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New cation‐exchange membranes for hyperfiltration processes
Author(s) -
Van Der Velden P. M.,
Smolders C. A.
Publication year - 1977
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1977.070210601
Subject(s) - membrane , polymer chemistry , chemistry , copolymer , ultrafiltration (renal) , aqueous solution , isocyanate , chemical engineering , organic chemistry , polymer , chromatography , polyurethane , biochemistry , engineering
A new route for the preparation of cation exchange membranes from polystyrene–polyisoprene–polystyrene (SIS) block copolymers has been studied, using N‐chlorosulfonyl isocyanate. At temperatures of 0° to 20°C, N‐chlorosulfonyl isocyanate reacts readily with the olefin group in polyisoprenes, resulting in a β‐lactam‐N‐sulfonyl chloride group. Films of this product can be cast which are hydrolyzed afterwards with aqueous ammonia at room temperature to give a membrane with ionic sulfonate and neutral carbamoyl groups. Homogeneous membranes are prepared with an SIS block copolymer as starting material and with mole ratios of N‐chlorosulfonyl isocyanate/isoprene between 15% and 45%. In hyperfiltration experiments at 40 atmospheres, both NaCl and Na 2 SO 4 are rejected up to 82%, while fluxes of 0.25 to 0.30 cm 3 /cm 2 ·hr are obtained. From permeation and hyperfiltration experiments, it is concluded that the weight fraction of membrane water has a large influence on the flux. The water content in the membrane during the hyperfiltration process is primarily determined by the applied pressure, the type of salt, and its concentration.