Electrospinning of PVP-based ternary composites containing SiO2 nanoparticles and hybrid TiO2 microparticles with adsorbed superoxide radicals

The manufacturing of non-woven fibrous composites by electrospinning is being spread in catalysis, adsorption and water purification applications. Specifically designed fillers are required to boost the performances of such electrospun materials and achieve additional functionalities. Herein, silica nanoparticles (SiO2NP) and TiO2-acetylacetonate (TiO2acac, hybrid titania) microparticles (up to 90 μm) were synthesized by the sol-gel route and electrospun with poly(vinylpyrrolidone) (PVP) to obtain ternary composite mats. Different amount of hybrid titania microparticles was used to study its influence on the electrospinning performance. Analysis of ternary composite mats by spectroscopy (FTIR, EPR) and microscopy (SEM, TEM) confirmed the successful inclusion of large TiO2acac microparticles into the nanofiber matrix. Surface charge was measured by Zeta potential to evaluate the effect of hybrid titania on the surface chemistry of the composite mats. EPR analysis proved the presence of stable superoxide radicals on the ternary mat generated by TiO2acac microparticles. The silica backbone of the fibers allowed to achieve water-resistance, whereas the surface-stabilized superoxide radicals guaranteed oxidative degradation activity even under dark. This led to enhanced removal of methylene blue, with an initial rate ∼70% higher compared to a binary composite mat containing only SiO2NP as filler. This preliminary study highlights the possible application of PVP/SiO2NP/TiO2acac mats as promising membranes for oxidation processes.