Chemical Speciation of Uranium(VI) in Marine Environments: Complexation of Calcium and Magnesium Ions with [(UO2)(CO3)3]4− and the Effect on the Extraction of Uranium from Seawater. Issue 44 (11th September 2014)

• Record Type: Journal Article
• Authors: Endrizzi, Francesco; Rao, Linfeng
• Is Part Of: Chemistry. Volume 20:Issue 44(2014)
• Page Start: 14499
• Page End: 14506
• Publication Date: 2014-09-11
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201403262
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>The interactions of Ca²⁺ and Mg²⁺ with [UO₂(CO₃)₃]⁴⁻ were studied by calcium ion selective electrode potentiometry and spectrophotometry. The stability constants of ternary Ca‐UO₂‐CO₃ and Mg‐UO₂‐CO₃ complexes were determined with calcium ion selective electrode potentiometry and optical absorption spectrophotometry, respectively. The enthalpies of complexation for two successive complexes, [CaUO₂(CO₃)₃]²⁻ and [Ca₂UO₂(CO₃)₃](aq), were determined for the first time by microcalorimetry. The data help to revise the speciation of uranium(VI) species under seawater conditions. In contrast to the previously accepted assumption that the highly negatively charged [UO₂(CO₃)₃]⁴⁻ is the dominant species, the revised speciation indicates that the dominant aqueous uranium(VI) species under seawater conditions is the neutral [Ca₂UO₂(CO₃)₃](aq). The results have a significant impact on the strategies for developing efficient sorption processes to extract uranium from seawater.</p> </abstract>