Basic Principles of Membrane Synthesis

In this section a short introduction will be given on the synthesis of porous ceramic membranes by sol-gel techniques and anodization, carbon membranes, glass membranes and track-etch membranes. An extensive discussion will be given in Sections 2.3-2.S. 

Terms such as symmetric and asymmetric, as well as microporous, meso-porous and macroporous materials will be introduced. Symmetric membranes are systems with a homogeneous structure throughout the membrane. Examples can be found in capillary glass membranes or anodized alumina membranes. Asymmetric membranes have a gradual change in structure throughout the membrane. In most cases these are composite membranes 

Pore diameters larger than 50 nm are called macropores, mesopores have a diameter between 2 and 50 nm and below a diameter of 2 nm the system is called microporous (Sing et al. 1985). 

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