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Title: Modeling electrokinetics in ionic liquids: General

Abstract

Using direct numerical simulations, we provide a thorough study regarding the electrokinetics of ionic liquids. In particular, modified Poisson–Nernst–Planck equations are solved to capture the crowding and overscreening effects characteristic of an ionic liquid. For modeling electrokinetic flows in an ionic liquid, the modified Poisson-Nernst-Planck equations are coupled with Navier–Stokes equations to study the coupling of ion transport, hydrodynamics, and electrostatic forces. Specifically, we consider the ion transport between two parallel charged surfaces, charging dynamics in a nanopore, capacitance of electric double-layer capacitors, electroosmotic flow in a nanochannel, electroconvective instability on a plane ion-selective surface, and electroconvective flow on a curved ionselective surface. Lastly, we also discuss how crowding and overscreening and their interplay affect the electrokinetic behaviors of ionic liquids in these application problems.

Authors:
 [1];  [2];  [3];  [1]
  1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Physical and Computational Science Directorate
  2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Energy and Environment Directorate
  3. Univ. of Wisconsin-Madison, Madison, WI (United States). Dept. of Mechanical Engineering
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE Office of Fossil Energy (FE); USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR) (SC-21)
OSTI Identifier:
1357059
Alternate Identifier(s):
OSTI ID: 1401767
Report Number(s):
PNNL-SA-121684
Journal ID: ISSN 0173-0835
Grant/Contract Number:
AC05-76RL01830; 325038
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Electrophoresis (Weinheim)
Additional Journal Information:
Journal Name: Electrophoresis (Weinheim); Journal Volume: 38; Journal Issue: 13-14; Journal ID: ISSN 0173-0835
Country of Publication:
United States
Language:
English
Subject:
97 MATHEMATICS AND COMPUTING; 42 ENGINEERING; Electroconvective flow; Electrokinetics; Ionic liquids; Modified Poisson-Nernst-Planck equations

Citation Formats

Wang, Chao, Bao, Jie, Pan, Wenxiao, and Sun, Xin. Modeling electrokinetics in ionic liquids: General. United States: N. p., 2017. Web. doi:10.1002/elps.201600455.
Wang, Chao, Bao, Jie, Pan, Wenxiao, & Sun, Xin. Modeling electrokinetics in ionic liquids: General. United States. doi:10.1002/elps.201600455.
Wang, Chao, Bao, Jie, Pan, Wenxiao, and Sun, Xin. Sat . "Modeling electrokinetics in ionic liquids: General". United States. doi:10.1002/elps.201600455. https://www.osti.gov/servlets/purl/1357059.
@article{osti_1357059,
title = {Modeling electrokinetics in ionic liquids: General},
author = {Wang, Chao and Bao, Jie and Pan, Wenxiao and Sun, Xin},
abstractNote = {Using direct numerical simulations, we provide a thorough study regarding the electrokinetics of ionic liquids. In particular, modified Poisson–Nernst–Planck equations are solved to capture the crowding and overscreening effects characteristic of an ionic liquid. For modeling electrokinetic flows in an ionic liquid, the modified Poisson-Nernst-Planck equations are coupled with Navier–Stokes equations to study the coupling of ion transport, hydrodynamics, and electrostatic forces. Specifically, we consider the ion transport between two parallel charged surfaces, charging dynamics in a nanopore, capacitance of electric double-layer capacitors, electroosmotic flow in a nanochannel, electroconvective instability on a plane ion-selective surface, and electroconvective flow on a curved ionselective surface. Lastly, we also discuss how crowding and overscreening and their interplay affect the electrokinetic behaviors of ionic liquids in these application problems.},
doi = {10.1002/elps.201600455},
journal = {Electrophoresis (Weinheim)},
number = 13-14,
volume = 38,
place = {United States},
year = {Sat Apr 01 00:00:00 EDT 2017},
month = {Sat Apr 01 00:00:00 EDT 2017}
}

Journal Article:
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  • Using direct numerical simulations we provide a thorough study on the electrokinetics of ionic liquids. In particular, the modfied Poisson-Nernst-Planck (MPNP) equations are solved to capture the crowding and overscreening effects that are the characteristics of an ionic liquid. For modeling electrokinetic flows in an ionic liquid, the MPNP equations are coupled with the Navier-Stokes equations to study the coupling of ion transport, hydrodynamics, and electrostatic forces. Specifically, we consider the ion transport between two parallel plates, charging dynamics in a 2D straight-walled pore, electro-osmotic ow in a nano-channel, electroconvective instability on a plane ion-selective surface, and electroconvective ow onmore » a curved ion-selective surface. We discuss how the crowding and overscreening effects and their interplay affect the electrokinetic behaviors of ionic liquids in these application problems.« less
  • Given the difficulty of obtaining analytical solutions for the diffusion of interacting geminate pairs of (ion) radicals in liquids, it is common, following the original treatment of Mozumder, to 'prescribe' this diffusion. A demonstration is given that such a prescription is impossible for any interaction potential other than the Coulomb potential. This demonstration suggests the inadequacy of this common approach to modeling geminate pair and spur dynamics in the largest emerging class of organic solvents: room-temperature ionic liquids.
  • The transfer of strontium ion from acidic nitrate media into a series of 1-alkyl-3-methylimidazolium-based room-temperature ionic liquids containing dicyclohexano-18-crown-6 is shown to proceed via cation-exchange, in contrast to conventional solvents such as alkan-1-ols, in which extraction of a strontium nitrato-crown ether complex is observed.
  • A new class of task-specific ionic liquids (TSILs) based on the covalent attachment of imidazolium cations to a monoaza-crown ether fragment has been synthesized and characterized. The efficacy of these TSILs for the biphasic extraction of Cs(+) and Sr(2+) from aqueous solutions has been evaluated. The extraction properties of these TSILs can be influenced by the structures of the covalently attached imidazolium cations, which highlight the possibilities to enhance or tune the selectivities of crown ethers toward target ionic species through the covalent coupling with the imidazolium cations. (c) 2005 Elsevier B.V. All rights reserved.