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Chem. J. Chinese Universities ›› 2010, Vol. 31 ›› Issue (4): 782.

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Application of the Electrostatic and Steric-hindrance Model to Analysis of Transmembrane Potential Across Nanofiltration Membranes

FANG Yan-Yan, TU Cong-Hui, WANG Xiao-Lin*   

  1. Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
  • Received:2009-06-25 Online:2010-04-10 Published:2010-04-10
  • Contact: WANG Xiao-Lin. E-mail: xl-wang@tsinghua.edu.cn
  • Supported by:

    国家“九七三”计划项目(批准号: 2009CB623404)和国家“八六三”计划项目(批准号: 2009AA062901)资助.

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Abstract:

The electrostatic and steric-hindrance model was employed to analysis transmembrane potential arising across nanofiltration membranes theoretically. The effects of solution volume flux, feed concentration, diffusion coefficient ratio of co-ion to counterion, membrane pore radius and membrane volume charge density on transmembran potential including membrane potential and convective potential across nanofiltration membranes in KCl(1-1 electrolyte) and MgCl2(2-1 electrolyte) were investigated. The results showed that the linearity of transmembrane potential of KCl and MgCl2 increased with increase of solution volume flux. Transmembrane potential of the two electrolytes decreased while feed concentration and pore radius increased. Due to the complex mechanism, the influence of diffusion coefficient ratio of co-ion to counterion on potentials behaved differently in different concentration range and electrolyte species. Compared with MgCl2, the curves of transmembrane potential of KCl as a function of membrane volume charge density exhibited evidently symmetry on the origin, but transmembrane potential zero point of MgCl2 appeared when membrane volume charge density was negative.

Key words: Transmemebrane potential; Electrostatic and steric-hindrance model; Nanofiltration membrane

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