RETRACTED: Preparation and characterization of multilayer mesoporous alumina nano membrane via sol–gel method using new precursors

Abstract In the present study, a mesoporous γ-alumina layer was coated on a macroporous α-alumina support via sol–gel method to produce a multilayer mesoporous alumina membrane with high performance. Different parameters like homogeneity of colloidal solution, additive, working temperature, roughness of the membrane surface, membrane thickness and porosity of the membrane were analyzed. Two types of new different solvents and additives were considered and compared to have a perfect colloidal sol. A crack-free γ-alumina membrane was obtained by adding Poly Vinyl Alcohol to the alumina solution in an optimum conditions. In order to investigate the thermal stability of the membrane, it was dried and heated up to 600 °C. The alumina sols showed particle size distributions in the range of 20–55 nm which was measured by a DLS zeta sizer. The roughness of the sub-layers was measured using a Roughness Checker and density and porosity were measured based on Archimedes principle. X-ray diffraction technique (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to characterize the membrane layer. The thickness of the produced mesoporous membrane was about 4 µm with 16 nm of surface roughness and 5 nm pore size.