Effect of solvent properties on permeate flow through nanofiltration membranes. Part I: investigation of parameters affecting solvent flux

The objective of the present study was to characterize transport properties of solvents permeating through solvent resistant nanofiltration membranes that have only recently become available. Permeation flows of a number of solvents of different chemical families were measured in a batch cell. The solvents studied were alcohols, paraffins, ketones, acetates, and water, as well as their binary mixtures. The experimental data revealed a marked variation in the level of permeate flux among the various solvents. For instance, permeation flow of pentane was about 60-times faster compared to that of water while permeation flow of ethanol was about 10-times faster than that of water. The dependence of solution flux on the fractional composition of the solvents in the mixture was found to be highly non-linear. The flux of either pure or mixed solvents was mainly affected by surface tension and viscosity of the solvents. The flux of paraffins mixtures in particular was affected by the dielectric constant also. (C) 1999 Elsevier Science B.V. All rights reserved.