MICROFILTRATION THROUGH AN INFILTRATED AND A NONINFILTRATED INORGANICCOMPOSITE MEMBRANE

The experimental hydraulic resistance of a composite inorganic membran e can be much larger than the resistance obtained by summing all the l ayers resistances. This is explained by a transition boundary layer be tween two porous media of drastically different sizes. A new route of membrane synthesis is then proposed to minimize this effect. Noninfilt rated titania membranes of 0.2, 0.5 and 0.8 mu m mean pore diameter ar e compared to classical infiltrated membranes made with the same mater ial under the same mechanical conditions. The noninfiltrated membranes have increased permeabilities of 30 to 70%. They are less sensitive t o fouling by a suspension of ferric hydroxide particles and the limiti ng fluxes are considerably increased.