Kinetics and pathways of Bezafibrate degradation in UV/chlorine process

UV/chlorine, as a novel disinfection method, has attracted great interest due to its effective removal for pathogenic microorganism and degradation of trace organic contaminants existed in water environment. This paper investigated the degradation kinetics and pathways of Bezafibrate (BZF), a typical antilipemic drug, during UV/chlorine process. The results showed that 92.3% of BZF was degraded after 20 min in UV/chlorine process. This indicated HO center dot and reactive chlorine species (RCSs) formed in UV/chlorine played the dominant role in degrading BZF. Observed rate constants of BZF degradation (k (obs,BZF)) in UV/chlorine process increased linearly in a wide chlorine dosage from 0.1 to 1.0 mM, which implied that ClO center dot generated from the reactions of chlorine with HO center dot and Cl center dot could react with BZF rapidly. The steady-state kinetic modeling result proved this deduction and the rate constant of ClO center dot with BZF was fitted to be 5.0 x 10(8) M-1 s(-1). k (obs,BZF) was affected by Cl- and HA. The total contribution of RCSs (including Cl center dot, Cl-2 center dot(-), and ClO center dot) to the degradation of BZF was determined to be similar to 80%, which is much higher than that of HO center dot. Thirteen degradation products of BZF were identified by LC-MS/MS. Initial degradation products were arisen from hydroxylation, chlorine substitution and cyclization by HO center dot and RCSs, and then further oxidized to generate acylamino cleavage and demethylation products.