The combination of the catalytic properties of Al₂O_3/TiO₂ formed an efficient system to degrade the ubiquitous pollutants TPA and PET. The coating (Al₂O₃)_0.75TiO₂ was characterized by X-ray diffraction. Stainless steel disks with photo-catalyst coating were placed transversely in a 3.0 L vertical glass reactor with ascending airflow for supplying oxygen to the reaction medium and visible light lamps for photo-activation. The analysis of the coating homogeneity, morphology and particle size distribution of the TiO₂ coatings and (Al₂O₃)_0.75TiO₂ system were confirmed by SEM. Optical properties and band-gap energy were calculated by using the Tauc equation. UV–Vis spectrophotometry (UV–Vis) and chemical oxygen demand (COD) were the quantitative techniques to measure the reduction in the initial TPA and PET concentrations.

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.

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.

The combination of the catalytic properties of Al2O3/TiO2 formed an efficient system to degrade the ubiquitous pollutants TPA and PET. The coating (Al2O3)0.75TiO2 was characterized by X-ray diffraction. Stainless steel disks with photo-catalyst coating were placed transversely in a 3.0-L vertical glass reactor with ascending airflow for supplying oxygen to the reaction medium and visible light lamps for photo-activation. The analysis of the coating homogeneity, morphology and particle size distribution of the TiO2 coatings and (Al2O3)0.75TiO2 system were confirmed by SEM. Optical properties and band-gap energy were calculated by using the Tauc equation. UV-Vis spectrophotometry (UV-Vis) and chemical oxygen demand (COD) were the quantitative techniques to measure the reduction of the initial TPA and PET concentrations.

En el presente, se explora el efecto que tiene la relación molar Al2O3:TiO2 en las propiedades fisicoquímicas y ópticas del sistema (Al2O3)xTiO2 sintetizado por la técnica sol-gel con x=0, 0.5, 0.75 y 1.0, y en la eficiencia para degradar azul de metileno (AM) por fotocatálisis heterogénea. Por DRX se identificó la estructura rutilo para el TIO2 (x=0) y en el sistema (Al2O3)xTiO2, se identificaron las estructuras anatasa y α-alúmina para el TiO2 y Al2O3 respectivamente. La proporción x=0.75 mostró la mejor eficiencia de fotodegradación del AM, 43.5% en 6 h, al ser la única muestra que absorbe en el rango visible de 400 a 650 nm, y presenta baja aglomeración de partículas esféricas con distribución media de tamaño de 0.25 μm (~250 nm). La degradación del AM empleando TiO2, (Al2O3)0.5TiO2 y (Al2O3)TiO2 fue de 11.4%, 22.8% y 24.9% respectivamente.

En este trabajo se caracterizaron polvos de cobre y óxido de zinc embebidos en una matriz de dióxido de silicio. La relación molar de los polvos de ZnO y Cu fue de 2:1. Las propiedades antibacteriales conjuntas del ZnO y del Cu y la naturaleza semiconductora del ZnO favorecen la inhibición de microorganismos por estrés oxidativo y lisis celular; adicionalmente se favorece la transformación de compuestos volátiles indeseables por fotocatálisis. Las partículas de Cu se obtuvieron por reducción química y las nanopartículas de ZnO por la técnica hidrotermal. La espectroscopia infrarroja reveló bandas de absorción a 510 cm-1, 1100 cm-1 correspondientes a los enlaces Zn-O y Si-O, respectivamente. Por difracción de rayos X se observa la presencia de la fase Wurzita del ZnO. Los patrones de difracción del cobre Cu muestran los picos característicos de la estructura cúbica centrada en las caras.