Application of Fenton, photo-Fenton, solar photo-Fenton, and UV/H2O2 to degradation of the antineoplastic agent mitoxantrone and toxicological evaluation

In the present study, selected advanced oxidation processes (AOPs)-namely, photo-Fenton (with Fe2+, Fe3+, and potassium ferrioxalate-FeOx-as iron sources), solar photo-Fenton, Fenton, and UV/H2O2-were investigated for degradation of the antineoplastic drug mitoxantrone (MTX), frequently used to treat metastatic breast cancer, skin cancer, and acute leukemia. The results showed that photo-Fenton processes employing Fe(III) and FeOx and the UV/H2O2 process were most efficient for mineralizing MTX, with 77, 82, and 90 % of total organic carbon removal, respectively. MTX probably forms a complex with Fe(III), as demonstrated by voltammetric and spectrophotometric measurements. Spectrophotometric titrations suggested that the complex has a 2:1 Fe3+:MTX stoichiometric ratio and a complexation constant (K) of 1.47 x 10(4) M-1, indicating high MTX affinity for Fe3+. Complexation partially inhibits the involvement of iron ions and hence the degradation of MTX during photo-Fenton. The UV/H2O2 process is usually slower than the photo-Fenton process, but, in this study, the UV/H2O2 process proved to be more efficient due to complexing of MTX with Fe(III). The drug exhibited no cytotoxicity against NIH/3T3 mouse embryonic fibroblast cells when oxidized by UV/H2O2 or by UV/H2O2/FeOx at the concentrations tested.