Ion Separations Based on Spontaneously Arising Streaming Potentials in Rotating Isoporous Membranes
Highly selective ion separations are vital for producing pure salts, and membrane-based separations are promising alternatives to conventional ion-separation techniques. Our previous work demonstrated that simple pressure-driven flow through negatively charged isoporous membranes can separate Li<...
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-06-01
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| Series: | Membranes |
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| Online Access: | https://www.mdpi.com/2077-0375/12/6/631 |
| _version_ | 1797484492373360640 |
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| author | Chao Tang Andriy Yaroshchuk Merlin L. Bruening |
| author_facet | Chao Tang Andriy Yaroshchuk Merlin L. Bruening |
| author_sort | Chao Tang |
| collection | DOAJ |
| description | Highly selective ion separations are vital for producing pure salts, and membrane-based separations are promising alternatives to conventional ion-separation techniques. Our previous work demonstrated that simple pressure-driven flow through negatively charged isoporous membranes can separate Li<sup>+</sup> and K<sup>+</sup> with selectivities as high as 70 in dilute solutions. The separation mechanism relies on spontaneously arising streaming potentials that induce electromigration, which opposes advection and separates cations based on differences in their electrophoretic mobilities. Although the separation technique is simple, this work shows that high selectivities are possible only with careful consideration of experimental conditions including transmembrane pressure, solution ionic strength, the K<sup>+</sup>/Li<sup>+</sup> ratio in the feed, and the extent of concentration polarization. Separations conducted with a rotating membrane show Li<sup>+</sup>/K<sup>+</sup> selectivities as high as 150 with a 1000 rpm membrane rotation rate, but the selectivity decreases to 1.3 at 95 rpm. These results demonstrate the benefits and necessity of quantitative control of concentration polarization in highly selective separations. Increases in solution ionic strength or the K<sup>+</sup>/Li<sup>+</sup> feed ratio can also decrease selectivities more than an order of magnitude. |
| first_indexed | 2024-03-09T23:05:10Z |
| format | Article |
| id | doaj.art-a46b77d899ff48918c8ea9c9f33defd8 |
| institution | Directory Open Access Journal |
| issn | 2077-0375 |
| language | English |
| last_indexed | 2024-03-09T23:05:10Z |
| publishDate | 2022-06-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Membranes |
| spelling | doaj.art-a46b77d899ff48918c8ea9c9f33defd82023-11-23T17:55:08ZengMDPI AGMembranes2077-03752022-06-0112663110.3390/membranes12060631Ion Separations Based on Spontaneously Arising Streaming Potentials in Rotating Isoporous MembranesChao Tang0Andriy Yaroshchuk1Merlin L. Bruening2Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46656, USAICREA, pg.L.Companys 23, 08010 Barcelona, SpainDepartment of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46656, USAHighly selective ion separations are vital for producing pure salts, and membrane-based separations are promising alternatives to conventional ion-separation techniques. Our previous work demonstrated that simple pressure-driven flow through negatively charged isoporous membranes can separate Li<sup>+</sup> and K<sup>+</sup> with selectivities as high as 70 in dilute solutions. The separation mechanism relies on spontaneously arising streaming potentials that induce electromigration, which opposes advection and separates cations based on differences in their electrophoretic mobilities. Although the separation technique is simple, this work shows that high selectivities are possible only with careful consideration of experimental conditions including transmembrane pressure, solution ionic strength, the K<sup>+</sup>/Li<sup>+</sup> ratio in the feed, and the extent of concentration polarization. Separations conducted with a rotating membrane show Li<sup>+</sup>/K<sup>+</sup> selectivities as high as 150 with a 1000 rpm membrane rotation rate, but the selectivity decreases to 1.3 at 95 rpm. These results demonstrate the benefits and necessity of quantitative control of concentration polarization in highly selective separations. Increases in solution ionic strength or the K<sup>+</sup>/Li<sup>+</sup> feed ratio can also decrease selectivities more than an order of magnitude.https://www.mdpi.com/2077-0375/12/6/631streaming potentialion separationsselectivity |
| spellingShingle | Chao Tang Andriy Yaroshchuk Merlin L. Bruening Ion Separations Based on Spontaneously Arising Streaming Potentials in Rotating Isoporous Membranes Membranes streaming potential ion separations selectivity |
| title | Ion Separations Based on Spontaneously Arising Streaming Potentials in Rotating Isoporous Membranes |
| title_full | Ion Separations Based on Spontaneously Arising Streaming Potentials in Rotating Isoporous Membranes |
| title_fullStr | Ion Separations Based on Spontaneously Arising Streaming Potentials in Rotating Isoporous Membranes |
| title_full_unstemmed | Ion Separations Based on Spontaneously Arising Streaming Potentials in Rotating Isoporous Membranes |
| title_short | Ion Separations Based on Spontaneously Arising Streaming Potentials in Rotating Isoporous Membranes |
| title_sort | ion separations based on spontaneously arising streaming potentials in rotating isoporous membranes |
| topic | streaming potential ion separations selectivity |
| url | https://www.mdpi.com/2077-0375/12/6/631 |
| work_keys_str_mv | AT chaotang ionseparationsbasedonspontaneouslyarisingstreamingpotentialsinrotatingisoporousmembranes AT andriyyaroshchuk ionseparationsbasedonspontaneouslyarisingstreamingpotentialsinrotatingisoporousmembranes AT merlinlbruening ionseparationsbasedonspontaneouslyarisingstreamingpotentialsinrotatingisoporousmembranes |