| 摘要 |
PURPOSE:To separate selectively A. a water soluble salt of a specific inorg.-basic acid by bringing said A. and B.>=1 kind of a specific water soluble org. compd. and a water soluble polyvalent metallic salt, etc. of an inorg.-basic acid into contact with a multiple-unit semipermeable membrane having a specific compsn. CONSTITUTION:An ultrathin film in which PVA and an amino compd. having >=2 secondary amino groups in one molecule are cross-linked and polymerized with a multifunctional cross-linking agent is provided on a porous base material and a porous layer consisting of water insoluble PVA is provided as an internal layer, by which a multiple-unit semipermeable membrane is formed. An aq. soln. contg. A. a water soluble alkali metallic salt or ammonium salt of an inorg.- basic acid and B.>=1 kind among a water soluble org. compd. of >=100mol.wt., a water soluble polyvalent metallic salt of an inorg.-basic acid and a water soluble metallic salt or ammonium salt of an inorg. polybasic acid is maintained under the pressure higher than the osmotic pressure thereof and is brought into the above-described multiple-unit membrane.
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