Coion exclusion properties of cation exchange membranes in 2:1 divalent salt solutions
The selectivity of ion exchange membranes hinges on their capacity to exclude coions. Yet, understanding how they reject coions in multivalent salt solutions remains challenging. This study presents a new molecular theory to understand coion exclusion. It examines counterion and coion condensation,...
| Main Authors: | , , , , |
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| Other Authors: | |
| Format: | Journal Article |
| Language: | English |
| Published: |
2024
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| Subjects: | |
| Online Access: | https://hdl.handle.net/10356/180226 |
| _version_ | 1824454139657060352 |
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| author | Lim, Zheng Jie Kho, Marcus Toh, William Chen, Xiao Goh, K. B. |
| author2 | School of Mechanical and Aerospace Engineering |
| author_facet | School of Mechanical and Aerospace Engineering Lim, Zheng Jie Kho, Marcus Toh, William Chen, Xiao Goh, K. B. |
| author_sort | Lim, Zheng Jie |
| collection | NTU |
| description | The selectivity of ion exchange membranes hinges on their capacity to exclude coions. Yet, understanding how they reject coions in multivalent salt solutions remains challenging. This study presents a new molecular theory to understand coion exclusion. It examines counterion and coion condensation, including electrosteric effects. Supported by experimental data [Gokturk et al., Nat. Commun., 13 (2022)], we analyze cation exchange membrane potential in a 2:1 salt solution, revealing insights into coion selectivity and exclusion mechanisms. Notably, our theory deviates from earlier research by accommodating condensed divalent counterions that bind to one or two fixed-charged monomers. Additionally, we account for many-body electrostatic interactions, allowing the former to bind to sorbed coions. Our findings highlight the importance of coion condensation, especially in low-concentration salt conditions where coions are mainly condensed. This effect becomes less significant as the external solution concentration rises. These findings clarify the suitability of the ideal Donnan model in high-concentration salts, but its accuracy decreases in low-concentration situations. To summarize, our study emphasizes the need to account for counterion and coion condensation to understand membrane selectivity in low-concentration multivalent salt solutions. |
| first_indexed | 2025-02-19T03:17:34Z |
| format | Journal Article |
| id | ntu-10356/180226 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2025-02-19T03:17:34Z |
| publishDate | 2024 |
| record_format | dspace |
| spelling | ntu-10356/1802262024-09-28T16:48:29Z Coion exclusion properties of cation exchange membranes in 2:1 divalent salt solutions Lim, Zheng Jie Kho, Marcus Toh, William Chen, Xiao Goh, K. B. School of Mechanical and Aerospace Engineering Engineering Coion Condensation The selectivity of ion exchange membranes hinges on their capacity to exclude coions. Yet, understanding how they reject coions in multivalent salt solutions remains challenging. This study presents a new molecular theory to understand coion exclusion. It examines counterion and coion condensation, including electrosteric effects. Supported by experimental data [Gokturk et al., Nat. Commun., 13 (2022)], we analyze cation exchange membrane potential in a 2:1 salt solution, revealing insights into coion selectivity and exclusion mechanisms. Notably, our theory deviates from earlier research by accommodating condensed divalent counterions that bind to one or two fixed-charged monomers. Additionally, we account for many-body electrostatic interactions, allowing the former to bind to sorbed coions. Our findings highlight the importance of coion condensation, especially in low-concentration salt conditions where coions are mainly condensed. This effect becomes less significant as the external solution concentration rises. These findings clarify the suitability of the ideal Donnan model in high-concentration salts, but its accuracy decreases in low-concentration situations. To summarize, our study emphasizes the need to account for counterion and coion condensation to understand membrane selectivity in low-concentration multivalent salt solutions. Published version K.B. Goh received support from the Ministry of Higher Education through the Fundamental Research Grant Scheme (FRGS/1/2023/ STG07/MUSM/03/2), as well as the Monash University Malaysia Seed Grant (SED-000052). Xiao Chen's research was funded by the National Natural Science Foundation of China (No. 12202247), and the Postdoctoral International Exchange Program (funded by China Postdoc Council). 2024-09-25T00:57:32Z 2024-09-25T00:57:32Z 2024 Journal Article Lim, Z. J., Kho, M., Toh, W., Chen, X. & Goh, K. B. (2024). Coion exclusion properties of cation exchange membranes in 2:1 divalent salt solutions. Desalination, 574, 117179-. https://dx.doi.org/10.1016/j.desal.2023.117179 0011-9164 https://hdl.handle.net/10356/180226 10.1016/j.desal.2023.117179 2-s2.0-85181825001 574 117179 en Desalination © 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/bync-nd/4.0/). application/pdf |
| spellingShingle | Engineering Coion Condensation Lim, Zheng Jie Kho, Marcus Toh, William Chen, Xiao Goh, K. B. Coion exclusion properties of cation exchange membranes in 2:1 divalent salt solutions |
| title | Coion exclusion properties of cation exchange membranes in 2:1 divalent salt solutions |
| title_full | Coion exclusion properties of cation exchange membranes in 2:1 divalent salt solutions |
| title_fullStr | Coion exclusion properties of cation exchange membranes in 2:1 divalent salt solutions |
| title_full_unstemmed | Coion exclusion properties of cation exchange membranes in 2:1 divalent salt solutions |
| title_short | Coion exclusion properties of cation exchange membranes in 2:1 divalent salt solutions |
| title_sort | coion exclusion properties of cation exchange membranes in 2 1 divalent salt solutions |
| topic | Engineering Coion Condensation |
| url | https://hdl.handle.net/10356/180226 |
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