Physicochemical and photocatalytic properties of carbonaceous char and titania composite hollow fibers for wastewater treatment

This work shows the concept of a simple, single-step, partial pyrolysis approach to prepare inorganic composite hollow fibers at low temperature conditions. Two series of robust, photocatalytic and high-performance membranes were synthesized by changing the pyrolysis temperature (Series 1: 500–600 °C for 8 h) and time (Series 2: 550 °C for 3–12 h), leading to the formation of a composite matrix consisted of carbonaceous char and titania nanoparticles. Chemical composition, phase of crystallinity, mechanical strength, textural characteristics, morphology and photocatalytic activity of the hollow fibers were comprehensively characterized. Mechanical strength of the hollow fibers was found to directly attribute to the amount of char and porosity. Hollow fibers, prepared using 8 h at 550 and 575 °C or 6 h at 550 °C condition, displayed a good balance between the highest mechanical strength of 52 MPa and photo-degradation of 90.4% of acid orange 7 under ultra-violet light. This was attributed to the optimization of degree of char derived from the binder and the exposure of anatase titania nanoparticles on the hollow fiber surface made available for photo-oxidation. This work offers the opportunity for future development of a fully integrated photocatalysis and membrane operation for wastewater treatment applications.