Fe3O4 nano-octahedra/Vulcan XC72: Optimization and combination with solar-based electro-fenton for progestins degradation.
Description
The widespread presence of synthetic progestins, such as levonorgestrel (LNG) and gestodene (GES), in aquatic environments poses significant ecotoxicological risks due to their endocrine-disrupting properties. In this study, nano-octahedral magnetite (Fe3O4-NO) was synthesized via a hydrothermal route and incorporated into gas diffusion electrodes (GDEs) supported on Vulcan XC72 to enhance the in-situ electrogeneration of hydrogen peroxide (H2O2). High-resolution Transmission Electron Microscopy, X-ray diffraction, SEM, X-ray photoelectron spectroscopy, and contact angle measurements thoroughly characterized the physicochemical and morphological properties of the materials. 3% Fe3O4-NO/C provided a 2-fold increase on H2O2 selectivity in comparison with Vulcan XC72. Electrochemical performance was optimized using a 23 factorial design and principal component analysis (PCA), with current density, pH, and Na2SO4 concentration as variables. The optimized GDE (3% Fe3O4-NO/C) achieved a maximum H2O2 production of 0.44 ± 0.02 g L⁻¹ with a current efficiency of 43.1 ± 0.23% and a specific energy consumption of 0.012 ± 0.009 kWh g⁻¹. The electrode was further applied to the degradation of LNG and GES using solar and anodic-assisted electro-Fenton processes. Under optimal conditions, over 70 % removal of both progestins was achieved, with stable performance across three operational cycles. These findings demonstrate the potential of 3% Fe3O4-NO/C-GDEs as efficient, reusable cathodes for sustainable electrochemical advanced oxidation processes (EAOPs) in water treatment.