化工学报 ›› 2007, Vol. 58 ›› Issue (6): 1507-1513.

• 分离工程 • 上一篇    下一篇

单组分电解质溶液中纳滤膜的反射系数

涂丛慧;尚伟娟;王晓琳   

  1. 清华大学化学工程系
  • 出版日期:2007-06-05 发布日期:2007-06-05

Reflection coefficient of nanofiltration membranes in single electrolyte solution

TU Conghui;SHANG Weijuan;WANG Xiaolin   

  • Online:2007-06-05 Published:2007-06-05

摘要: 结合非平衡热力学模型,空间电荷模型(SC)与固定电荷模型(TMS)均可用于预测膜传递系数。反射系数表征膜的最大截流率,是一个重要的膜传递参数。目前,大部分文献对传递参数的研究仅限于1-1型电解质,而对1-2,2-1,2-2型电解质的相关报道则比较少。本文采用数值解法求解SC模型,用解析解法求解TMS模型,计算得到1-1,1-2,2-1,2-2型单组分电解质的反射系数。结果表明,在D2/D1<1.0的情况下,在高浓度区域,σ趋近于0;在低浓度区域,σ趋近于1;在中间浓度区域,随着电解质浓度的升高,σ单调减小。而在D2/D1>1的情况下,中间浓度区域σ出现负的最小值。此外,随着膜孔表面电荷密度的升高或者膜孔半径的减小,σ增大。最后,本文将SC模型与TMS模型的结果进行了比较,得到,当q0 <1.0 且 rp <5.0nm的条件下,两个模型有很好的一致性。

关键词:

反射系数, 空间电荷模型, 固定电荷模型, 纳滤膜

Abstract:

The space-charge(SC)model and Teorell-Meyer-Sievers(TMS)model combined with irreversible thermodynamics model are applied to predict the transport coefficients of nanofiltration membranes in single electrolyte solution.The reflection coefficient has been numerically calculated by the SC model and analytically calculated by TMS model.The results show that the reflection coefficient approaches unit in the range of low-concentration regime and approaches zero in the range of high-concentration.While the diffusion coefficients ratio of co-ion over counterion is less than 1.0;the reflection coefficient is positive over the whole concentration range.When the ratio is larger than 1.0;the reflection coefficient is negative in a certain intermediate concentration region.And the increase of the surface charge density and the decrease of the pore radius cause the increase in the reflection coefficient.The SC model and TMS model show good agreement in the calculation of the reflection coefficient when the dimensionless potential gradient in the pore surfaces is less than 1.0 and the pore radius is less than 5.0 nm.

Key words:

反射系数, 空间电荷模型, 固定电荷模型, 纳滤膜