Role of Ferric Iron in the Oxidation of Hydrocortisone by Sepiolite and Palygorskite

J. Cornejo1, 4, M. C. Hermosin1, 4, J. L. White1, J. R. Barnes2 and S. L. Hem3
1 Department of Agronomy, Purdue University, West Lafayette, Indiana 47907
2 Department of Chemistry, Purdue University, West Lafayette, Indiana 47907
3 Department of Industrial and Physical Pharmacy, Purdue University, West Lafayette, Indiana 47907
4 Present address: Centro de Edafologia y Biologia Aplicada del Cuarto, C.S.I.C., Apartado 1052, Sevilla, Spain.

Abstract: The role of adsorbed and structural Fe3+ in palygorskite and sepiolite with respect to the oxidation of hydrocortisone in aqueous suspension has been evaluated using electron spin resonance and UV-visible spectroscopy. Natural surface-adsorbed Fe3+ showed an important activity in the oxidation process, although smaller than octahedral Fe3+. The kinetics of oxidative degradation of hydrocortisone by palygorskite appear to be composed of two apparent first order reactions which may be associated with two kinds of sites for Fe in palygorskite. The lower oxidizing power of sepiolite for hydrocortisone degradation is due to its very low Fe3+ content.

Key Words: Catalysis • Electron spin resonance • Hydrocortisone • Iron • Oxidation • Palygorskite • Sepiolite

Clays and Clay Minerals; April 1983 v. 31; no. 2; p. 109-112; DOI: 10.1346/CCMN.1983.0310204
© 1983, The Clay Minerals Society
Clay Minerals Society (www.clays.org)