posted on 2009-06-03, 16:20authored bySteve Tarleton, J.P. Robinson, S.J. Smith, J.J.W. Na
The paper describes developmental apparatus for in-situ determinations of membrane swelling and
shows representative examples of the data that can be acquired. The apparatus principally
comprises a linear inductive probe and electronic column gauge with an overall resolution of 0.1
μm which was used in two configurations to assess the swelling propensity of polyacrylonitrile
(PAN)/polydimethylsiloxane (PDMS) nanofiltration membranes in a range of alkane, aromatic and
alcohol solvents.
In the absence of an applied pressure on the membrane, experiments showed a maximum
expansion for the PDMS layer of 169% using an n-heptane solvent whose solubility parameter (δ)
was close to that of PDMS. With more polar solvents falling in the range δ = 23.6-29.2 MPa0.5,
swelling of the PDMS was much reduced (<14%) and comparable shrinkage of the PAN support
layer was also observed. If a mechanical pressure was applied to the membrane then swelling
was reduced. For example with a xylene solvent, over the pressure range 0-10 bar a progressive
decline in membrane swelling from 118% to 50% was observed. At 20 bar swelling was further
reduced to 33%. When xylene or heptane solvent was mixed with methanol, ethanol or propanol,
reduced swelling of the PDMS layer occurred as the concentration of alcohol increased. The
extent of swelling was closely related to the value of the mixture solubility parameter (δmixture) where
a higher value of δmixture led to less swelling. The results of the swelling experiments are compared
to some of the authors previously published results for crossflow nanofiltration and shown to
support the salient features.
Aeronautical, Automotive, Chemical and Materials Engineering
Department
Chemical Engineering
Citation
TARLETON, E.S. ... et al, 2005. New experimental measurements of solvent induced swelling in nanofiltration membranes. Journal of Membrane Science, 261 (1-2), pp.129-135