SYNTHESIS AND CHARACTERIZATION OF MICROPOROUS ZIRCONIA POWDERS - APPLICATION IN NANOFILTERS AND NANOFILTRATION CHARACTERISTICS

Mineral nanofiltration membranes are not commercially available becaus e it is difficult to generate connected micropores in an inorganic mat erial. Recent advances in sol-gel chemistry can be applied for the pre paration of mineral oxide particles allowing the formation of a microp orous structure after sintering. Zirconia has been chosen as a membran e material because of its chemical and thermal stabilities. Initially powders were synthesized and characterized to determine the optimal sy nthesis conditions for application in the preparation of membranes. Ma gnesium oxide stabilized zirconia (13 mol.%) demonstrated high surface areas leading to elevated surface charge densities. Crack-free coatin g could be deposited on ceramic multichannel substrates. The developme nt of these membranes has permitted both model solute rejections in th e nanofiltration range (73.2% B-12 vitamin and 54.5% saccharose), high water permeability (12.31/h m(2) bar) and high fluxes with a 19-chann el configuration. The high surface charge density of the membrane mate rial ensured a large divalent anion rejection (66.3% sulfates) and a l ow rejection of monovalent anions (31.5% chlorides).