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Title: Molecular dynamics simulations of uranyl adsorption and structure on the basal surface of muscovite

Anthropogenic activities have led to an increased concentration of uranium on the Earth’s surface and potentially in the subsurface with the development of nuclear waste repositories. Uranium is soluble in groundwater, and its mobility is strongly affected by the presence of clay minerals in soils and in subsurface sediments. We use molecular dynamics simulations to probe the adsorption of aqueous uranyl (UO22+) ions onto the basal surface of muscovite, a suitable proxy for typically ultrafine-grained clay phases. Model systems include the competitive adsorption between potassium counterions and aqueous ions (0.1 M and 1.0 M UO2Cl2 , 0.1 M NaCl). We find that for systems with potassium and uranyl ions present, potassium ions dominate the adsorption phenomenon. Potassium ions adsorb entirely as inner-sphere complexes associated with the ditrigonal cavity of the basal surface. Uranyl ions adsorb in two configurations when it is the only ion species present, and in a single configuration in the presence of potassium. Finally, the majority of adsorbed uranyl ions are tilted less than 45° relative to the muscovite surface, and are associated with the Si4Al2 rings near aluminum substitution sites.
Authors:
 [1] ;  [1] ;  [1]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Geochemistry Department
Publication Date:
OSTI Identifier:
1082222
Report Number(s):
SAND2013--4522J
Journal ID: ISSN 0892-7022; 456021
Grant/Contract Number:
AC04-94AL85000
Type:
Accepted Manuscript
Journal Name:
Molecular Simulation
Additional Journal Information:
Journal Volume: 40; Journal Issue: 7-9; Related Information: Proposed for publication in Molecular Simulation.; Journal ID: ISSN 0892-7022
Publisher:
Taylor & Francis
Research Org:
Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY mica; uranium; surface charge; electrolyte