Synthesis and characterization of a new inorganic ultrafiltration membrane composed entirely of Tunisian natural illite clay

New ceramic multilayer membranes with a top layer of Tunisian natural illite clay were prepared. The illite powder (fine fraction less than 2 µm in size) was isolated by sedimentation from crude clay. The obtained powders of a specific surface area of 160 m2g–1 were analyzed by X-ray diffraction (XRD). It was found that the principal material of this sample was illite. The deposition of the ultrafiltration layer occurred by slip casting method on aclay microfiltration layer using aqueous colloidal suspension. After drying at room temperature for 24 h, the ultrafiltration layer was heated to 800°C. SEM analyses showed that very thin defect-free top layers were formed. The layer thickness increased with dipping time but could be limited to a few micrometer (4.82 µm). The membrane was further tested for ultrafiltration of dextran polymer solution of different molecular weights. The membrane cut-off was of 185 KDa and the water permeability was equal to 88 l.h–1m–2 bar–1.