Water pollution from emerging contaminants (ECs) or emerging pollutants is an important environmental problem. Heterogeneous photocatalytic treatment, as advanced oxidation treatment of wastewater effluents, has been proposed to solve this problem. In this paper, a heterogeneous photocatalytic process was studied for emergent contaminants removal using paracetamol as a model contaminant molecule. TiO2 photocatalytic activity was evaluated using two photocatalytic reactor configurations: Photocatalyst solid suspension in wastewater in a stirred photoreactor and TiO2 supported on glass spheres (TGS) configuring a packed bed photoreactor. The surface morphology and texture of the TGS were monitored by scanning electron microscope (SEM). The influence of photocatalyst amount and wastewater pH were evaluated in the stirred photoreactor and the influence of wastewater flowrate was tested in the packed bed photoreactor, in order to obtain the optimal operation conditions. Moreover, results obtained were compared with those obtained from photolysis and adsorption studies, using the optimal operation conditions. Good photocatalytic activities have been observed and leads to the conclusion that the heterogeneous photocatalytic system in a packed bed is an effective method for removal of emerging pollutants. OPEN ACCESSCatalysts 2015, 5 78

We have explored the emerging and ground-breaking photonics approach to enhance the photocatalytic activity of one of the main semiconductor electrodes used in water-splitting reactions, titanium dioxide (TiO 2 ): the blue shifting of the incident radiation by means of a highly efficient up-conversion by a rareearth (RE) doped luminescent material to assist in the harvesting of long wavelengths in unused portions of infrared light. We present an up to 20% improvement of the photocatalytic action of the commercial benchmark TiO 2 efficient photocatalyst in the decomposition of methylene blue in water under Xe-lamp irradiation, and also an outstanding enhancement by a factor of about 2.5 of the photolytic degradation rate of this pollutant. Our results prove that the ultraviolet (UV) radiation that reaches the TiO 2 particles is increased by the addition of the RE-doped powder material into a slurrytype photo-reactor, boosting both the photocatalytic and photolytic degradation rates. Thus, we show the feasibility of handling and transforming the incoming infrared radiation, bridging the UV gap of the photocatalytic semiconductor. Let us turn the infrared into the blue; there is plenty of energy at the bottom.

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