New composite membranes based on PVDF fibers loaded with TiO2: Sm nanostructures and reinforced with graphene/graphene oxide for photocatalytic applications

Abstract

New composite membranes based on PVDF fibers loaded with Sm doped TiO2 (TiO2:Sm) nanostructures and graphene-based nanoparticles obtained by the electrospinning technique are reported. The addition of the inorganic nanostructures induced photocatalytic properties, while the graphene-based nanoparticles (G - graphene or GO - graphene oxide) improved the mechanical properties. Advanced instrumental methods for material analysis (e.g., XRD, SEM, mechanical, and DVS) were employed to characterize the structure and surface properties. The membranes were used in photocatalytic assays for the degradation of methylene blue (MB) under visible light irradiation. To intensify the photocatalytic processes, the effect of hydrogen peroxide addition was also investigated. The results revealed that the PVDF-based membrane containing 15% TiO2:Sm and 2.5% GO showed an optimal photocatalytic activity due to its high porosity, relevant adsorption capacity, and improved mechanical properties. The response surface methodology was employed to optimize the experimental conditions of the photocatalytic process. The addition of H2O2 significantly increased the rate constant of photodegradation reaction (k = 6.624× 10−1 min−1), disclosing a half-life of the reaction of about 1 min. This short half-life time represents a remarkable outcome for a photocatalytic process conducted under visible light irradiation. Good recycling capacity was observed for the optimal (TiO2:Sm)[15%]/PVDF/GO[2.5%] composite membrane.