium • Illite • Kaolinite • XPS

Clays and Clay Minerals; April 1980 v. 28; no. 2; p. 119-124; DOI: 10.1346/CCMN.1980.0280207
© 1980, The Clay Minerals Society
Clay Minerals Society (www.clays.org)