CHEMICALLY-DURABLE SILICA-ZIRCONIA NANOFILTRATION MEMBRANES

MICROPOROUS SILICA-ZIRCONIA MEMBRANES THAT EXHIBIT EFFICIENTSEPARATION FOR LOW MOLECULAR WEIGHT (<1,000 G/MOL) COMPOUNDSARE BEING DEVELOPED. SUCH MEMBRANES SHOULD DISPLAY SEPARATION CAPABILITIES COMPARABLE TO ANALOGOUS MEMBRANES COMPOSED OF PURE SILICA AND WILL HAVE GREATLY ENHANCED CHEMICAL DURABILITY COMPARED TO THE PURE SILICA MEMBRANES. PREPARATION OF THESE MEMBRANES IS CONTROLLABLE IN ORDER TO ATTAIN NARROW PORE SIZE DISTRIBUTIONS WITH CHARACTERISTIC PORE DIAMETERS RANGING FROM 5 TO 10 ANGSTROMS. SUCH MEMBRANES ARE SUITABLE FOR NANOFILTRATION APPLICATIONS INVOLVING ELEVATED TEMPERATURES AND/OR AGGRESSIVE CHEMICAL ENVIRONMENTS. THE TECHNICAL APPROACH FOR FABRICATION FOR THESE MEMBRANES USES A PROCEDURE FOR PREPARING PURE MICROPOROUS SILICA MEMBRANES AS A STARTING POINT. INCORPORATION OF ZIRCONIA INTO THE MICROPOROUS MEMBRANES BY SEVERAL DIFFERENT METHODS IS BEING INVESTIGATED. IN PHASE I, 5 CM(2) ALUMINA ULTRAFILTRATION DISKS WITH SINTERED INTERMEDIATE LAYERS COMPOSED OF ALUMINA WITH 2 TO 5 NM PORE SIZE ARE BEING USED AS SUPPORTS FOR THE COMPOSITE MEMBRANE LAYERS. THE DISK-SUPPORTED MEMBRANES WILL BE TESTED IN STIRRED ULTRAFILTRATION CELLS TO MEASURE LIQUID PERMEABILITIES AND RETENTION CHARACTERISTICS. SAMPLES EXHIBITING PROMISING SEPARATION CHARACTERISTICS WILL ALSO BESUBJECTED TO CHEMICAL DURABILITY TESTING INVOLVING EXPOSURE TO WATER VAPOR AND ALKALI SPECIES AT BOTH AMBIENT AND ELEVATED TEMPERATURES.