Isotopic Fractionation and Overall Permeation of Lithium by a Thin-Film Composite Polyamide Reverse Osmosis Membrane
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.
T. M. Whitworth et al., "Isotopic Fractionation and Overall Permeation of Lithium by a Thin-Film Composite Polyamide Reverse Osmosis Membrane," Journal of Membrane Science, vol. 88, no. 1-3, pp. 231-241, Elsevier, Mar 1994.
The definitive version is available at https://doi.org/10.1016/0376-7388(94)87009-8
Geosciences and Geological and Petroleum Engineering
Keywords and Phrases
Flat-Leaf Cell; Isotopic Fractionation; Lithium Chloride; Reverse Osmosis; Thin-Film Composite Membrane; Membrane Structures; Permeability; Lithium Compounds; Polymeric Membranes; Solute Rejection
International Standard Serial Number (ISSN)
Article - Journal
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