Porous Ceramic Supports for Membranes Prepared from Kaolin (DD3) and Calcite Mixtures

The supports for microfiltration (MF) and ultrafiltration (UF) were prepared with local kaolin (Djebel Debagh: type 3: DD3) and calcium carbonate (CaCO₃) mixtures. The choice of these materials is based on their natural abundance (low price). In this work, the tubular ceramic supports were prepared by the extrusion method. The sintering was carried out for 2 hours, at temperatures laying between 1150 and 1300°C. They are then characterized by various techniques: mercury porosimetry, scanning electron microscopy and x-ray diffraction. The obtained results revealed that the main phase formed during the sintering step was anorthite with a minor phase of mullite. Moreover, it has been found that supports sintered at temperatures less than 1300°C had interesting characteristics; an average pore size ranged between 3.91-8.56 μm, a porosity ratio of 42.0-50.4%, a flexural strength ≈67-77 MPa and the pore size distribution is bimodal type. According to their average pore sizes, they may be used either as supports for MF or UF membranes