Comparison of extruded and pressed low cost ceramic supports for microfiltration membranes

A comparison has been made between ceramic supports for microfiltration membranes of the same composition obtained by pressing and by extrusion in terms of microstructure and properties.The extruded supports displayed lower porosity and smaller pore size than pressed supports. 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 supports 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.