Enthalpy of Uranium Adsorption onto Hematite.
Environ Sci Technol
; 54(23): 15004-15012, 2020 12 01.
Article
em En
| MEDLINE
| ID: mdl-33166114
ABSTRACT
The influence of temperature on the adsorption of metal ions at the solid-water interface is often overlooked, despite the important role that adsorption plays in metal-ion fate and transport in the natural environment where temperatures vary widely. Herein, we examine the temperature-dependent adsorption of uranium, a widespread radioactive contaminant, onto the ubiquitous iron oxide, hematite. The multitemperature batch adsorption data and surface complexation models indicate that the adsorption of uranium, as the hexavalent uranyl (UO22+) ion, increases significantly with increasing temperature, with an adsorption enthalpy (ΔHads) of +71 kJ mol-1. We suggest that this endothermic, entropically driven adsorption behavior is linked to reorganization of the uranyl-ion hydration and interfacial water structures upon UVI adsorption at the hematite surface. Overall, this work provides fundamental insight into the thermodynamics driving metal-ion adsorption reactions and provides the specific enthalpy value necessary for improved predictive geochemical modeling of UVI adsorption in the environment.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Urânio
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
Environ Sci Technol
Ano de publicação:
2020
Tipo de documento:
Article
País de afiliação:
Estados Unidos