Fe-doped TiO2/PVDF-HFP electrospun membranes for tetracycline photocatalytic degradation under visible light

Heterogeneous photocatalysis operated under visible light is considered an efficient and ecofriendly method to remove pharmaceuticals from water streams. However, the recovery of the nano-sized catalyst particles limits this technology to small-scale applications. In this study, we prepared Fe-doped P25 TiO₂ photocatalysts and immobilized them over PVDF-HFP electrospun membranes for the photocatalytic degradation of Tetracycline antibiotic under visible light. To ensure uniform distribution of the nanoparticles on the fibers, the electrospinning voltage and the weight percentage of TiO₂ were varied, and two preparation methods were applied to disperse the catalyst in the polymeric solution. In order to maximize the visible light exposure of the membranes, 3D printed membrane holders with square and circular shapes were designed to immerse the membrane in Tetracycline solution. The results showed that immobilizing P25 catalysts on the fibers of the membranes limited their visible light absorption when the light source was assembled on the top of the aqueous reaction medium. This occurred due to the membrane's opacity limited light penetration, resulting in uneven irradiation throughout its depth. Based on this, a new photocatalytic reactor design was proposed with immersed light illumination source to reduce the distance between the membrane and the light source for improved activation of the P25 particles. In this design, a 3D-printed vertical membrane holder was also included to accommodate a larger membrane surface area and therefore minimize the required spatial area for large industrial applications.