Fabrication of nanostructured TiO2 hollow fiber photocatalytic membrane and application for wastewater treatment

• A facile spinning–sintering method is developed for the TiO2 hollow fiber membrane.
• Concurrent separation and photocatalytic oxidation are achieved by the membrane.
• Calcination temperature is the key factor of the membrane properties.
• The membrane fouling is alleviated by the photocatalytic oxidation.

Nanostructured TiO2 hollow fiber photocatalytic membranes were fabricated in this study via a facile spinning–sintering method. The morphology, crystal phase, porosity and mechanical strength of the membranes were characterized by SEM, XRD, N2 sorption and bending test, respectively. The dimensions of the sintered hollow fibers are approximately 1.0–1.2 mm in the outer diameter and 150 μm in thickness. Finger-like macrovoids and sponge-like mesopores form inside the membranes whilst the TiO2 layer is denser near the outer wall of the membranes. The calcination temperature has a significant impact on the properties of the membranes. With increasing the calcination temperature, the pore size and photocatalytic activity decrease while the mechanical robustness increases. The photocatalytic activity, permeability and separation efficiency of the membranes were evaluated using both Acid Orange 7 (AO7) and raw sewage as pollutants. The membrane calcined at 900 °C has a good balance between mechanical properties and photocatalytic activity. A high organic removal rate of 90.2% is achieved by the filtration and photodegradation functionalities of the membrane. The water flux of 12.2 L m−2 h−1 for the membranes exposed UV irradiation is 2.2 times higher than that in the absence of it, which indicates lower levels of membrane fouling. The results provide vital insights into the development of photocatalytic membranes and their applications in water treatment.