EXTRUDED AND PRESSED CERAMIC MICROFILTRATION MEMBRANES

Abstract
A comparison has been made between ceramic microfiltration membranes of the same
composition obtained by pressing and by extrusion in terms of microstructure and
properties.
The extruded membranes displayed lower porosity and smaller pore size than pressed
membranes. The higher the clay content in the starting composition, the clearer this
tendency became. In contrast, the difference tended to disappear when starch was
added to the initial composition. The mechanical strength values followed a decreasing
exponential variation with porosity, which was influenced by the starting composition
and the shaping method.
Water permeability reflected the strong effect of the mean pore size. The membranes
synthesised from the composition with the higher clay content showed the lowest
permeability, while those obtained from the composition including starch showed the
highest value. A model derived from the Hagen-Poiseuille equation enabled the
tortuosity values to be calculated.