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Title: Structure and transport of aqueous electrolytes: From simple halides to radionuclide ions

Molecular simulations are used to compare the structure and dynamics of conventional and radioactive aqueous electrolytes: chloride solutions with sodium, potassium, cesium, calcium, and strontium. The study of Cs{sup +} and Sr{sup 2+} is important because these radioactive ions can be extremely harmful and are often confused by living organisms for K{sup +} and Ca{sup 2+}, respectively. Na{sup +}, Ca{sup 2+}, and Sr{sup 2+} are strongly bonded to their hydration shell because of their large charge density. We find that the water molecules in the first hydration shell around Na{sup +} form hydrogen bonds between each other, whereas molecules in the first hydration shell around Ca{sup 2+} and Sr{sup 2+} predominantly form hydrogen bonds with water molecules in the second shell. In contrast to these three ions, K{sup +} and Cs{sup +} have low charge densities so that they are weakly bonded to their hydration shell. Overall, the structural differences between Ca{sup 2+} and Sr{sup 2+} are small, but the difference between their coordination numbers relative to their surface areas could potentially be used to separate these ions. Moreover, the different decays of the velocity-autocorrelation functions corresponding to these ions indicates that the difference in mass could be used tomore » separate these cations. In this work, we also propose a new definition of the pairing time that is easy to calculate and of physical significance regardless of the problem at hand.« less
Authors:
;  [1] ;  [2]
  1. Institut Charles Gerhardt Montpellier, CNRS (UMR 5253), Université Montpellier 2, ENSCM, 8 rue de l’Ecole Normale, 34296 Montpellier Cedex 05 (France)
  2. (UMI 3466), Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139 (United States)
Publication Date:
OSTI Identifier:
22308240
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 141; Journal Issue: 12; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CALCIUM; CALCIUM IONS; CATIONS; CESIUM; CESIUM IONS; CHARGE DENSITY; ELECTROLYTES; HYDRATION; HYDROGEN; MOLECULES; POTASSIUM; POTASSIUM IONS; SIMULATION; SODIUM; SODIUM IONS; STRONTIUM; STRONTIUM IONS; SURFACE AREA