Titre du document / Document title

Thermal decomposition of sabugalite : A controlled rate thermal analysis study

Auteur(s) / Author(s)

FROST R. L. ⁽¹⁾ ; KRISTOF J. ⁽²⁾ ; MARTENS W. N. ⁽²⁾ ; WEIER M. L. ⁽¹⁾ ; HORVATH Erzsébet ⁽³⁾ ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

⁽¹⁾ Inorganic Materials Research Program, School of Physical and Chemical Sciences, Queensland University of Technology GPO Box 2434, Brisbane Queensland 4001, AUSTRALIE
⁽²⁾ Department of Analytical Chemistry, University of Veszprém, P.O. Box 158, 8201 Veszprém, HONGRIE
⁽³⁾ Department of Environmental Engineering and Chemical Technology, University of Veszprém, P.O. Box 158, 8201 Veszprém, HONGRIE

Résumé / Abstract

The mineral sabugalite (HAl)_0.5[(UO₂)₂(PO₄)]₂·8H₂O, has been studied using a combination of energy dispersive X-ray analysis, X-ray diffraction, dynamic and controlled rate thermal analysis techniques. X-ray diffraction shows that the starting material in the thermal decomposition is sabugalite and the product of the thermal treatment is a mixture of aluminium and uranyl phosphates. Four mass loss steps are observed for the dehydration of sabugalite at 48°C (temperature range 39 to 59°C), 84°C (temperature range 59 to 109°C), 127°C (temperature range 109 to 165°C) and around 270°C (temperature range 175 to 525°C) with mass losses of 2.8, 6.5, 2.3 and 4.4%, respectively, making a total mass loss of water of 16.0%. In the CRTA experiment mass loss stages were found at 60, 97, 140 and 270°C which correspond to four dehydration steps involving the loss of 2, 6, 6 and 2 moles of water. These mass losses result in the formation of four phases namely meta(I)sabugalite, meta(II)sabugalite, meta(III)sabugalite and finally uranyl phosphate and alumina phosphates. The use of a combination of dynamic and controlled rate thermal analysis techniques enabled a definitive study of the thermal decomposition of sabugalite. While the temperature ranges and the mass losses vary due to the different experimental conditions, the results of the CRTA analysis should be considered as standard data due to the quasi-equilibrium nature of the thermal decomposition process.

Revue / Journal Title

Journal of thermal analysis and calorimetry   ISSN 1388-6150 

Source / Source

2006, vol. 83, n^o3, pp. 675-679 [5 page(s) (article)] (25 ref.)

Langue / Language

Anglais

Editeur / Publisher

Springer, Dordrecht, PAYS-BAS  (1998) (Revue)

Mots-clés anglais / English Keywords

Controlled rate thermal analysis ; Morphology ; Surface structure ; Phosphorus compound ; Inorganic anion ; Scanning electron microscopy ; X ray diffraction ; Phosphates ; Sabugalite ; Dehydroxylation ; Dehydration ; Pyrolysis ;

Mots-clés français / French Keywords

Analyse thermique vitesse contrôlée ; Morphologie ; Structure surface ; Phosphore composé ; Anion minéral ; Microscopie électronique balayage ; Diffraction RX ; Phosphate ; Sabugalite ; Déshydroxylation ; Déshydratation ; Pyrolyse ;

Mots-clés espagnols / Spanish Keywords

Morfología ; Estructura superficie ; Fósforo compuesto ; Anión inorgánico ; Microscopía electrónica barrido ; Difracción RX ; Fosfato ; Deshidroxilación ; Deshidratación ; Pirólisis ;

Mots-clés d'auteur / Author Keywords

controlled rate thermal analysis (CRTA) ; dehydration ; dehydroxylation ; metasabugalite ; sabugalite ;

Localisation / Location

INIST-CNRS, Cote INIST : 6367, 35400013247870.0250