Preparation and characterization of TiO2 and γ-Al2O3 composite membranes for the separation of oil-in-water emulsions

Abstract

A clay based ceramic support was prepared by a uniaxial pressing method and titanium dioxide (TiO₂) and γ-alumina (γ-Al₂O₃) composite membranes were fabricated individually by coating TiO₂ and γ-Al₂O₃ particles on the prepared ceramic support via a hydrothermal method. The prepared TiO₂ and γ-Al₂O₃ powders as well as membranes were systematically characterized using analytical techniques such as thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), BET surface area, X-ray diffraction analysis (XRD), particle size analysis, scanning electron microscopy (SEM), porosity, field emission scanning electron microscopy (FESEM), N₂ gas permeation and pure water permeability. Filtration experiments were performed to evaluate the performance of the support and membranes by separation of synthetic oil-in-water emulsions. The effects of applied pressure and feed (oil) concentration on the treatment of oil-in-water emulsion for the support and membranes were examined. TiO₂ membrane demonstrates better rejection (97–99%) and permeate flux (8.48–55.13 × 10⁻⁵ m³ m⁻² s⁻¹) as compared to the support (rejection of 95–97% and permeate flux of 1.87–9.84 × 10⁻⁵ m³ m⁻² s⁻¹). Also the γ-Al₂O₃ membrane shows good rejection (96–98%) and permeate flux (6.12–22.03 × 10⁻⁵ m³ m⁻² s⁻¹). Despite similar rejection shown by the support and composite membranes, the flux of the TiO₂ membrane is one order higher than that of the support due to the enhanced hydrophilic character of the membrane after TiO₂ coating. Hence, the prepared composite membranes can be used as potential candidates for the treatment of oil-in-water emulsions.