Colour changes during the carbamazepine oxidation by photo-Fenton

Oxidation of waters containing 50.0 mg L-1 of carbamazepine was conducted by a photo-Fenton reagent employing a UV lamp of 150W, at pH=3.0 and T=40°C. The oxidising action of hydrogen peroxide was studied in a range between [H2O2]0=0-15.0 mM. When applying stoichiometric ratios of 2 mol C15H12N2O:20 mol H2O2:1.8 mol Fe2+, the maximum formation of colour (0.381 AU) is promoted. The colour may be generated by by-products of degradation of carbamazepine that have chromophore groups in its internal structure, such as oxo and dioxo-carbazepines, which would generate colour during the first minutes of oxidation, while the formation of acridones would slowly induce colour to the water.