End-Member Formulation of Solid Solutions and Reactive Transport

Lichtner, Peter C.

doi:10.2172/1221523

Title: End-Member Formulation of Solid Solutions and Reactive Transport

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Abstract

A model for incorporating solid solutions into reactive transport equations is presented based on an end-member representation. Reactive transport equations are solved directly for the composition and bulk concentration of the solid solution. Reactions of a solid solution with an aqueous solution are formulated in terms of an overall stoichiometric reaction corresponding to a time-varying composition and exchange reactions, equivalent to reaction end-members. Reaction rates are treated kinetically using a transition state rate law for the overall reaction and a pseudo-kinetic rate law for exchange reactions. The composition of the solid solution at the onset of precipitation is assumed to correspond to the least soluble composition, equivalent to the composition at equilibrium. The stoichiometric saturation determines if the solid solution is super-saturated with respect to the aqueous solution. The method is implemented for a simple prototype batch reactor using Mathematica for a binary solid solution. Finally, the sensitivity of the results on the kinetic rate constant for a binary solid solution is investigated for reaction of an initially stoichiometric solid phase with an undersaturated aqueous solution.

Authors:

Lichtner, Peter C. ^[1]

Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

Publication Date:: Tue Sep 01 00:00:00 EDT 2015

Research Org.:: Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

Sponsoring Org.:: USDOE Office of Nuclear Energy (NE), Fuel Cycle Technologies (NE-5)

OSTI Identifier:: 1221523

Report Number(s):: SAND2015-7985
603870

DOE Contract Number:: AC04-94AL85000

Resource Type:: Technical Report

Country of Publication:: United States

Language:: English

Citation Formats


                    Lichtner, Peter C. End-Member Formulation of Solid Solutions and Reactive Transport.  United States: N. p., 2015. 
        Web.  doi:10.2172/1221523.

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                    Lichtner, Peter C. End-Member Formulation of Solid Solutions and Reactive Transport.  United States.  https://doi.org/10.2172/1221523

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                    Lichtner, Peter C. 2015.  
        "End-Member Formulation of Solid Solutions and Reactive Transport".  United States.  https://doi.org/10.2172/1221523.  https://www.osti.gov/servlets/purl/1221523.

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@article{osti_1221523,

  title        = {End-Member Formulation of Solid Solutions and Reactive Transport},

  author       = {Lichtner, Peter C.},

  abstractNote = {A model for incorporating solid solutions into reactive transport equations is presented based on an end-member representation. Reactive transport equations are solved directly for the composition and bulk concentration of the solid solution. Reactions of a solid solution with an aqueous solution are formulated in terms of an overall stoichiometric reaction corresponding to a time-varying composition and exchange reactions, equivalent to reaction end-members. Reaction rates are treated kinetically using a transition state rate law for the overall reaction and a pseudo-kinetic rate law for exchange reactions. The composition of the solid solution at the onset of precipitation is assumed to correspond to the least soluble composition, equivalent to the composition at equilibrium. The stoichiometric saturation determines if the solid solution is super-saturated with respect to the aqueous solution. The method is implemented for a simple prototype batch reactor using Mathematica for a binary solid solution. Finally, the sensitivity of the results on the kinetic rate constant for a binary solid solution is investigated for reaction of an initially stoichiometric solid phase with an undersaturated aqueous solution.},

  doi          = {10.2172/1221523},

  url          = {https://www.osti.gov/biblio/1221523},
  journal      = {},
number       = ,

  volume       = ,

  place        = {United States},

  year         = {Tue Sep 01 00:00:00 EDT 2015},

  month        = {Tue Sep 01 00:00:00 EDT 2015}

}

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