Electrospinning preparation of TPU/TiO2/PANI fiber membrane with enhanced dye degradation and photocatalytic Cr(VI) reduction

The efficient elimination of toxic dye and Cr(VI) from wastewater by photocatalysis is still a challenge due to the unsatisfactory photocatalytic efficiency and difficult separation of the photocatalyst. Herein, the thermoplastic polyurethane (TPU) fiber membrane was prepared by electrospinning and then titanium dioxide (TiO2) nanoparticles were loaded on the fiber membrane by ultrasonic-assisted method, followed by in-situ polymerizations of polyaniline (PANI) on the surface of the membrane. The synergistic effect of TiO2 and PANI results in faster charge migration and more efficient separation of photogenerated charge carriers. Photocatalytic experiments revealed that TPU/TiO2/PANI fiber membranes were highly efficient for dye degradation and Cr(VI) reduction under visible light irradiation. 99.7 % of Congo red was degraded by TPU/TiO2/PANI membrane within 30 min, and the reaction rate reached 0.2 min−1. The Cr(VI) reduction efficiency was up to 99.0 % within 25 min with a reaction rate of 0.128 min−1. Additionally, the TPU/TiO2/PANI membrane exhibited a low loss in catalytic activity even after recycling 10 times, suggesting superior recycling stability compared to TPU/TiO2 membrane. The result of the electron spin resonance (ESR) experiment showed that superoxide radicals (-O2-) and hydroxyl radicals (-OH-) were involved in the photocatalytic degradation process. The prepared TPU/TiO2/PANI fiber membrane combined with excellent photocatalytic capacity, good stability and easy recovery makes it a good candidate for removing dye and Cr(VI) from wastewater.