Synthesis of zirconia monoliths for chromatographic separations.
The aim of this work is to join the advantages of two different kinds of stationary phases: monolithic columns and zirconia-based supports. On the one hand, silica monolithic columns allow a higher efficiency with a lower back-pressure than traditional packed columns. On the other hand, chromatographic stationary phases based on zirconia have a higher thermal and chemical stability and specific surface properties. Combining these advantages, a zirconia monolith with a macroporous framework could be a real improvement in separation sciences. Two main strategies can be used in order to obtain a zirconia surface on a monolithic skeleton: coating or direct synthesis. The coverage by a zirconia layer of the surface of a silica-based monolith can be performed using the chemical properties of the silanol surface groups. We realized this coverage using zirconium alkoxide and we further grafted n-dodecyl groups using phosphate derivatives. Any loss of efficiency was observed and fast separations have been achieved. The main advance reported in this paper is related to the preparation of zirconia monoliths by a sol-gel process starting from zirconium alkoxide. The synthesis parameters (hydrolysis ratio, porogen type, precursor concentration, drying step, etc.) were defined in order to produce a macroporous zirconia monoliths usable in separation techniques. We produced various homogeneous structures: zirconia rod 2 cm long with a diameter of 2.3 mm, and zirconia monolith inside fused silica capillaries with a 75 microm I.D. These monoliths have a skeleton size of 2 microm and have an average through pore size of 6 microm. Several separations have been reported.
Randon
Jérôme
J
Laboratoire des Sciences Analytiques, UCBL - Bat 308, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne Cedex, France. randon@univ-lyon.fr
Huguet
Samuel
S
Piram
Anne
A
Puy
Guillaume
G
Demesmay
Claire
C
Rocca
Jean-Louis
JL
D000588:Amines / Q000302:isolation & purification; D001555:Benzene Derivatives / Q000302:isolation & purification; D002853:Chromatography, Liquid / Q000295:instrumentation* / Q000379:methods; D008855:Microscopy, Electron, Scanning; D012822:Silicon Dioxide; D013499:Surface Properties; D015040:Zirconium / Q000737:chemistry*
D000588:Amines; D001555:Benzene Derivatives; D012822:Silicon Dioxide; D015040:Zirconium; C028541:zirconium oxide