| Autor: | Robert A. Fjeld, Sue B. Clark, A. G. Sowder |
|---|---|
| Rok vydání: | 2001 |
| Předmět: |
Toxicity characteristic leaching procedure
Sodium bicarbonate Health Toxicology and Mutagenesis Bicarbonate Inorganic chemistry Public Health Environmental and Occupational Health Mineralogy chemistry.chemical_element Uranium Uranyl Pollution Analytical Chemistry Acetic acid chemistry.chemical_compound Nuclear Energy and Engineering chemistry Radiology Nuclear Medicine and imaging Dissolution Schoepite Spectroscopy |
| Zdroj: | Journal of Radioanalytical and Nuclear Chemistry. 248:517-524 |
| ISSN: | 0236-5731 |
| DOI: | 10.1023/a:1010602225070 |
| Popis: | Kinetic dissolution studies were conducted on four prominent U-Ca-PO4 minerals (metaschoepite, becquerelite, chernikovite and metaautunite). Synthetic samples were contacted with four extractants (acetic acid, deionized water, EDTA and sodium bicarbonate) at room temperature at two concentrations, 100 mM and 1 mM. Dissolution progress was monitored by periodic sampling for dissolved U, and dissolution rates were obtained from fits to a three term exponential model. Significant variations were observed in the rate and extent of dissolution among the mineralsexamined. The uranyl phosphates chernikovite and metaautunite proved resistant to dissolution in non-carbonate systems, with dissolution half-times of days to weeks in 100 mM systems and weeks to years in 1 mM systems. In contrast, the uranyl oxide hydrates schoepite and becquerelite were solubilized over much shorter time scales. While 100 mM bicarbonate was successful in dissolving U in all forms, dissolution rates varied among the four minerals. Overall, EDTA was the least sensitive to a 100 to 1 mM drop in its concentration in its solubilization of all four mineral phases, underscoring the importance of organic complexation for the environmental mobility of uranium. |
| Databáze: | OpenAIRE |
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