Composite ceramic membranes from natural aluminosilicates for microfiltration applications

This work concerns to the development and characterisation of support, active layer and tubular composite membranes (CM) from natural aluminosilicates as principal components (clay, bentonite, feldspar, quartz, alumina). The selection of these raw materials was primarily based on their low cost and they are locally produced. In the substrates preparation, the effect of materials compositions, additives, particle sizes, paste rheological properties, and drying-sintering temperatures was investigated. The consolidated ceramic substrates were characterised by SEM, DTA–TG, X-Ray diffraction, Hg intrusion, mechanical resistance, and water flux measurements. Extrusion has been used as the forming process of tubular support. The CM was fabricated depositing a thin active layer by slip-casting method on the support. The CM sintered at 1200 °C showed the best structural characteristics, porosities of 50%, active layer pore size between 0.08 and 0.55 μm. The CM hydraulic permeabilities (10–274 L/h m2 kPa) were comparable and greater than several inorganic commercial membranes and CM obtained from other researches. The CM microfiltration effectiveness was tested with different substances from food industry, i.e. slaughterhouse wastewater treatment and goat milk pasteurisation. The obtained results, insoluble residue rejections (100%) and high bacterial removal (87–99%), make the ceramic CM suitable for microfiltration processes.