Sol–gel synthesis and characterization of defect-free alumina films and its application in the preparation of supported ultrafiltration membranes

Alumina, being an excellent technological material, is selected as the material of synthesis by sol–gel route, as it shows interesting properties having wide array of industrial and engineering applications. In defect-free synthesis of alumina film, the parameters such as concentration of ‘Al’ in the alkoxy-hydrosol of alumina, drying of hydrogel, and calcination of dried film were optimized. The optimized process and parameters were applied in sol–gel synthesis of supported alumina membrane. BET, TGA, FTIR, Raman spectroscopy, and SEM/TEM techniques were used for characterization of alumina membrane. X-ray diffraction studies reveal evolution of crystalline state from amorphous state i.e. from ‘γ’ to ‘α’ phase of alumina. The AFM results of calcined alumina (1100 °C) showed the cylindrical finger-like structures, open at both the ends. Water permeation studies were performed to assess hydrodynamic flux of membrane. The result obtained by N2 adsorption studies has been used to predict water permeability of membrane. It was compared and modelled with experimental results.