Separation of Aqueous Ionized Molecule-Salt Solutions

3 Separation of Aqueous Ionized Molecule-Salt Solutions 

Schirg and Widmer [52] published mathematical models for the calculation of retention and selectivity for nanofiltration of aqueous dye-salt solutions. A modification of Eqs. (12.11) and (12.12) has been proposed in which the integral salt permeability co could be described by the introduction of an exponential function 

Both calculations by Perry and Schirg have been performed to describe and to predict the rejection characteristics of organic nanofiltration membranes when ionic and charged molecular solute mixtures are used in the feed solution. Recently experiments were carried out with ceramic nanofilters [67] which showed that similar properties can be obtained. As an example, results concerning the rejection of a dye/electrolyte mixture at pH = 9 through a zirconia nanofilter are reported in Table 12.5. 

As a general conclusion to this part dedicated to nanofiltration with ceramic membranes one can assume that the general behaviour of these membranes can be assimilated to the behaviour of electrically charged organic nanofiltration membranes. However some specificities exist with ceramic nanofilters due to a sintered metal oxide grains derived porous structure and an amphoteric character 

Rejection of a mixture of an organic anion (bromocresol green) and salt anions (SOI, Cl ) through a negatively charged zirconia nanofilter [67] 

---