Synthesis of inorganic membrane by sol–gel process

Abstract

There has been a growing interest in the use of inorganic membrane for several industrial and laboratory applications. This is because they offer many advantages over organic counterparts in separation processes. These include resistance to compaction under high pressure, chemical stability at high temperature (including steam sterilisation procedures), insensitivity to bacterial action and a long operational life. In the field of water and waste-water treatment, micro and ultrafiltration through an inorganic membrane are most promising technologies. Among the methods of preparation developed, the sol–gel process is appropriate to elaborate thin and porous layers with controllable porosity on a wide range of chemically resistant macroporous substrates. The synthesis of gel is based on hydrolysis–condensation reactions indirectly to form a veritable lattice of oxide from molecular precursors. The whole chemical reactions and experimental conditions (concentration, temperature, nature of precursors) influence strongly structural, morphologic characteristics of solid phase. Solution chemistry is which weak interactions favor the self assembly of molecular precursors opens many possibilities for the synthesis of oxide materials. The control of sol–gel transition and thermal decomposition has allowed us the synthesis of ZrO 2 oxide. The deposit thin layers has been realized with a sol prepared with the destabilization of colloïdal solutions process. This is possible by infiltrating a low viscosity sol or by direct coating on to an ultrafiltration. We have chosen to study ZrO 2 oxide for their interesting properties and the interest which may bring in the domain of inorganic membranes chemical and mechanical high resistance. The structural characterisation was studied by differential thermal analysis, infrared spectroscopy, X-ray diffraction. The textural characterisation by nitrogen adsorption–desorption allowed us to observe the variation of the surface area, porous volume and pore diameters according to temperature. Scanning electron-spectroscopy observation showed homogeneous layers without cracking. The sol–gel process is particularly well suited at the realization of thin microporous layers. In this paper, some experimental results on the synthesis and characterization of inorganic membrane will be presented.