The Transformation of Uranyl Oxide Hydrates: The Effect of Dehydration on Synthetic Metaschoepite and Its Alteration to Becquerelite

Autor:	Sue B. Clark, R. A. Fjeld, A. G. Sowder
Rok vydání:	1999
Předmět:	Thermogravimetric analysis Inorganic chemistry Energy-dispersive X-ray spectroscopy Oxide chemistry.chemical_element General Chemistry Uranium Uranyl chemistry.chemical_compound chemistry Environmental Chemistry Uranium oxide Schoepite Nuclear chemistry Uranium in the environment
Zdroj:	Environmental Science & Technology. 33:3552-3557
ISSN:	1520-5851 0013-936X
DOI:	10.1021/es9901516
Popis:	The U(VI) solid phases schoepite, metaschoepite, and dehydrated schoepite are important reservoirs of mobile uranium in the environment. These simple uranyl oxide hydrates result from weathering of uranium minerals and the corrosion of anthropogenic uranium solids. We have studied the role of hydrational water among these phases and in subsequent tranformation to other secondary metal-U(VI) oxide hydrates. Synthetic metaschoepite (MS, UO3·2.0H2O), its dehydrated phases, and its secondary alteration products were characterized using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), and high-resolution thermogravimetric analysis (HRTGA). Drying MS at 105 °C resulted in the formation of a dehydrated phase (UO3·0.9H2O) that was structurally distinct from natural dehydrated schoepite (DS, UO3·0.75H2O) reported by others. Unlike natural DS, our dehydrated material was easily rehydrated, although crystallinity of the rehydrated phase was reduced. The ...
Databáze:	OpenAIRE
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