Degradation of carbamazepine by the photo-Fenton process. Approach towards the elucidation of degradation by-products

Abstract

Carbamazepine (CBZ) is a pollutant of emerging concern because of its adverse effects associated. This work deals with the degradation of 1 mg L-1 of CBZ by the photo-Fenton process in water to discern the potential of this advanced oxidation process for the elimination of this persistent pollutant. For this purpose, the operating conditions were optimized using a central composite design of experiments, testing the influence of ferrous ion (Fe2+) and hydrogen peroxide (H2O2) concentrations on the degradation of CBZ. As a result, 96.4% of CBZ removal was obtained under optimal operating conditions (0.750 mg L-1 and 0.2 mg L-1 of H2O2 and Fe2+, respectively). In addition, the effect of the initial concentration of the target drug on the oxidation capacity of the photo-Fenton process was assessed by analyzing the removal kinetic constant. This value was achieved through a pseudo-first order model and resulted to be 0.0182 µmol L-1 min−1. Additionally, the degradation of CBZ in surface water was evaluated, obtaining an elimination of 74.4%. Finally, the identification of some CBZ by-products was carried out, being one of them purified and elucidated by means of the nuclear magnetic resonance technique and mass spectrometry. The referred degradation by-product was identified for the first time as 2,2′-aminodibenzaldehyde. In this regard, the photo-Fenton process is concluded to be able of degrading CBZ in natural surface water.