Bezafibrate removal by means of ozonation: primary intermediates, kinetics, and toxicity assessment

Bezafibrate (BZF) is a lipid regulator largely used for the treatment of hyperlipidaemia. As a result of its wide use, unmetabolized BZF is released in the environment with potential toxic effects for aquatic living organisms. The results obtained in this work show that ozonation is an efficient method to degrade BZF: after 10 min of treatment (corresponding to a dose of 0.73 mmol L(-1) of ozone), the complete BZF abatement is achieved, starting from an initial concentration of 0.5 mmol L(-1). However, only a small part of the substrate is mineralized. Two different experimental approaches (absolute and competition method) are adopted to estimate the second-order kinetic constants for the ozone attack at pH=6.0, 7.0 and 8.0. A good agreement was observed between the two kinetic methods adopted. The identification of main intermediates, attempted by high-performance liquid chromatograph (HPLC)-MS technique, indicates that the oxidation of BZF develops through both the hydroxylation of the aromatic ring and the attack of ozone on the unchlorinated aromatic one. The assessment of by-products biodegradability and acute toxicity demonstrates that ozonation is a suitable technique to improve the biodegradability and reduce the toxicity of waters containing BZF.