Evaluation of the ideal selectivity and the performance of selectrodialysis by using TFC ion exchange membranes

Wenguang Wang, Ru Liu, Ming Tan, Haixiang Sun, Q. Jason Niu, Tongwen Xu, Victor Nikonenko, Yang Zhang

Research output: Contribution to journalArticlepeer-review

51 Scopus citations

Abstract

The current methods for determination of the membrane specific permselectivity between two competing counter-ions are dependent on various factors, which hinder the comparison of ion selectivity of ion selective membranes. In this work, a new characteristic, “ideal selectivity” is suggested to be used for the evaluation of the specific permselectivity of monovalent selective membranes. Ideal selectivity is determined in a single electrolyte solution containing only one of the competing counterions. We show that this characteristic exhibits a stable value, which is independent from the molar fraction of ions in a solution. Thus, it may be directly used to predict the purity of a salt produced in a dynamic selectrodialysis (SED) process with a monovalent selective membrane. To elaborate this, thin film composite (TFC) cation exchange membranes were prepared with piperazine and trimesoyl chloride by interfacial polymerization. These membranes were compared with a commercial monovalent selective cation exchange membrane CIMS (ASTOM, Japan) in view of their permselectivity (Na+/Mg2+) and the performance in SED. The results show that when the TFC membranes were applied in SED, the purity of Mg2+ in the product reached 75%, which was higher than in the case of CIMS. Furthermore, ideal selectivity of those TFC and CIMS membranes were calculated and fitted with the experimental Mg2+ purity. It was found that ideal selectivity linearly correlates with the product final purity. The extrapolation of the fitting line predicts that when ideal selectivity approaches to 2, SED process the purity could theoretically approach to 100% in the same experimental conditions. Therefore, ideal selectivity can be used to predict the separation efficiency and the final product purity of SED process.

Original languageEnglish
Pages (from-to)236-245
Number of pages10
JournalJournal of Membrane Science
Volume582
DOIs
StatePublished - 15 Jul 2019
Externally publishedYes

Keywords

  • Ideal selectivity
  • Monovalent selective membrane
  • Product purity
  • Selectrodialysis
  • TFC ion exchange membrane

ASJC Scopus subject areas

  • Biochemistry
  • General Materials Science
  • Physical and Theoretical Chemistry
  • Filtration and Separation

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