Preparation and characterization of tubular ceramic membranes for treatment of oil emulsions

Multilayer membranes for the treatment of oily waters have been prepared from ceramic materials. Alumina and cordierite supports have been prepared as well as α-Al2O3 intermediate layers. γ-Al2O3 top layers with very high porosities were prepared by the sol-gel method and a detailed study has been performed because of the importance of this layer in the filtration process. A structural study by means of nitrogen adsorption-desorption, nitrogen permeability and scanning electron microscopy has been carried out on unsupported and supported top layers membranes. The effect of the sol concentration and calcination temperature on the structure of the membrane was studied to get an appropriate pore size and porosity. Also, the necessary amount of PVA as binder/plastizier to get defect-free membranes was investigated. Top-layer membranes in tubular configuration with an average pore diameter around 4 nm and porosities of 72% have been obtained.