Transactions of the INDIAN CERAMIC SOCIETY Vol. 63 2004
Electrochemical and Electrokinetic Aspects of
Ceramic Nanofiltration Membranes
P. Árki and G. Tomandl
Pages : 99-104
DOI :10.1080/0371750X.2004.11012141
Abstract
Membrane separation in the nanofiltration range does not only result from a pure sieving effect of the pore structure, but is also strongly influenced by the surface charge properties of the membrane surface and the surface of the pore walls. In the case of liquid saturated oxide ceramic membranes, a surface charge results from dissociated surface groups and adsorbed ions. The aim of the present research therefore is the electrochemical and electrokinetic determination of the charges of ceramic nano-filtration membranes under varying electrochemical conditions and the influences of these effects on the filtration properties. Oxide ceramic nanofiltration membranes of TiO2 were characterized. Direct methods for determining the membrane charges use electrokinetic effects like streaming potential (tangential and perpendicular method). Indirect methods use measurements of the electromotive force and the salt rejection during permeation measurements. The investigations show the possibility for adjusting the separation characteristic up to a nearly complete salt rejection by choosing the appropriate pH-value, concentration and the kind of the salt solution. Using magnitude and sign of the streaming potential the separation properties with salt solutions can be predicted. This could be checked by cross-flow filtration experiments.
