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Solar driven degradation of 17β-estradiol using composite photocatalytic materials and artificial irradiation source: Influence of process and water matrix parameters

The study is focused on applicability and effectiveness of solar driven photocatalytic treatment of 17β-estradiol (E2), estrogenic hormone recently included in the watch list of priority substances within EU Water Framework Directive. In that purpose, the immobilized TiO2 based composites, made by coupling TiO2 and iron- exchanged zeolite of ZSM5 type (TiO2-FeZ) or another semiconducting material (TiO2-SnS2), were applied as solar active photocatalysts. The applied materials were investigated for their surface, morphology, structure and optical properties using BET method, X-ray diffraction (XRD), scanning electron microscopy / energy- dispersive X-ray spectroscopy (SEM/EDX) and diffuse reflectance spectroscopy (DRS). It was found that TiO2-FeZ has significantly higher specific surface area than TiO2-SnS2, while XRD analyses revealed the presence of crystalline phases of catalyst particles only (TiO2, FeZ and SnS2). SEM/EDX indicated the inhomogeneity of prepared composite films, while DRS showed that composites have lower band gaps comparing to TiO2, which decreased gradually with increasing the wt% of FeZ or SnS2 within composites. The influence of solar driven photocatalytic treatment parameters: pH, [H2O2] and composite formulation, on the effectiveness of E2 degradation was investigated employing response surface modeling. E2 degradation achieved by solar/TiO2-FeZ/H2O2 process (78.1%) was significantly higher comparing to reference process using AEROXIDE TiO2 P25 (41.3%), as well as to that obtained by solar/TiO2-SnS2 and solar/TiO2-SnS2/H2O2 processes (51.0 and 34.4%, respectively). The influence of real water matrix constituents ; natural organic matter (NOM), nitrates and carbonates, on the effectiveness of E2 degradation by solar/TiO2-FeZ/H2O2 process was investigated as well. It was found that E2 degradation enhanced in the presence of NOM, while the inhibitory effect was observed in the case of nitrates and carbonates presence.

water pollution ; 17β-estradiol ; solar photocatalysis ; TiO2-based composites ; water matrix

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