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Solvent‐Polymeric Membranes for Separation of Li + From Other Alkali Metal and Alkaline Earth Ions
Author(s) -
JagurGrodzinski Joseph,
Schori Ehud
Publication year - 1985
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.198500070
Subject(s) - chemistry , membrane , alkali metal , inorganic chemistry , alkaline earth metal , selectivity , permeation , solvent , ion , metal ions in aqueous solution , ion exchange , lithium (medication) , separation process , chromatography , organic chemistry , catalysis , medicine , biochemistry , endocrinology
Lithium may be recovered from the Dead Sea brines by a process which combines membrane separation with ion‐exchange. Solvent‐polymeric membranes based on alkyl‐arylphosphates cause selective permeation of lithium ions with Br − 3 as counter ions. Addition of the derivatives of neutral “crown” ethers did not improve their performance and an adverse effect, due to the decrease in the fluidity of the membrane system, was observed. Incorporation of ionizable “crown” ethers compatible with the system may, however, be advantageous; pH gradients could act as a driving force for transport of lithium in such systems. Membranes prepared with (2‐ethylhexyl)‐diphenyl phosphate (Santicizer 141) gave the best results from the point of view of selectivity of Li + transport vs. Mg 2+ and Ca 2+ . Maintenance of ca. 10 −3 M concentrations of Br 2 in the end‐brine solutions gives optimal membrane performance. No significant change in membrane permeability and selectivity occurred during six months of their operation. Lithium ions in the product solution of the membrane separation process may be further separated from the residual Mg 2+ and Ca 2+ ions and concentrated up to 1 M by ion exchange processes. Lithium may be precipitated from such solutions, free from alkaline earth ions, as Li 2 CO 3 .