STUDY OF ELECTROKINETIC PROPERTIES OF PLATE CERAMIC MEMBRANES BY ELECTROOSMOSIS AND STREAMING POTENTIAL

Two electrokinetic techniques, electro-osmosis and streaming potential , have been used to investigate the charge characteristics of mixed al umina/titania/silica microfiltration membranes. Both methods can be ap plied to the membrane itself and streaming potential can be measured d uring the filtration process, Electroosmosis and streaming potential g ive very close results in term of isoelectric points, whatever the ele ctrolyte is. The low isoelectric point value suggests that the silica contained in membranes is mainly concentrate at the surface. Both tech niques show the modification of the electrokinetic surface properties due to the specific adsorption of sulphate ions onto the membranes sur face, The greater zeta potential values determined from electroosmotic flow rate measurements suggest that the shearing plane is nearer the solid surface during electroosmosis. This assumption is strengthened b y the increase of the ratio between the zeta potentials determined fro m both techniques as ionic strength increases.