The preparation and characterization of alumina-coated pyrophyllite-diatomite composite support layers

Porous ceramic membranes are a current research focus because of their outstanding thermal and chemical stabilities. Recent research has utilized inexpensive natural materials such as pyrophyllite and diatomite to reduce the expense of these porous ceramic membranes. However, insufficient data exist for microfiltration applications using pyrophyllite-based membranes. We compared the measured membrane properties of alumina-coated alumina support layers and alumina-coated pyrophyllite-diatomite composite support layers. These experiments were used to determine whether we could effectively reduce the average pore size with acceptable water permeability by controlling the thickness of the alumina coating layer. The membrane properties of the alumina-coated alumina support layers and alumina-coated pyrophyllite-diatomite composite support layers were examined using scanning electron microscopy, mercury porosimetry, and a dead-end microfiltration system.