Photodegradation of Carbamazepine, Ibuprofen, Ketoprofen and 17 alpha-Ethinylestradiol in Fresh and Seawater

Photodegradation of four pharmaceuticals (i.e. carbamazepine, ibuprofen, ketoprofen and 17 alpha-ethinylestradiol) in aqueous media was studied using a solar light simulator (Xe lamp irradiation) and sunlight experiments. These experiments were carried out in river and seawater and compared to distilled water. The latter was used to evaluate the direct photodegradation pathways. Irradiation time was up to 400 min and 24 days for the solar light simulator and sunlight assays, respectively. Pharmaceutical photodegradation followed a first-order kinetics and their half-lives calculated in every aqueous matrix. Moreover, the sensitizing effect of DOC was evaluated by comparison with the kinetics obtained in distilled waters. Ketoprofen was rapidly transformed via direct photolysis in all the waters under both sunlight (t(1/2) = 2.4 min) and simulated solar light simulator test (t(1/2) = 0.54 min). Under xenon lamp radiation, ibuprofen and 17 alpha-ethinylestradiol were photodegraded at moderate rate with half-lives from 1 to 5 h. Finally, carbamazepine had the lowest photodegradation rate (t(1/2) = 8-39 h) attributable to indirect photodegradation. Indeed, its elimination was strongly dependent on the DOC concentration present in solution. Finally, several ketoprofen photoproducts were identified and plotted against solar light simulator irradiation time. Accordingly, the photodegradation pathway of ketoprofen was postulated.