Efficiency of blue-glass-metal oxides immobilized system in the photodegradation of different pharmaceutical compounds

Kinetics of photodegradation and photoproducts identification of different pharmaceutical compounds in water were determined in laboratory experiments using light irradiation with a solar simulator in presence either of titanium dioxide (TiO2) in aqueous suspension or metal oxides immobilized on blue-glass surface. Pharmaceutical compounds have been recently classified as priority risk pollutants. The photodegradation of pharmaceuticals in water solution catalyzed by TiO2 has been extensively studied in the past few years with good results [1,2]. Despite the usage of this semiconductor as catalyst for environmental applications has proved very effective, one main problem of using TiO2 is the separation of the powder in the aqueous media after the photocatalytic process. To avoid this problem, TiO2 and other metal oxides used as photocatalysts have been supported in a variety of materials [3,4], although the surface area of the photocatalyst decreases greatly as a result of the immobilization, and the supported photocatalysts usually show poor performance. By using metal oxides immobilized on blue-glass surface is possible to keep out an enough active surface, but at the same time the separation of the catalyst becomes an easy procedure. The aim of our research is to compare the effectiveness of blu-glass photocatalyst to TiO2 suspension to photo-degrade some pharmaceutical compounds. The photodegradation reaction of tested compounds using blue-glass-TiO2 was very slow by comparison to TiO2 powder, while the kinetics of photo-reactions was greatly enhanced when a series of other metal oxides was used to prepare the blue-glass system. Our final results showed that the photocatalysts tested in the experiments are able to degrade the pharmaceuticals used as model molecules and may find application in the remediation of water contaminated with recalcitrant residues due to poor efficiency of treatment plants normally adopted for the purification of wastewater. It could be useful to design a suitable pilot reactor to be tested in outdoor experiments using solar irradiation. In our opinion the metal oxides glass-immobilized system may be a suitable tool to be placed upstream of a normal wastewater treatment plant.