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Title: Two-Dimensional Porous Electrode Model for Capacitive Deionization

Authors:
; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1411685
Report Number(s):
LLNL-JRNL-735859
Grant/Contract Number:
AC52-07NA27344
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
The Journal of Physical Chemistry C, vol. 119, no. 44, October 28, 2015, pp. 24681-24694
Additional Journal Information:
Journal Name: The Journal of Physical Chemistry C, vol. 119, no. 44, October 28, 2015, pp. 24681-24694
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY

Citation Formats

Hemmatifar, A, Stadermann, M, and Santiago, J G. Two-Dimensional Porous Electrode Model for Capacitive Deionization. United States: N. p., 2017. Web.
Hemmatifar, A, Stadermann, M, & Santiago, J G. Two-Dimensional Porous Electrode Model for Capacitive Deionization. United States.
Hemmatifar, A, Stadermann, M, and Santiago, J G. 2017. "Two-Dimensional Porous Electrode Model for Capacitive Deionization". United States. doi:. https://www.osti.gov/servlets/purl/1411685.
@article{osti_1411685,
title = {Two-Dimensional Porous Electrode Model for Capacitive Deionization},
author = {Hemmatifar, A and Stadermann, M and Santiago, J G},
abstractNote = {},
doi = {},
journal = {The Journal of Physical Chemistry C, vol. 119, no. 44, October 28, 2015, pp. 24681-24694},
number = ,
volume = ,
place = {United States},
year = 2017,
month = 7
}

Journal Article:
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  • Flow electrode deionization (FCDI) is an emerging area for continuous and scalable deionization, but the electrochemical and flow properties of the flow electrode need to be improved to minimize energy consumption. We examine chemical oxidation of granular activated carbon (AC) here to study the role of surface heteroatoms on rheology and electrochemical performance of a flow electrode (carbon slurry) for deionization processes. Moreover, it was demonstrated that higher mass densities could be used without increasing energy for pumping when using oxidized active material. High mass-loaded flow electrodes (28% carbon content) based on oxidized AC displayed similar viscosities (~21 Pa s)more » to lower mass-loaded flow electrodes (20% carbon content) based on nonoxidized AC. The 40% increased mass loading (from 20% to 28%) resulted in a 25% increase in flow electrode gravimetric capacitance (from 65 to 83 F g –1) without sacrificing flowability (viscosity). The electrical energy required to remove ~18% of the ions (desalt) from of the feed solution was observed to be significantly dependent on the mass loading and decreased (~60%) from 92 ± 7 to 28 ± 2.7 J with increased mass densities from 5 to 23 wt %. Finally, it is shown that the surface chemistry of the active material in a flow electrode effects the electrical and pumping energy requirements of a FCDI system.« less
  • Carbon electrodes for desalination purpose have been successfully synthesized using activated carbon powder (BET surface area=700 – 1400 m{sup 2}/g), carbon black and polyvinyl alcohol (PVA) binder by cross-linking method with glutaric acid (GA) at 120 °C. The electrochemical properties of the carbon electrodes were analyzed using electrical impedance spectroscopy (EIS) and cyclic voltammetry (CV) whilst the physical properties were observed with scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX). In order to assess the desalting performance, salt removal experiments were performed by constructing a capacitive deionization unit cell with five pairs of carbon electrodes. For each pair consistedmore » of two parallel carbon electrodes separated by a spacer. Desalination and regeneration processes were also observed in the salt-removal experiments. The salt-removal experiments were carried out in single-pass mode using a solution with 0.1 M NaCl at a flow rate of 10 mL/min. A voltage of 3 V was applied to the cell for 60 minutes for both processes in desalination and regeneration. The result showed that the percentage value of the salt-removal was achieved at 20%.« less
  • Ion storage in porous electrodes is important in applications such as energy storage by supercapacitors, water purification by capacitive deionization, extraction of energy from a salinity difference and heavy ion purification. In this paper, a model is presented to simulate the charge process in homogeneous porous media comprising big pores. It is based on a theory for capacitive charging by ideally polarizable porous electrodes without faradaic reactions or specific adsorption of ions. A volume averaging technique is used to derive the averaged transport equations in the limit of thin electrical double layers. Transport between the electrolyte solution and the chargedmore » wall is described using the Gouy–Chapman–Stern model. The effective transport parameters for isotropic porous media are calculated solving the corresponding closure problems. Finally, the source terms that appear in the average equations are calculated using numerical computations. An alternative way to deal with the source terms is proposed.« less