Citation: ROBINSON, J.P. ... et al, 2004. Solvent flux through dense polymeric nanofiltration membranes.Journal of Membrane Science, 230 (1-2), pp. [29][30][31][32][33][34][35][36][37] Additional Information:• ABSTRACTThis 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.

Citation: WAKEMAN, R.J., SABRI, M.N. and TARLETON, E.S., 1991. Factors affecting the formation and properties of wet compacts. Powder Technology, 65, Additional Information:• ABSTRACTNew data are reported on the formation of wet compacts from slurries. The compaction data are analysed through two consecutive mechanisms, filtration and consolidation. Process design parameters for each mechanism are obtained from the models which might allow calculations to be made from small-scale experiments. The magnitude and dependence of the constitutive parameters on pressure, pH and surface charge, particle size and shape, and the nature of the particle-particle interactions are shown through the experimental results.

This paper describes improvements to an apparatus for in-situ determinations of swelling where a linear inductive probe and electronic column gauge with an overall resolution of 0.1 µm was used for measurements of seven variants of polyacrylonitrile (PAN)/polydimethylsiloxane (PDMS) composite nanofiltration membranes in a range of alkane, aromatic and alcohol solvents. The unswollen membranes incorporated PDMS layers between 1 and 10 μm nominal thickness and were manufactured with a radiation and/or thermal crosslinking step.The tested membranes exhibited a range of swelling dependent on the degree of crosslinking, the initial PDMS layer thickness and the type of solvent. With no applied pressure the PDMS layer on some radiation crosslinked membranes swelled as much as ~170% of the initial thickness whilst other membranes were restricted to a maximum swelling of ~80%. When a pressure up to 2000 kPa was applied to a membrane then swelling could be reduced to ~20% of the value obtained at zero applied pressure. By vertically stacking up to 3 membrane samples it was possible to determine the swelling of PDMS layers as thin as 1 μm, although higher imposed pressures rendered some results unreliable as the measurement resolution of the apparatus was approached. The results of the swelling experiments are contrasted with crossflow nanofiltration performance in terms of solvent flux and solute rejection.

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