HAFNIA CERAMIC NANOFILTRATION MEMBRANES - PART I - PREPARATION AND CHARACTERIZATION

We have used a sol-gel process as an efficient method for the preparat ion of hafnia nanofiltration membranes. A stable colloidal sol was obt ained after hydrolysis of an alkoxide and peptization of the hydrous o xide precipitate. After the drying of the sol, the hafnia powder was c haracterized using several methods, such as X-ray diffraction, dilatom etry, thermal analysis, electrophoretic, and BET measurements. The haf nia membrane was obtained by coating the colloidal sol on a mesoporous ceramic support, followed by a drying and sintering of the gelled lay er. The membrane was characterized by SEM and nitrogen adsorption-deso rption to determine the pore size. The filtration properties of a hafn ia membrane sintered at 450 degrees C were determined using water perm eability and rejection of solutions containing sucrose, polyethylene g lycols of different molecular weights (400, 600, 1000) and salt soluti ons. This membrane is characterized by a MWCO of 420 Da and pore size near 1 nm. (C) 1998 Elsevier Science B.V. All rights reserved.