Elsevier Science Publishers

The tubular ceramic membrane system prepared by us consists of a substrate which is made by means of extrusion, and a microfiltration layer which is about 30 pm thick and which is applied by a film coating technique. This two layer system can also be used as a substrate for an ultrafiltration or gas separation membrane layer which is then also applied by a coating technique. The water fluxes for different substrate-MF layer combinations are given and the influence of the substrate permeability on the total permeability is discussed. It is also shown by the permeability of some gases that the three layer system can be used for gas separation.

Substrate tubes with different properties were fabricated and were used to support microfiltration layers with different properties. The influence of the resistance of the substrate tube on the permeability of the system is calculated. These results can be used to choose the optimum MF layer-substrate combination taking into account that in general the strength of the substrate decreases with increasing permeability. It is also shown that the substrate-MF system can be used as a carrier system for an ultrafiltration or gas separation membrane. The separation or enrichment in case of a gas mixture occurs due to a difference in Knudsen diffusion which means that the larger the difference in molecular masses of the components of the mixture the higher the separation factor will be. The performance of the membrane system will be tested extensively in the near future. Only preliminary tests have been carried out so far.