No abstract

Mono- (Au, Ag and Cu) and bi-metallic (Au-Ag and Au-Cu) nanoparticles were deposited on TiO and tested for the photocatalytic degradation of sulfamethoxazole using either UV-C or simulated sunlight. The optimal loading of metallic nanoparticles was determined as 1.5 wt% for Au and Ag, and 1.0 wt% for Cu. In the case of bi-metallic nanoparticles, only the ratio 1:0.5 wt% for both Au-Ag and Au-Cu was tested. In experiments using UV-C light, the highest degradation performance was found for Ag/TiO, while bi-metallic nanoparticles supported on TiO also showed increased photocatalytic activity compared with unmodified TiO. In simulated sunlight irradiation tests, Au/TiO showed to be the most efficient material. Complete mineralization of sulfamethoxazole was achieved when surface-modified materials were tested in both UV-C and simulated sunlight experiments. Photolysis was efficient to fully degrade sulfamethoxazole, although mineralization was lower than 10% for both luminic sources. The main by-products of sulfamethoxazole were determined in photolysis and photocatalysis tests using UV-C light, and degradation paths were proposed. By-products showed non-toxicity and low antibiotic activity. Reuse of the catalysts upon three reaction cycles did not result in the loss of activity.

Metallurgical slags are a mass-produced industrial solid waste, often destined to landfills; the volumes disposed represent an environmental burden. Over the last three decades, applications have been found for these wastes, mainly as a low-cost additive in building materials. More recently, their unique chemical properties have attracted attention to produce high-added-value materials for environmental applications, to be used as adsorbents, catalysts, or a source of reactive species in environmental engineering. Such uses can be classified as a function of the added value generated, technological complexity, and environmental impact. This review will focus specifically on the modification and use of slags for catalysis, photocatalysis, and photocatalytic production of hydrogen, which have received relatively little attention in literature. A summary will be presented about the general requirements for using unmodified slags as well as slag processed under alkaline or acidic conditions for advanced oxidation processes. Then, an overview will be given of the use of slags as photocatalysts in water treatment, organized according to the origin of the product (steel, copper, magnesium, ferromanganese), as well as emerging reports on the photocatalytic production of hydrogen, in contrast to the use of highly specific titania-based products developed for the same purpose.

La efectiva eliminación de agentes contaminantes en el agua es un tema de prioridad en todo el mundo. Muchas de estas sustancias contaminantes son recalcitrantes en los sistemas convencionales de tratamiento de agua, por lo que un importante número de sistemas de tratamiento avanzado ha sido desarrollado. Los procesos de oxidación avanzada, como la fotocatálisis heterogénea, han demostrado eliminar eficientemente un amplio grupo de agentescontaminantes de carácter orgánico, inorgánico y microbiológico presentes en el agua contaminada. En este artículo se revisan los principios básicos del proceso de fotocatálisis heterogénea, así como los mecanismos involucrados en la degradación de contaminantes de diferente tipo en el agua. Adicionalmente, se hace una revisión del impacto que puede tener la modificación en superficie de semiconductores sobre la eficiencia de los procesos fotocatalíticos.