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Cesium Extraction from Cs0.8Ba0.4Ti8O16 Hollandite Nuclear Waste Form Ceramics in Nitric Acid Solutions

Published online by Cambridge University Press:  01 June 2005

Vittorio Luca ,
David Cassidy ,
Elizabeth Drabarek ,
Keith Murray  and
Boujemaa Moubaraki
Vittorio Luca*
Affiliation:
Australian Nuclear Science and Technology Organization, NSW 2234, Australia
David Cassidy
Affiliation:
Australian Nuclear Science and Technology Organization, NSW 2234, Australia
Elizabeth Drabarek
Affiliation:
Australian Nuclear Science and Technology Organization, NSW 2234, Australia
Keith Murray
Affiliation:
School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
Boujemaa Moubaraki
Affiliation:
School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
*
a) Address all correspondence to this author. e-mail: [email protected]
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Abstract

The leaching of Cs from well-characterized Cs-bearing hollandite powders with ideal formula Cs0.8Ba0.4Ti8O16 was studied at 200 °C under static oxidizing conditions achieved using dilute nitric acid solutions. A variety of techniques were used to elucidate the leaching mechanism including x-ray powder diffraction, magnetic susceptibility, x-ray absorption near edge structure, and electron microscopy. Under the conditions of the study, Cs is leached from Cs-hollandite according to a deceleratory rate law with contracting geometries. The principal reaction products are rutile and brookite. The leaching mechanism involves the formation of a quasi-continuous, and hence relatively impermeable, secondary titanium oxide phase (rutile and/or brookite) on the surfaces of the hollandite crystallites. The driving force for the leaching reaction appears to be the oxidation of Ti3+ in the structure by the oxidizing acid, which then promotes extraction of Cs and Ba from the hollandite tunnels followed by tunnel destabilization and transformation to rutile and brookite.

Keywords

CeramicCorrosionIntercalation
Type
Articles
Information
Journal of Materials Research , Volume 20 , Issue 6 , June 2005 , pp. 1436 - 1446
Copyright
Copyright © Materials Research Society 2005

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