UV-C photolysis of endocrine disruptors. The influence of inorganic peroxides

Norfloxacin, doxycycline and mefenamic acid have been photolysed with UV-C radiation (254 nm) in the presence and absence of inorganic peroxides (hydrogen peroxide or sodium monopersulfate). Quantum yields in the range (1.1-4.5) × 10−3 mol Einstein−1 indicate the low photo-reactivity of these pharmaceuticals. Inorganic peroxides considerably enhanced the contaminants conversion, although no appreciable mineralization could be obtained. A simplistic reaction mechanism for the hydrogen peroxide promoted experiments allowed for a rough estimation of the rate constant between hydroxyl radicals and norfloxacin (k > 1 × 109 M−1 s−1), doxycycline (k > 1.5 × 109 M−1 s−1) and mefenamic acid (k > 11.0 × 109 M−1 s−1).