Characterization of clean and fouled ultrafiltration membranes

Abstract

Much research into the fundamentals of membrane formation and separation has been performed in order to improve the efficiency of the manufacture of ultrafiltration membranes. Determination of the membrane characteristics is a key problem in these investigations. In this paper, we report on a study of membrane morphology by fractional rejection measurements, using low molecular weight saccharides as the test solute, and by electron microscopy. Using a simple model for solute/solvent transport through cylindrical pores, a "characteristic pore size" was derived from saccharide rejection data. This pore size of a hypothetical isoporous membrane, interpreting the measured separation characteristics, provides a promising means of describing differences between membranes with respect to pore size and pore size changes caused by solute adsorption. From high resolution electron micrographs, information was obtained on the skin layer morphologies and, for some membranes the sizes of the larger pores could be estimated.

The effect of polymer concentration on flux stability of polysulfone membrane

“…It has been known that fouling on a membrane surface alters the separation characteristic of the membrane [38,39]. Low cross flow velocity and transmembrane pressure lead to higher concentration of the rejected solute on the membrane surface, due to the longer time of membrane exposure to the raw water.…”

Comparative study of red grape must nanofiltration: Laboratory and pilot plant scales

“…The additional resistance attributed to fouling, R f , has been related with phenomena such as concentration polarization, gelation, deposition, adsorption of solute molecules inside the pores or pore blocking when the pore size is similar to the molecular dimensions (Bowen et al, 1995;Chudacek and Fane, 1984;Hanemaaijer et al, 1988;Seman et al, 2010;Zeman, 1983). All these processes should influence in a more or less balanced equilibrium.…”

Electron microscopy in synthetic polymer membrane research

“…Surface porosity and pore size. Pore size, size distribution and porosity can be estimated by a number of different techniques such as MWCO determination (Kesting, 1971;Jonsson, 1985;Tragard, 1985;Smolders & Vugteveen, 1985;Cheryan, 1986;Hanemaaijer et al, 1988), bubble point/solvent permeability (Kamide & Manabe, 1980;Capannelli et al, 1983;Munari er al., 1985;Zeni et al, 1988) and thermoporometry (Brun et al, 1977;Smolders & Vugteveen, 1985;Zeman et al, 1987;Quinson & Brun, 1988). However, most techniques rely upon analysis of indirect data.…”