Title: Emerging investigator series: local pH effects on carbon oxidation in capacitive deionization architectures

Abstract

In this work, the effect of pH and potential is examined for the oxidation of carbon cloth electrodes used in capacitive deionization (CDI) processes. The degree of oxidation of the electrode surface, examined using the electrode's potential of zero charge (E_pzc) and measured using chronoamperometry and cyclic voltammetry, is found to be strongly correlated to the pH of the solution at the interface. Local pH measurements are examined at anodes and cathodes in full CDI and membrane-assisted capacitive deionization (MCDI) cells at cell voltages ranging from 0.3–1.2 V. The cathode is shown to be basic under charging potentials while the anode is found to be acidic. This local pH is found to be highly transient during charging and discharging in CDI cells while the pH is found to be relatively static in the MCDI cells, maintaining a basic pH at the cathode and an acidic pH at the anode even when the cell is discharged. Ion exchange membranes (IEM) are found to have two functions: (1) limiting co-ion expulsion that results from specific ion adsorption and (2) limiting the effects of parasitic Faradaic reactions on the separation process by stabilizing the local pH thereby mitigating dissolved oxygen reduction at themore » cathode and lessening carbon oxidation at the anode. Performance comparisons including the salt adsorption capacity and charge efficiency are also compared for these systems.« less

Authors:

Landon, James  ^[1];

• Search DOE PAGES for author "Landon, James"
• Search DOE PAGES for ORCID "0000-0001-8113-5166"

Gao, Xin  ^[1];

• Search DOE PAGES for author "Gao, Xin"
• Search DOE PAGES for ORCID "0000-0002-8865-1697"

Omosebi, Ayokunle  ^[1];

• Search DOE PAGES for author "Omosebi, Ayokunle"
• Search DOE PAGES for ORCID "0000-0003-0290-8736"

Liu, Kunlei ^[1]

---

+ Show Author Affiliations

1. Univ. of Kentucky, Lexington, KY (United States)

Publication Date:

Fri Mar 19 00:00:00 EDT 2021

Research Org.:

West Virginia Univ., Morgantown, WV (United States)

Sponsoring Org.:

USDOE Office of International Affairs (IA)

OSTI Identifier:

1850610

Alternate Identifier(s):

OSTI ID: 1772262

Grant/Contract Number:  

PI0000017

Resource Type:

Accepted Manuscript

Journal Name:

Environmental Science: Water Research & Technology

Additional Journal Information:

Journal Volume: 7; Journal Issue: 5; Journal ID: ISSN 2053-1400

Publisher:

Royal Society of Chemistry

Country of Publication:

United States

Language:

English

Subject:

54 ENVIRONMENTAL SCIENCES