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Studies on the effects of copper salts on the separation performance of chitosan membranes
Author(s) -
Wang XinPing,
Shen ZhiQuan
Publication year - 2000
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/1097-0126(200011)49:11<1426::aid-pi524>3.0.co;2-j
Subject(s) - chitosan , membrane , pervaporation , chemistry , permeation , copper , selectivity , ethanol , molecule , ionic bonding , polymer chemistry , inorganic chemistry , organic chemistry , nuclear chemistry , ion , catalysis , biochemistry
The effects of copper salts on the pervaporation performance of chitosan membranes for water/ethanol mixtures were studied. The results show that the selectivity to water can be improved by addition of Cu 2+ in the feed, and that CuSO 4 was more effective than CuCl 2 . The reason for the marked increase in selectivity and the difference in performance between the copper salts is explained as follows. With CuSO 4 , the multivalent metal ion forms a complex with four NH 2 ligands of the chitosan molecules and the new conformation is simultaneously immobilized by the ionic crosslinking with SO 4 2 . This is different from the Cu 2+ of CuCl 2 , which mainly coordinates with OH in the C‐6 position of chitosan, and Cl − cannot crosslink the complexes. Therefore, chitosan membranes have a stronger absorption capability for the Cu 2+ of CuSO 4 than for Cu 2+ from CuCl 2 . In addition, ion cross‐linking formed by CuSO 4 more strongly decreases the permeation of ethanol. Studies of the effects of acid on pervaporation performance of the Cu 2+ ‐treated chitosan membrane show that separation properties of the membrane change with addition of acid to the feed. This is attributed to Cu 2+ being eluted from the chitosan membrane followed by the reaction of acid molecules with the NH 2 functional groups of the chitosan membrane. © 2000 Society of Chemical Industry