In-situ immobilization of titanium dioxide on poly (ether ether ketone) hollow fiber membranes and the effect of pH level on the photo-removal process of dyes

In order to prevent secondary pollution due to the photocatalyst titanium dioxide (TiO2) used in industrial wastewater treatment, and to boost the photo-removal efficiency TiO2 was immobilized on the surface of high-performance poly (ether ketone) (PEEK) hollow fiber membrane via an in-situ grafting reaction. γ-Methylacryloyloxypropyltrimethoxysilane (MAPS) was used as a coupling agent to link the PEEK hollow fiber membranes with TiO2 under UV radiation and hydrothermal treatment. The surface chemical structure, surface morphologies, and permeability of the PEEK-PMAPS-TiO2 membranes were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and the water flux test. The performance of PEEK-PMAPS-TiO2 membranes in terms of their ability to accelerate the photo-removal of different dyes was investigated under a range of pH conditions. Experimental results showed that the photo-degradation efficiency for tartrazine can be reached 100% (after 4 h of UV radiation at pH of 3.5) with a TiO2 grafting degree of 15.56 wt% on the composite membranes. We also find that the acidic/alkaline condition accelerates the processes of absorption and photo-removal of negatively/positively charged dyes. In addition, the recyclability of the PEEK-PMAPS-TiO2 membrane was also investigated. After refreshing treatment, the second photo-removal efficiency still reached over 95%.Graphical abstract