Abstract
A small, but significant fractionation of lithium isotopes was observed during reverse osmosis experiments performed with a thin-film composite polyamide membrane (FilmTec FT-30 membrane). Relative to the feed solution, the heavier lithium isotope 7Li was depleted in the permeate from 4.3 to 10.6 per mil (±3.3 per mil) during six experimental runs. The observed isotopic fractionation might be the result of the slightly different permeabilities of 6Li and 7Li across the FT-30 membrane. The heavier of two solute isotopes has a slightly lower mobility due to its slightly greater mass. Therefore, the heavy isotope permeates slightly more slowly inside the membrane than its isotopically lighter counterpart. As a result, more of the heavier isotope is retained on the high-pressure side of the membrane during each run. The magnitude of isotopic fractionation generally increased with increasing water permeation rates. Additionally, experimental evidence shows that the FT-30 membrane exhibits essentially identical solute rejection with NaCl and LiCl under the same operating conditions.
Original language | English (US) |
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Pages (from-to) | 231-241 |
Number of pages | 11 |
Journal | Journal of Membrane Science |
Volume | 88 |
Issue number | 2-3 |
DOIs | |
State | Published - Mar 16 1994 |
Externally published | Yes |
Keywords
- Flat-leaf cell
- Isotopic fractionation
- Lithium chloride
- Reverse osmosis
- Thin-film composite membrane
ASJC Scopus subject areas
- Biochemistry
- General Materials Science
- Physical and Theoretical Chemistry
- Filtration and Separation