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

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 & mu;mol 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 byproducts 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 & PRIME;-aminodibenzaldehyde. In this regard, the photo-Fenton process is concluded to be able of degrading CBZ in natural surface water.