Non-aqueous nanofiltration: solute rejection in low-polarity binary systems

Solvent type influenced membrane swelling to an extent dependent on the relative magnitude of the solubility parameters for the solvent and PDMS; similar values led to more swelling, higher fluxes and lower rejections. Results support the concept of viscous solvent flow whilst solute transport could be either predominantly viscous or a combination of viscous and diffusive. With larger molecules, a size exclusion mechanism was dominant. A new model is proposed that takes account of solute transport by a combination of viscous and diffusive mechanisms and this is shown to well represent the experimental data.