Abstract: The ultrasonic degradation of quinolone antibiotics levofloxacin in water with CCl₄ enhancement was investigated. The effects of CCl₄ dosage, ultrasonic power, pH value and initial concentration of levofloxacin were discussed. The products were examined by HPLC and LC-MS/MS. The results indicated that the ultrasonic degradation of levofloxacin was obviously enhanced by CCl₄ addition; the degradation efficiency increased from 1.9% to 69.2% with CCl₄ dosage changed from 0 to 0.06%(volume fraction). The enhancement effect was attributed to the increasing ·OH radical concentration and formation of chlorine-containing radicals in the presence of CCl₄ during ultrasonic processes. Levofloxacin degradation efficiency by ultrasonic in the presence of CCl₄ increased with the increasing of ultrasonic power in 100-200 W. The pH values of solution had prominent effect on levofloxacin degradation, while the initial concentration of levofloxacin had a negative effect. The temperature between 33-49 ℃ was found to be favorable to levofloxacin degradation. Moreover, HPLC analysis showed that two main by-products were simultaneously produced in the course of the ultrasonic degradation of levofloxacin in addition of CCl₄, the two products were confirmed by LC-MS/MS analysis.

Key words: Quinolone antibiotics, Levofloxacin, Ultrasonic degradation, Carbon tetrachloride