TiO2 photocatalysis under natural solar radiation for the degradation of the carbapenem antibiotics imipenem and meropenem in aqueous solutions at pilot plant scale.

This paper deals with the removal of two last-resort antibiotics, namely imipenem and meropenem, in aqueous solutions employing heterogeneous photocatalysis with TiO2 under natural solar radiation at pilot plant scale. It was found that TiO2 photocatalysis is a very efficient technique for the degradation of both compounds in aqueous solutions, albeit it's relatively low quantum efficiency. At the experimental conditions employed in the present work (compound parabolic collectors photoreactor) the optimal TiO2 concentration was about 50 mg L-1. Experiments conducted in various aqueous matrices lead to the conclusion that the method can be applied to real aqueous matrices, such as natural waters and wastewaters. The comparison of TiO2 photocatalysis and natural photolysis showed an important decrease of the accumulated energy required to achieve the complete removal of both antibiotics which, in terms of normalized illumination time (t30W), represented a reduction of 50 min for imipenem and 60 min for meropenem.