Tuning initial pH to decrease salt ion transport in saltwater electrolysis

Thin-film composite membranes are being studied as replacements to more expensive ion exchange membranes in saltwater electrolysis for carbon neutral hydrogen production. However, a persistent challenge is transport of salt ions between a contained anolyte and saltwater catholyte rather than water i...

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Main Authors: Rachel F. Taylor, Fernan Martinez-Jimenez, Bruce E. Logan
Format: Article
Language:English
Published: Elsevier 2025-02-01
Series:Electrochemistry Communications
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Online Access:http://www.sciencedirect.com/science/article/pii/S1388248124002017
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author Rachel F. Taylor
Fernan Martinez-Jimenez
Bruce E. Logan
author_facet Rachel F. Taylor
Fernan Martinez-Jimenez
Bruce E. Logan
author_sort Rachel F. Taylor
collection DOAJ
description Thin-film composite membranes are being studied as replacements to more expensive ion exchange membranes in saltwater electrolysis for carbon neutral hydrogen production. However, a persistent challenge is transport of salt ions between a contained anolyte and saltwater catholyte rather than water ions (H+, OH−). We used a validated Nernst Planck ion transport model in COMSOL Multiphysics to simulate how the initial electrolyte pH impacts total salt ion transport within the first two hours of electrolysis, when the greatest percentage of salts cross the membrane. At fixed current densities of 10 mA cm−2 and 100 mA cm−2, setting an initial anolyte pH to 0 (rather than using a neutral pH) and catholyte pH of 14 achieved the goal of predominantly transporting water ions across the membrane, thereby accomplishing a substantial reduction in nitrate (substituting for chloride) ion transport. At the lower current density, setting the anolyte pH to 0 while leaving the catholyte pH neutral resulted in the same reduction of nitrate transport, with water ions carrying most of the charge. Thus, simply setting the solution initial conditions can substantially mitigate chloride ion transport from the catholyte to the anolyte, improving the feasibility of using saltwater electrolysis for green hydrogen production.
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spelling doaj-art-f4b0bad9840a4dc8a28eea964a87c42c2025-02-09T04:59:48ZengElsevierElectrochemistry Communications1388-24812025-02-01171107858Tuning initial pH to decrease salt ion transport in saltwater electrolysisRachel F. Taylor0Fernan Martinez-Jimenez1Bruce E. Logan2Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, USAEnvironmental Science & Engineering Program, King Abdullah University of Science and Technology, Thuwal, Saudi ArabiaDepartment of Chemical Engineering, The Pennsylvania State University, University Park, PA, USA; Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, PA, USA; Corresponding author at: Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, USA.Thin-film composite membranes are being studied as replacements to more expensive ion exchange membranes in saltwater electrolysis for carbon neutral hydrogen production. However, a persistent challenge is transport of salt ions between a contained anolyte and saltwater catholyte rather than water ions (H+, OH−). We used a validated Nernst Planck ion transport model in COMSOL Multiphysics to simulate how the initial electrolyte pH impacts total salt ion transport within the first two hours of electrolysis, when the greatest percentage of salts cross the membrane. At fixed current densities of 10 mA cm−2 and 100 mA cm−2, setting an initial anolyte pH to 0 (rather than using a neutral pH) and catholyte pH of 14 achieved the goal of predominantly transporting water ions across the membrane, thereby accomplishing a substantial reduction in nitrate (substituting for chloride) ion transport. At the lower current density, setting the anolyte pH to 0 while leaving the catholyte pH neutral resulted in the same reduction of nitrate transport, with water ions carrying most of the charge. Thus, simply setting the solution initial conditions can substantially mitigate chloride ion transport from the catholyte to the anolyte, improving the feasibility of using saltwater electrolysis for green hydrogen production.http://www.sciencedirect.com/science/article/pii/S1388248124002017Hydrogen productionThin film composite membranesPolyamide membranesNernst-Planck transport modellingElectrolyte pH
spellingShingle Rachel F. Taylor
Fernan Martinez-Jimenez
Bruce E. Logan
Tuning initial pH to decrease salt ion transport in saltwater electrolysis
Electrochemistry Communications
Hydrogen production
Thin film composite membranes
Polyamide membranes
Nernst-Planck transport modelling
Electrolyte pH
title Tuning initial pH to decrease salt ion transport in saltwater electrolysis
title_full Tuning initial pH to decrease salt ion transport in saltwater electrolysis
title_fullStr Tuning initial pH to decrease salt ion transport in saltwater electrolysis
title_full_unstemmed Tuning initial pH to decrease salt ion transport in saltwater electrolysis
title_short Tuning initial pH to decrease salt ion transport in saltwater electrolysis
title_sort tuning initial ph to decrease salt ion transport in saltwater electrolysis
topic Hydrogen production
Thin film composite membranes
Polyamide membranes
Nernst-Planck transport modelling
Electrolyte pH
url http://www.sciencedirect.com/science/article/pii/S1388248124002017
work_keys_str_mv AT rachelftaylor tuninginitialphtodecreasesaltiontransportinsaltwaterelectrolysis
AT fernanmartinezjimenez tuninginitialphtodecreasesaltiontransportinsaltwaterelectrolysis
AT bruceelogan tuninginitialphtodecreasesaltiontransportinsaltwaterelectrolysis