EMPLOYMENT OF PHOTOLYTICAL AND PHOTOCATALYTICAL METHODOLOGIES FOR REMOVAL OF CEPHALEXIN IN AQUEOUS SOLUTION

Abstract

The increasing contamination of water bodies by the presence of pharmaceutical actives present in medicinal products for human and veterinary use has led to serious environmental consequences, such as the emergence of resistant bacterial strains. β-lactam antibiotics, a class of which is cephalexin (CPX), is one of the most commonly found contaminants in natural waters. Aiming to determine the best conditions for the photodegradation of this active in aqueous solution, the photolytic and photocatalytic methods were investigated. For the photocatalytical experiments employing homogeneous (H2O2) and heterogeneous (TiO2) catalysts, the parameters were organized according to an experimental design 23, with the objective of observing the influence of each factor in the process, as well as the interaction between them in the different pHs studied. From the analysis of the results it was possible to verify that the parameters pH, H2O2, as well as the interaction between the parameters H2O2 and TiO2 are significant for the process, and that the best conditions for the photocatalysiswere pH 4, [TiO2] = 50 mg L-1 and [H2O2] = 1000 mg L-1. In the antimicrobial activity assay, only two strains, E. coli and A. hydrophila, showed no sensitivity to the photochemically treated drug, showing that in these cases the pharmaceutical active had its antimicrobial activity decreased.