Colloidal Processing of Powder for Membrane Applications
Consolidation of colloidal particles onto porous ceramic substrate is the critical issue in the ceramic membrane preparation. The membrane functional properties are determined mainly by the powder properties, but also by the colloidal condition of the slip. This presentation concentrates on the colloidal processing of submicron alumina for the membrane preparation and for the membrane layer formation based on the capillary colloidal filtration. The solid content of the slip and the degree of deflocculation are the primary factors for the control of the membrane layer growth and pore properties. Electrostatic and electrosteric dispersion lead into different degree of deflocculation and different surface charge, which further resulted on differences in membrane layer growth behavior. Additives, such as polyelectrolytes, electrolytes, binders have also effect on the colloidal condition of the slip, but also have effect on the properties of the liquid phase of the slip. Changes in viscosity and surface tension of liquid phase have also significant effect on the membrane layer growth behavior.
R.E. Levänen "Colloidal Processing of Powder for Membrane Applications", Advances in Science and Technology, Vol. 45, pp. 382-390, 2006