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Title: One- and Two-Equation Models to Simulate Ion Transport in Charged Porous Electrodes

Abstract

Energy storage in porous capacitor materials, capacitive deionization (CDI) for water desalination, capacitive energy generation, geophysical applications, and removal of heavy ions from wastewater streams are some examples of processes where understanding of ionic transport processes in charged porous media is very important. In this work, one- and two-equation models are derived to simulate ionic transport processes in heterogeneous porous media comprising two different pore sizes. It is based on a theory for capacitive charging by ideally polarizable porous electrodes without Faradaic reactions or specific adsorption of ions. A two-step volume averaging technique is used to derive the averaged transport equations for multi-ionic systems without any further assumptions, such as thin electrical double layers or Donnan equilibrium. A comparison between both models is presented. The effective transport parameters for isotropic porous media are calculated by solving the corresponding closure problems. An approximate analytical procedure is proposed to solve the closure problems. Numerical and theoretical calculations show that the approximate analytical procedure yields adequate solutions. Lastly, a theoretical analysis shows that the value of interphase pseudo-transport coefficients determines which model to use.

Authors:
 [1]; ORCiD logo [2]
  1. Prairie View A&M Univ., Prairie View, TX (United State). Dept. of Chemical Engineering
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1422528
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Colloids and Interfaces
Additional Journal Information:
Journal Volume: 2; Journal Issue: 1; Journal ID: ISSN 2504-5377
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE; 36 MATERIALS SCIENCE; CDI; volume average; porous media; two-equation models

Citation Formats

Gabitto, Jorge, and Tsouris, Costas. One- and Two-Equation Models to Simulate Ion Transport in Charged Porous Electrodes. United States: N. p., 2018. Web. doi:10.3390/colloids2010004.
Gabitto, Jorge, & Tsouris, Costas. One- and Two-Equation Models to Simulate Ion Transport in Charged Porous Electrodes. United States. doi:10.3390/colloids2010004.
Gabitto, Jorge, and Tsouris, Costas. Fri . "One- and Two-Equation Models to Simulate Ion Transport in Charged Porous Electrodes". United States. doi:10.3390/colloids2010004. https://www.osti.gov/servlets/purl/1422528.
@article{osti_1422528,
title = {One- and Two-Equation Models to Simulate Ion Transport in Charged Porous Electrodes},
author = {Gabitto, Jorge and Tsouris, Costas},
abstractNote = {Energy storage in porous capacitor materials, capacitive deionization (CDI) for water desalination, capacitive energy generation, geophysical applications, and removal of heavy ions from wastewater streams are some examples of processes where understanding of ionic transport processes in charged porous media is very important. In this work, one- and two-equation models are derived to simulate ionic transport processes in heterogeneous porous media comprising two different pore sizes. It is based on a theory for capacitive charging by ideally polarizable porous electrodes without Faradaic reactions or specific adsorption of ions. A two-step volume averaging technique is used to derive the averaged transport equations for multi-ionic systems without any further assumptions, such as thin electrical double layers or Donnan equilibrium. A comparison between both models is presented. The effective transport parameters for isotropic porous media are calculated by solving the corresponding closure problems. An approximate analytical procedure is proposed to solve the closure problems. Numerical and theoretical calculations show that the approximate analytical procedure yields adequate solutions. Lastly, a theoretical analysis shows that the value of interphase pseudo-transport coefficients determines which model to use.},
doi = {10.3390/colloids2010004},
journal = {Colloids and Interfaces},
number = 1,
volume = 2,
place = {United States},
year = {Fri Jan 19 00:00:00 EST 2018},
month = {Fri Jan 19 00:00:00 EST 2018}
}

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