Synthesis and characterization of microporous zirconia powders: Application in nanofilters and nanofiltration characteristics

Mineral nanofiltration membranes are not commercially available because it is difficult to generate connected micropores in an inorganic material. Recent advances in sol-gel chemistry can be applied for the preparation of mineral oxide particles allowing the formation of a microporous structure after sintering. Zirconia has been chosen as a membrane material because of its chemical and thermal stabilities. Initially powders were synthesized and characterized to determine the optimal synthesis conditions for application in the preparation of membranes. Magnesium oxide stabilized zirconia (13 mol.%) demonstrated high surface areas leading to elevated surface charge densities. Crack-free coating could be deposited on ceramic multichannel substrates. The development of these membranes has permitted both model solute rejections in the 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-channel configuration. The high surface charge density of the membrane material ensured a large divalent anion rejection (66.3% sulfates) and a low rejection of monovalent anions (31.5% chlorides).