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

Published online by Cambridge University Press:  02 April 2024

J. Cornejo ,
M. C. Hermosin ,
J. L. White ,
J. R. Barnes  and
S. L. Hem
J. Cornejo*
Affiliation:
Department of Agronomy, Purdue University, West Lafayette, Indiana 47907
M. C. Hermosin*
Affiliation:
Department of Agronomy, Purdue University, West Lafayette, Indiana 47907
J. L. White
Affiliation:
Department of Agronomy, Purdue University, West Lafayette, Indiana 47907
J. R. Barnes
Affiliation:
Department of Chemistry, Purdue University, West Lafayette, Indiana 47907
S. L. Hem
Affiliation:
Department of Industrial and Physical Pharmacy, Purdue University, West Lafayette, Indiana 47907
*
4Present address: Centro de Edafologia y Biologia Aplicada del Cuarto, C.S.I.C, Apartado 1052, Sevilla, Spain.
4Present address: Centro de Edafologia y Biologia Aplicada del Cuarto, C.S.I.C, Apartado 1052, Sevilla, Spain.
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Abstract

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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.

Резюме

Резюме

Оценивалась роль адсорбированного и структурного Fe3+ в палыгорските и сепиолите по отношению к окислению гидрокортизона в водных растворах путем электронного спинового резонанса и Уф-видимой спектроскопии. Естественные Fe3+, адсорбированные на поверхности, показали значительную, хотя меньшую, чем октаэдрические Fe3+, активность в процессе окисления. Кинетика окислительной деградации гидрокортизона палыгорскитом, по-видимому, состоит из двух кажущихся первого порядка реакций, которые могут быть связаны с двумя типами мест для Fе в палыгорските. Низшая окислительная сила сепиолита для деградации гидрокортизона обусловлена его низким содержанием Fe3+. [E.C.]

Resümee

Resümee

Der Einfluß von Fe3+, das an Palygorskit und Sepiolith adsorbiert ist oder sich in deren Struktur befindet, wurde im Hinblick auf die Oxidation von Hydrocortison in wässriger Subspension mittels Elektronenspinresonanz und UV-VIS-Spektroskopie untersucht. Natürliches, an der Oberfläche adsorbiertes Fe3+ zeigt einen erheblichen Einfluß auf den Oxidationsprozeß, der jedoch kleiner ist als der von oktaedrischem Fe3+. Die Kinetik der oxidativen Degradation von Hydrocortison durch Palygorskit scheint aus zwei Reaktionen erster Ordnung zu bestehen, die anscheinend mit zwei Arten von Fe-Plätzen im Palygorskit zusammenhängen. Das geringe Oxidationsvermögen von Sepiolith bei der Hydrocortison-Degradation hängt mit dessen sehr geringem Fe3+-Gehalt zusammen. [U.W.]

Résumé

Résumé

Le rôle de Fe3+ adsorbé et structural dans la patygorskite et la sépiolite vis à vis de l'oxidation de l'hydrocortisone en suspension aqueuse a été evalué en utilisant la résonnance à spin d’électrons et la spectroscopie UV-visible. Le Fe3+ naturel adsorbé à la surface a montré une activité importante dans le procédé d'oxidation, quoique plus petite que Fe3+ octaédral. La kinétique de dégradation oxidative de l'hydrocortisone par la palygorskite semble être composée de deux réactions de premier ordre qui pourraient être associées à deux sourtes de sites pour Fe dans la palygorskite. La capacité d'oxidation moindre de la sépiolite pour la dégradation de l'hydrocortisone est due à son très has contenu en Fe3+. [D.J.]

Keywords

CatalysisElectron spin resonanceHydrocortisoneIronOxidationPalygorskiteSepiolite
Type
Research Article
Information
Clays and Clay Minerals , Volume 31 , Issue 2 , April 1983 , pp. 109 - 112
Copyright
Copyright © 1983, The Clay Minerals Society

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