Porosity

Abstract

This article details the most important techniques used to characterize membrane porosity and pore size distribution. A variety of methods that provide direct and indirect information about the pores' structure, distribution, and morphology are overviewed, including microscopy‐based techniques, solute retention test and modeling, dusty gas model, picnometry, permporometry, thermoporometry, gas adsorption‐desorption, and displacement porosimetry.

An AFM study of ultrafiltration membranes: Peculiarities of pore size distribution

“…In conclusion, it should be noted that the revealed bimodality of pore size distribution of an ultrafiltration membrane has already been reported by Calvo et al [11], who also detected the second maximum in the pore size distribution. However, the physical explana tion of this phenomenon is still missing.…”

Fitting approach to liquid–liquid displacement porosimetry based on the log-normal pore size distribution

“…Both techniques have been indistinctly named as capillary flow porometry, [1], liquid extrusion porometry, [2], or even combined bubble pressure and solvent permeability method, [3,4], but all of them refer to the same principle, [5].…”

Porosimetric characterization of polysulfone ultrafiltration membranes by image analysis and liquid–liquid displacement technique

“…However in the case of GR61PP this procedure did not lead to good results since the behavior of the flux vs. applied pressure appeared very peculiar and different from that found for the GR70PE membrane which presented a S-shape curve typical of displacing porosimetry, [11]. So, taking profit of the feature that both liquids can interchange their roles, a new series of measurements were done by using now the alcohol rich phase as wetting liquid.…”

“…Techniques, such as those based on the bubble point test that have gained enormous relevance for the characterization of microfiltration membranes, cannot be properly applied to UF membranes due to the high pressure (more than 10 bar) to be applied in order to evaluate pore sizes below 0.1 µm, owing to the high value of the surface tension ( = 72 mN/m) between air and the wetting liquid (water), [11]. On the contrary Liquid-Liquid Displacement Porosimetry (LLDP), because it uses a pair of immiscible liquids with very low interfacial tension is very suitable for characterizing UF membranes at relatively low applied pressures.…”

“…Many characterization methods like permporometry, thermoporometry, mercury porosimetry, gas adsorption-desorption, nuclear magnetic resonance, gas-liquid and liquid-liquid porosimetry along with several microscopic techniques, both electronic as scanning and transmission electron microscopy and atomic as atomic force microscopy, have been used to analyze the pore structure and pore size distribution of the membrane, [11]. Each of these methods has different features, principles of operation and need different theoretical considerations to convert the direct results into pore sizes.…”