Zirconia–zircon composite microfiltration membranes based on porous alumina supports

Supported zirconia–zircon composite microfiltration layers produced by the dip-coating procedure are introduced for the first time. These can be produced using commercial grade monoclinic-zirconia powders having high silica content. Such membranes have the advantage of enhanced sintering due to a liquid-phase mechanism. These were prepared through dip-coating α-alumina supports with slips of zirconia powder stabilized with ‘aluminon’ and further sintering (1050–1200 °C). Optimum dispersant concentration and pH had been found based on sedimentation tests and UV–vis spectroscopy method. The effect of slip concentration, sintering temperature and number of coatings on the membrane characteristics has been studied. There exists a maximum sintering temperature of 1150 °C for the creation of minimum pore diameters lower than 0.2 μm with a reasonable surface microhardness of Hardness Vickers at 50 g force pyramidal load (ca. 110 HV50) and no observable crack. This work includes a comparative study with membrane layers produced with an analogous preparatory method using high purity monoclinic zirconia with a similar particle size distribution.