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Title: Partitioning of oxygen isotopes during the aqueous solvation of nitric acid

Abstract

Mixtures of water and inorganic acids show differences in isotopic composition between the vapor and liquid phases, reportedly even at an azeotrope. A recent reactive azeotropy analysis rationalized this by allowing for differences in stable isotope composition between bound solvation complexes and the bulk liquid. In this study, a mixture of water and nitric acid was examined experimentally to determine whether or not significant differences in stable isotope composition exist between bound solvation complexes and the bulk solution. A Rayleigh distillation was conducted using a solution of nitric acid and water. During the distillation, it was expected that bulk water would be vaporized first while (bound) water involved with hydrating the acid would be vaporized at later times along with the acid. Samples of both distillate and residual liquid were collected over time intervals and analyzed to determine oxygen and nitrogen stable isotope composition using isotope ratio mass spectrometry. Comparative samples were collected from the distillation of water alone. The measured oxygen fractionation factors suggest that the acid is preferentially hydrated with 18O-enriched water, compared to the unbound, or bulk, water. Preferential coordination of 18O-enriched water with the dissolved acid is consistent with heavier water forming stronger bonds relative tomore » light water. Here, the results imply that isotope-dependent partitioning between bulk solvent and dissolved complexes may prove necessary in developing accurate descriptions of isotope fractionation during vapor-liquid equilibrium.« less

Authors:
 [1]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [2]
  1. Univ. of Texas at Austin, Austin, TX (United States)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Laboratory Directed Research and Development (LDRD) Program
OSTI Identifier:
1572331
Report Number(s):
LA-UR-19-25191
Journal ID: ISSN 0378-3812
Grant/Contract Number:  
89233218CNA000001
Resource Type:
Accepted Manuscript
Journal Name:
Fluid Phase Equilibria
Additional Journal Information:
Journal Name: Fluid Phase Equilibria; Journal ID: ISSN 0378-3812
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
oxygen isotopes; Nitric acid-water; Stable isotope fractionation

Citation Formats

Larson, Toti E., Perkins, George B., Williams, Robert F., Fessenden, Julianna E., Clegg, Samuel M., and Currier, Robert P. Partitioning of oxygen isotopes during the aqueous solvation of nitric acid. United States: N. p., 2019. Web. doi:10.1016/j.fluid.2019.112364.
Larson, Toti E., Perkins, George B., Williams, Robert F., Fessenden, Julianna E., Clegg, Samuel M., & Currier, Robert P. Partitioning of oxygen isotopes during the aqueous solvation of nitric acid. United States. doi:10.1016/j.fluid.2019.112364.
Larson, Toti E., Perkins, George B., Williams, Robert F., Fessenden, Julianna E., Clegg, Samuel M., and Currier, Robert P. Thu . "Partitioning of oxygen isotopes during the aqueous solvation of nitric acid". United States. doi:10.1016/j.fluid.2019.112364.
@article{osti_1572331,
title = {Partitioning of oxygen isotopes during the aqueous solvation of nitric acid},
author = {Larson, Toti E. and Perkins, George B. and Williams, Robert F. and Fessenden, Julianna E. and Clegg, Samuel M. and Currier, Robert P.},
abstractNote = {Mixtures of water and inorganic acids show differences in isotopic composition between the vapor and liquid phases, reportedly even at an azeotrope. A recent reactive azeotropy analysis rationalized this by allowing for differences in stable isotope composition between bound solvation complexes and the bulk liquid. In this study, a mixture of water and nitric acid was examined experimentally to determine whether or not significant differences in stable isotope composition exist between bound solvation complexes and the bulk solution. A Rayleigh distillation was conducted using a solution of nitric acid and water. During the distillation, it was expected that bulk water would be vaporized first while (bound) water involved with hydrating the acid would be vaporized at later times along with the acid. Samples of both distillate and residual liquid were collected over time intervals and analyzed to determine oxygen and nitrogen stable isotope composition using isotope ratio mass spectrometry. Comparative samples were collected from the distillation of water alone. The measured oxygen fractionation factors suggest that the acid is preferentially hydrated with 18O-enriched water, compared to the unbound, or bulk, water. Preferential coordination of 18O-enriched water with the dissolved acid is consistent with heavier water forming stronger bonds relative to light water. Here, the results imply that isotope-dependent partitioning between bulk solvent and dissolved complexes may prove necessary in developing accurate descriptions of isotope fractionation during vapor-liquid equilibrium.},
doi = {10.1016/j.fluid.2019.112364},
journal = {Fluid Phase Equilibria},
number = ,
volume = ,
place = {United States},
year = {2019},
month = {10}
}

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This content will become publicly available on October 17, 2020
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