Evelyn Y. Calvillo-Muñoz

On 304 stainless steel substrates, two combined systems based on silver particle semiconductors, Ag/TiO₂ and Ag/SiO₂, were formed. Such systems were applied in the photocatalytic degradation, profiting from sunlight, of nitrosamines, which are highly toxic substances, specifically N-Nitrosodiethanolamine. The synthesis of TiO₂ and SiO₂ was carried out by the sol–gel method with co-precipitation of Ag metallic particles, adding a quaternary-ammonium-based ionic liquid as a reducing agent. The photocatalysts were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD), confirming the integration of anatase-phase TiO₂ and amorphous-phase SiO₂ and the Ag cubic structure. The band gap width was determined by means of the Tauc graphical method, finding 1.7 eV and 1.8 eV for SiO₂ and TiO₂, respectively. The photocatalytic evaluation occurred under direct sunlight irradiation, achieving degradation efficiencies above 98% during the first 30 min; in addition, organic matter was quantified through the chemical oxygen demand (COD) technique.

On 304 stainless steel substrates, two combined systems based on silver particle semiconductors, Ag/TiO₂ and Ag/SiO₂, were formed. Such systems were applied in the photocatalytic degradation, profiting from sunlight, of nitrosamines, which are highly toxic substances, specifically N-Nitrosodiethanolamine. The synthesis of TiO₂ and SiO₂ was carried out by the sol-gel method with co-precipitation of Ag metallic particles, adding a quaternary-ammonium-based ionic liquid as reducing agent. The photocatalysts were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and x-ray diffraction (XRD), confirming the integration of anatase-phase TiO₂ and amorphous-phase SiO2 and the Ag cubic structure. The band gap width was determined by means of the Tauc graphical method, finding 1.7 eV and 1.8 eV for SiO₂ and TiO₂, severally. The photocatalytic evaluation occurred under direct sunlight irradiation, achieving degradation efficiencies above 98 % during the first 30 min; in addition, organic matter was quantified through the chemical oxygen demand (COD) technique.

The present research work describes the synthesis and characterization of CuO/SiO₂ for coating-perforated 304 stainless steel (SS) substrates to degrade methylene blue and amoxicillin under visible light irradiation. The foregoing photocatalytic system was achieved through the coprecipitation method by adding pure CuO to a SiO₂ sol at 1:5, 1:10, and 1:15 molar ratios. The conditions for carrying out the depositions on the SS substrates (three per substrate) involved an immersion rate of 90 mm/min with a drying time of 20 min at 120 °C. The XRD technique confirmed the presence of the SiO₂ amorphous phases and CuO monoclinic systems in the coatings, with a particle size distribution ranging from 0.5 to 2.5 μm (with an average of 1.26 ± 0.06 μm). As for SEM, it revealed a homogeneous coating surface without cracks. The produced photoactive CuO/SiO₂ coatings were capable of degrading methylene blue (98%) at 1500 min and amoxicillin (55%) at 450 min.