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Title: Reducing Chloride Ion Permeation during Seawater Electrolysis Using Double-Polyamide Thin-Film Composite Membranes
Low-cost polyamide thin-film composite membranes are being explored as alternatives to expensive cation exchange membranes for seawater electrolysis. However, chloride transport from seawater to the anode chamber must be reduced to minimize production of chlorine gas. A double-polyamide membrane composite structure was created that reduced chloride transport. Adding five polyamide layers on the back of a conventional polyamide composite membrane reduced chloride ion transport by 53% and did not increase the applied voltage. Decelerated chloride permeation was attributed to enhanced electrostatic and steric repulsion created by the new polyamide layer. Charge was balanced through increased sodium ion transport (52%) from the anolyte to the catholyte rather than a change in water ion transport. As a result, the Nernstian loss arising from the pH difference between the anolyte and catholyte remained relatively constant during electrolysis despite membrane modifications. This lack of a change in pH showed that transport of proton and hydroxide during electrolysis was independent of salt ion transport. Therefore, only sodium ion transport could compensate for the reduction of chloride flux to maintain the set current. Overall, these results prove the feasibility of using double-polyamide structure to control chloride permeation during seawater electrolysis without sacrificing energy consumption.  more » « less
Award ID(s):
2027552
PAR ID:
10526109
Author(s) / Creator(s):
; ; ; ; ;
Publisher / Repository:
American Chemical Society
Date Published:
Journal Name:
Environmental Science & Technology
Volume:
58
Issue:
1
ISSN:
0013-936X
Page Range / eLocation ID:
391 to 399
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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