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Lookup NU author(s): Professor Ian MetcalfeORCiD
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).
© 2026 The Authors. While membrane-based CO2 capture is a promising technology for separating CO2 from low-concentration environments such as air, it is generally more energy-intensive than alternative separation methods like adsorption. The uphill diffusion of CO2, driven by the dissipation of the chemical potential difference of water, can potentially reduce the energy demand of membrane-based CO2 capture from dilute sources. In this analysis, we explore the coupling between CO2 flux and H2O's chemical potential gradient, hypothesizing that dissipation of H2O chemical potential gradients and CO2-selective sorption enable CO2 transport against its concentration gradient and even its chemical potential gradient. Through Onsager analysis and second-law thermodynamic evaluations, we demonstrate the feasibility of this mechanism under steady-state conditions from multiple perspectives, considering various thermodynamic and transport aspects. We also highlight how the level of CO2 enrichment from the diluted feed to the more concentrated permeate depends on the fraction of water free energy utilized to drive uphill CO2 diffusion. This analysis aims to provide a foundation and identify key targets for developing membrane materials and processes that are designed to exploit this coupling phenomenon.
Author(s): Jang I, Chen H, Metcalfe IS, Lively RP
Publication type: Article
Publication status: Published
Journal: Journal of Membrane Science
Year: 2026
Volume: 742
Print publication date: 01/03/2026
Online publication date: 11/01/2026
Acceptance date: 10/01/2026
Date deposited: 02/02/2026
ISSN (print): 0376-7388
ISSN (electronic): 1873-3123
Publisher: Elsevier BV
URL: https://doi.org/10.1016/j.memsci.2026.125153
DOI: 10.1016/j.memsci.2026.125153
Data Access Statement: Data will be made available on request.
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