Phase separation of polyethylene glycol/salt aqueous two-phase systems

Chan Wha Kim, Chokyun Rha

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8 Citations (Scopus)


Salt in polyethylene glycol (PEG)/salt aqueous two-phase systems was excluded by PEG and concentrated in the solvent volume available for dissolution of salt (PEG-free solvent). The concentration of salt in the PEG-free solvent of the PEG-rich phase was the same as that at the critical point regardless of the compositions of the PEG/salt two-phase systems. This explained that the phase separation of PEG/salt two-phase systems occurs when the concentration of salt in the PEG-free solvent reaches its solubility limit. The concentration of salt required in the PEG-free solvent for the phase separation was lower with higher molecular weight of PEG. The solubility of salt in the PEG-free solvent decreased with increases in the molal surface tension increment of salt. The solubility limit of salt in the PEG-free solvent was 0.93 M for ammonium sulfate, 0.77 M for potassium phosphate, 0.75 M for sodium tartrate, 0.67 M for sodium phosphate, and 0.53 M for potassium citrate.

Original languageEnglish
Pages (from-to)181-191
Number of pages11
JournalPhysics and Chemistry of Liquids
Issue number2
Publication statusPublished - 2000 Jan 1



  • Aqueous two-phase system
  • Excluded volume
  • PEG
  • Phase separation
  • Solubility of salt

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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