[Photochemical degradation of ofloxacin in aqueous solution]

The photodegradation of ofloxacin (OFLX) was investigated in distilled water, artificial seawater and natural seawater exposed to high-pressure mercury lamp and xeon lamp. The photolysis of OFLX was affected by various factors including light sources, initial concentrations, acetone and surfactants. The photoreaction rate of OFLX under high pressure mercury lamp was much faster than that under xeon lamp, conforming to the first-order kinetics behavior. Expose to the same light intensity, The photodegradation rate of OFLX was the quickest in natural seawater, followed by artificial seawater. The initial concentrations of OFLX were 2, 4 and 6 mg x L(-1), the rate constants were 0.163, 0.140 and 0.132 min(-1), respectively. The photodegradation rates of OFLX in seawater decreased along with its initial concentration. The addition of acetone could accelerate the photoreactions of OFLX, The constants of the reaction rate range from 0.084 2-0.102 min(-1). A positive correlation was found between the photosensitive efficiency and the added concentration of acetone. On the contrary, the addition of cetyl trimethyl ammonium bromide (CTAB), sodium dodecyl benzene sulfonate(SDBS) and Tween-20 (TW-20) inhibited the photodegradation of OFLX, of which concentrations were all 5 mg x L(-1). In addition, toxicity tests with Isochrysis galbana 8701 showed higher risk of intermediate products generated from photolysis of OFLX. The toxicity of products decreased along with the reaction.