Tecnologias alternativas para remoção de contaminantes emergentes em meio aquoso

Abstract

The first chapter of this work includes the synthesis and characterization of new catalysts based on the use of titanium dioxide supported on autoclaved cellular con-crete (ACC), Nb2O5 (niobium oxide) and treated powder bone (hydroxyapatite). The evaluation of the photocatalytic potential of the material was performed by applying them in the degradation of emerging organic contaminants in aqueous solution. The molecules chosen to represent these contaminants: indigo carmine (a dye), diclo-fenac (a drug) and atrazine (a pesticide). These compounds are found in urban and industrial wastewater. The catalytic process was monitored and quantified by differ-ent techniques. Mass spectrometry electrospray ionization (ESI-MS) was used to monitor the degradation of the target molecules and to identify the major degradation products after the photocatalytic process. From the results obtained by ESI-MS, it was possible propose mechanisms for the degradation for each molecule. High per-formance liquid chromatography (HPLC) was used to monitor and quantify the deg-radation of the target molecules. With the results obtained by this technique it was possible to investigate the kinetic of each system. Total organic carbon (TOC) meas-urements were used to determine the mineralization rates obtained after the photo-catalytic process. One of the three materials prepared (TiO2/ACC), wich possessed floating properties, was employed in a simulated real situation and its photocatalytic activity shown to be higher than that of the commercial p25 TiO2. Lastly, the toxicities of the solutions before and after the photocatalytic process (for 120 min of exposure) were assessed in tests against Artemia Salina. Hece, degraded solution of two targer compounds (indigo carmine and diclofenac) presented no higher toxicities the than the original solutions. On the other hand, the toxicity of the degraded solution of atra-zine was reduced by 50% in comparison to the primary solution. In the second chapter of this work, niobate composites of titanium/nickel and tita-nium/copper prepared via solid synthesis. Although these composites had no high surface area, they presented good photocatalytic activity (superior to that of photoly-sis with UV radiation) in the degradation of indigo carmine.