Molecular weight cut-off determination of organic solvent nanofiltration membranes using poly(propylene glycol)

Christopher Davey, Ze Xian Low, Remigius Wirawan, Darrell Patterson

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A new method for determining the molecular weight cut-off (MWCO) of an organic solvent nanofiltration (OSN) membrane has been developed utilising poly(propylene) glycol (PPG) oligomers. This new MWCO method overcomes the limitations of the currently popular methods: namely the high molecule cost in the popular polystyrene method, the Donnan Exclusion effects when using dye molecules and the solvent compatibility and HPLC separation resolution limitations of the lesser used poly(ethylene) glycol (PEG) method. A new reverse phase high-performance liquid chromatography separation with evaporative light scattering detection (ELSD) allows the concentration of each oligomer of PPG to be accurately determined and from this the MWCO curves are constructed. The method has a high resolution (size increment of 58 g mol-1 corresponding to the OCH(CH3)CH2 structural unit) and can be used in polar, polar aprotic, and non-polar solvents. The accuracy of the method has been demonstrated in three different solvents (methanol, acetone, and toluene) and 5 different OSN membranes (DuraMem® 150, 200, 500, PuraMem® 280 and StarMemTM 240). Other advantages include; oligomers of PPG are cheap and widely available, can probe a wide range of MWCO and provide high resolution MWCO curves. Consequently, it is proposed that that this method be adopted as a new standard MWCO test for OSN membranes.
Original languageEnglish
Pages (from-to)221-228
Number of pages8
JournalJournal of Membrane Science
Early online date21 Dec 2016
Publication statusPublished - 15 Mar 2017


  • Molecular weight cut-off (MWCO)
  • organic solvent nanofiltration (OSN)
  • ); Solvent Resistant Nanofiltration (SRNF)
  • Poly(propylene) glycol (PPG)
  • Poly(propylene) oxide (PPO)
  • ); reverse phase high-performance liquid chromatography (HPLC)
  • evaporative light scattering detection (ELSD)
  • Membranes

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Filtration and Separation
  • Analytical Chemistry
  • Fluid Flow and Transfer Processes


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