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Single-ion Hydration and Ion Association in Aqueous Solutions

Shi, Yu
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439310243

Abstract Details

2015, PhD, University of Cincinnati, Arts and Sciences: Physics.
The research has focused on three projects: 1) fundamental thermodynamics aspects of ion hydration; 2) the driving forces for ion pair association; 3) a phase diagram calculation of the binary system consisting of water and 1-butanol using free energy methods developed in 1) and 2). First, the single ion hydration free energy is computed by quasi-chemical theory. An issue is that a Gaussian model fails to estimate the anion long-ranged contribution at intermediate cavity sizes; this issue is represented and addressed by the midpoint rule. It is found that the work of growing a cavity to a 6.15 Angstrom. A size is equal to minus the ions’ bulk hydration free energy, suggesting that a consistent shift of ± 11.6 kcal/mol (across the alkali halide series) arises due to the net potential at the center of this cavity. Second, the local molecular field theory is employed to partition the potential of mean force of ion pairs. The association behavior of ion pairs is shown to be in line with the law of matching water affinity, and the local electrostatic contribution is seen to provide ion specificity. Correlation of the local electrostatic contribution with the coordination number is presented. Third, a calculation method for a binary mixture phase diagram is developed in the context of the potential distribution theorem. The quasi-chemical theory is used to estimate the hydration free energy of probe water molecules. Through the Gibbs-Duhem equation, the activity coefficients of both water and 1-butanol can be obtained. The subsequent optimization of an empirical excess Gibbs model produces the Gibbs energy profile over all the concentrations, and its double-tangent points locate the phase boundaries.
Thomas Beck, Ph.D. (Committee Chair)
Howard Everett Jackson, Ph.D. (Committee Member)
Rostislav Serota, Ph.D. (Committee Member)
L.C.R. Wijewardhana, Ph.D. (Committee Member)
103 p.
Physical Chemistry
Hydration Free Energy; Molecular Dynamics; Phase Diagram

Recommended Citations

Citations

  • Shi, Y. (2015). Single-ion Hydration and Ion Association in Aqueous Solutions [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439310243

    APA Style (7th edition)

  • Shi, Yu. Single-ion Hydration and Ion Association in Aqueous Solutions. 2015. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439310243.

    MLA Style (8th edition)

  • Shi, Yu. "Single-ion Hydration and Ion Association in Aqueous Solutions." Doctoral dissertation, University of Cincinnati, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439310243

    Chicago Manual of Style (17th edition)

ucin1439310243
584
© 2015, some rights reserved.Creative Commons License Single-ion Hydration and Ion Association in Aqueous Solutions by Yu Shi is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by University of Cincinnati and OhioLINK.