In Situ Study of Diffusion and Interaction of Water and Mono- or Divalent Anions in a Positively Charged Membrane Using Two-Dimensional Correlation FT-IR/Attenuated Total Reflection Spectroscopy
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- 作者：Beibei Tang ; Peiyi Wu ; H. W. Siesler
- 刊名：Journal of Physical Chemistry B
- 出版年：2008
- 出版时间：March 13, 2008
- 年：2008
- 卷：112
- 期：10
- 页码：2880 - 2887
- 全文大小：232K
- 年卷期：v.112,no.10(March 13, 2008)
- ISSN：1520-5207
文摘
Two-dimensional (2D) correlation analysis based on time-resolved FT-IR/attenuated total reflection (ATR)spectroscopy has been used to study the diffusion behavior of water and mono- or divalent anions in thepositively charged membranes of different charge density. In 2D FT-IR/ATR spectra, the splitting of thewater 
(OH) bending band in the spectral range 1700-1500 cm-1 indicates that there are three differentstates of water in the positively charged membrane, that is, the water molecules forming strong or weakhydrogen bonds with hydrophilic groups of the membrane and water molecularly dispersed with weakerhydrogen bonds. The wavenumber difference of the (OH) band in the low- and high-charge-density membraneindicates that water molecules form much stronger hydrogen bonds with hydrophilic groups in the high-charge-density membrane. The sequential order of the three water bands intensity changes shows that, in theprocess of water diffusion into the high-charge-density membrane, the hydrogen-bonding interaction betweenhydrophilic groups of the membrane and water molecules takes place gradually due to the highly cross-linked network structure of the membrane; in the process of water diffusion into the low-charge-densitymembrane, the strong hydrogen-bonding interaction between hydrophilic groups of the membrane and watermolecules takes place instantaneously and this type of water easily diffuses due to the weak interactionsbetween the water molecules and the membrane polymer. Furthermore, the diffusion processes of the electrolytesolution such as NaAc and Na2SO4 aqueous solutions in the positively charged membrane have also beenexamined.
(OH) bending band in the spectral range 1700-1500 cm-1 indicates that there are three differentstates of water in the positively charged membrane, that is, the water molecules forming strong or weakhydrogen bonds with hydrophilic groups of the membrane and water molecularly dispersed with weakerhydrogen bonds. The wavenumber difference of the (OH) band in the low- and high-charge-density membraneindicates that water molecules form much stronger hydrogen bonds with hydrophilic groups in the high-charge-density membrane. The sequential order of the three water bands intensity changes shows that, in theprocess of water diffusion into the high-charge-density membrane, the hydrogen-bonding interaction betweenhydrophilic groups of the membrane and water molecules takes place gradually due to the highly cross-linked network structure of the membrane; in the process of water diffusion into the low-charge-densitymembrane, the strong hydrogen-bonding interaction between hydrophilic groups of the membrane and watermolecules takes place instantaneously and this type of water easily diffuses due to the weak interactionsbetween the water molecules and the membrane polymer. Furthermore, the diffusion processes of the electrolytesolution such as NaAc and Na2SO4 aqueous solutions in the positively charged membrane have also beenexamined.© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号 地址：北京市海淀区学院路29号 邮编：100083 电话：办公室：(+86 10)66554848；文献借阅、咨询服务、科技查新：66554700 |