Intensification of sonochemical degradation of antibiotics levofloxacin using carbon tetrachloride

Sonochemical degradation of levofloxacin was investigated to assess the operational parameters and the impacts of rate enhancers (CCl4) and rate inhibitors (t-butanol). Different dosages of CCl4, pH value of solutions, ultrasonic power, and initial concentration of levofloxacin which affected the degradation of levofloxacin were studied. The degradation rate of levofloxacin was accelerated with increased concentrations of CCl4 via the accumulation of reactive chlorine species and the hindrance of OH radical combination reactions with atomic hydrogen. The addition of t-butanol at all test concentrations inhibited the degradation of levofloxacin regardless of the quantity of OH radicals in solution. It was also found that 5-day biochemical oxygen demand (BOD5) of the solution increased evidently after sonochemical treatment, and the ratio of BOD5/COD that was a good measure for biodegradability increased from 0 to 0.41, which indicated that biodegradability of the solution was obviously enhanced. Based on the results, it is feasible that sonochemical oxidation can be used for pretreatment of levofloxacin effluent before biological treatment processes.