Evaluation of ecotoxicological properties of industrial wastewater after photocatalytic treatment

Heterogeneous photocatalysis is one of the most promising technologies for an advanced degradation of emerging pollutants in water bodies, due to the widespread availability of low-cost and efficient photocatalysts. The challenge, however, is to boost the exploitation of solar light through the use of photocatalysts with improved activity under sun irradiation. Most studies on this topic focus on the enhanced photodegradation yields achieved by the incorporation of the carbon additives. However the impact of the carbonaceous additive on the toxicity of the final effluent is scarcely addressed and little is known on the nature of the intermediates formed when the photooxidation pathway is modified. In this context, the aim of this work was to evaluate the impact of the incorporation of nanoporous carbons (either as photocatalysts or additives to semiconductors) in terms of an ecotoxicity risk assessment using phenol as a model organic pollutant. In this work it was used as catalysts TiO2, CQ and composites of TiO2 with CQ. It was measured the ecotoxicity of samples after 1, 3 and 6h of photodegradation for synthetic samples of phenol and wastewater from industrial origin. The results are interpreted in terms of the ecotoxicity of the solutions obtained after the photocatalytic assays by using the bioluminescence inhibition of the bacterium Vibrio fischeri, while exploring the role of the carbon component features (i.e. structure, texture) on the performance of the semiconductor/carbon photocatalysts, TiO2 using semiconductors. For both synthetic and real wastewater samples the lower ecotoxicity values were achieved after 6 hours of irradiation with the CQ as catalyst. The results with real samples have also shown that photodegradation assays performed with hybrid semiconductor/nanoporous carbon catalysts can be more effective than the semiconductors alone or photolysis