Degradation of benzophenone-3 by the ozonation in aqueous solution: kinetics, intermediates and toxicity.

Abstract

Benzophenone-3 (BP-3) is a popular ultraviolet absorbing chemical and has an adverse impact on aquatic ecosystems and human health. We determined the reaction kinetic constants of BP-3 and its de-proton pattern reacting with the molecular ozone or hydroxyl radical (·OH) for the first time. The obtained constant of the molecular ozone reacting with BP-3 or BP-3(-) was 1.03(±0.21) × 10(2) or 1.85(±0.098) × 10(5) M(-1)s(-1), respectively. And, the constant for BP-3 reacting with ·OH was 9.74(±0.21) × 10(9) or 10.13(±0.25) × 10(9) M(-1)s(-1) as using 4-chlorobenzoic acid and benzotriazole as reference compounds, respectively. The intermediates generated in the molecular ozone (12 kinds) or ·OH oxidation (18 kinds) were identified by LC-MS/MS. The removal efficiency of BP-3 in ozonation was dependent on the initial concentration of ozone, BP-3, and matrix water quality. The detoxification of BP-3 ozonation was depended on initial ozone dose using Chlorella vulgaris as the probe. Higher ozone dose increased the toxicity of the solution for more BP-3 being degraded and more intermediates formed, suggesting that the sole ozonation is not an effect approach for the degradation of BP-3 and some other energy should be combined.