Preparation TiO2/Al2O3 composite hollow fibre membranes

Aluminium oxide (Al2O3) hollow fibres were prepared by a combined phase inversion/sintering method. An organic binder solution (dope) containing suspended Al2O3 powders is spun into a hollow fibre precursor, which is then sintered at elevated temperatures. In spinning the hollow fibre precursor, polyethersulfone (PESf), N-methyl-2-pyrrolidone (NMP) and polyvinylpyrrolidone (PVP) were used as a polymer binder, a solvent and an additive, respectively. The prepared Al2O3 hollow fibre membranes with suitable surface roughness were then used as substrates for the fabrication of porous or dense TiO2/Al2O3 composite membranes via direct deposition using an aqueous solution containing titanium tetrafluoride. The prepared Al2O3 substrates and the TiO2/Al2O3 composite hollow fibre membranes were characterized using scanning electron microscope (SEM), X-ray diffraction (XRD) and gas permeation techniques. The results indicate that TiO2-based hollow fibre membranes, consisting of small anatase nano-particles, exhibit excellent adhesion to the outside surface of the tailor-made Al2O3 hollow fibre substrates.