New clay–alumina porous capillary supports for filtration application

Ceramic pastes of different clay–alumina compositions were prepared with required rheological property for extrusion processing. The composition was varied from 0 to 85 weight percent (wt.%) of clay and remaining alumina and mixed with different organic additives which acted as binder, plasticizer, pore former along with water. The paste was then extruded to green capillary tubes with dimensions of 3.5/2.0 mm (OD/ID) through a specifically designed extrusion die. The green capillary tubes were dried at room temperature for 24 h and sintered at three different temperatures of 1200 °C, 1300 °C and 1450 °C, before their characterization by means of porous volume, pore diameters and mechanical resistance. Depending on the initial paste formulation and processing parameters, the capillary tubes showed different physico-chemical properties and structural morphology. The various results related to the capillary tubes were compared to highlight the optimum formulation and process parameters for the preparation of clay–alumina porous capillary tubes that will be used to prepare different membranes for wastewater filtration application.