ROBINSON, J.P. ... et al, 2004. Solvent flux through dense polymeric nanofiltration membranes. Journal of Membrane Science, 230 (1-2), pp.29-37
This work examines the flux performance of organic solvents through a polydimethylsiloxane
(PDMS) composite membrane. A selection of n-alkanes, i-alkanes and cyclic compounds were
studied in deadend permeation experiments at pressures up to 900 kPa to give fluxes for pure
solvents and mixtures between 10 and 100 l m-2 h-1. Results for the chosen alkanes and
aromatics, and subsequent modelling using the Hagen-Poiseuille equation, suggest that solvent
transport through PDMS can be successfully interpreted via a predominantly hydraulic mechanism.
It is suggested that the mechanism has a greater influence at higher pressures and the modus
operandi is supported by the non-separation of binary solvent mixtures and a dependency on
viscosity and membrane thickness. The effects of swelling that follow solvent-membrane
interactions show that the relative magnitudes of the Hildebrand solubility parameter for the active
membrane layer and the solvent(s) are a good indicator of permeation level. Solvents constituting
a group (e.g. all n-alkanes) induced similar flux behaviours when corrections were made for
viscosity and affected comparable swelling properties in the PDMS membrane layer.