超声/K_2S_2O_8体系降解水中左旋氧氟沙星的研究

Degradation of levofloxacin in aqueous solution using US/K_2S_2O_8

【目的】研究超声/K2S2O8体系对水中抗生素左旋氧氟沙星的降解效果。【方法】利用超声波粉碎装置,采用HPLC分析法,考察了反应条件、K2S2O8添加质量浓度、溶液初始pH值、左旋氧氟沙星初始质量浓度对水中左旋氧氟沙星降解率的影响,并分析了左旋氧氟沙星降解过程中总有机碳(TOC)去除率及HPLC图谱的变化。【结果】与单独超声和K2S2O8氧化相比,超声/K2S2O8对水中左旋氧氟沙星具有明显的降解效果,这主要是因为体系中硫酸根自由基(SO-·4)的氧化作用所致。K2S2O8添加质量浓度在1.0~4.0g/L时,左旋氧氟沙星的降解率随其添加质量浓度的增大而提高;超声/K2S2O8降解水中左旋氧氟沙星时,体系pH在未调节(pH=7.14)条件下效果最佳;左旋氧氟沙星初始质量浓度在10~30mg/L时,左旋氧氟沙星的降解率随其初始质量浓度的增加先升高后降低。超声/K2S2O8对左旋氧氟沙星的矿化效果也非常明显,在超声功率为195 W、pH=7.14、左旋氧氟沙星初始质量浓度为20mg/L、K2S2O8添加质量浓度为4.0g/L条件下反应240min时,左旋氧氟沙星TOC的去除率达到56.78%。HPLC分析发现,超声/K2S2O8体系降解左旋氧氟沙星的过程中有3种中间产物生成。【结论】超声/K2S2O8体系可有效降解水中的左旋氧氟沙星。

【Objective】Combined ultrasonic/K2S2O8 system was used to degrade levofloxacin in aqueous solution.【Method】Ultrasonic grinding device and HPLC were used to study the effects of reaction conditons,K2S2O8 concentration,initial pH value and levofloxacin initial concentration on levofloxacin degradation.The removal of TOC and change in HPLC spectrum during levofloxacin degradation were analyzed as well.【Result】Compared to independent ultrasonic or K2S2O8 oxidation,combined ultrasonic/K2S2O8 system had synergetic effect on degrading levofloxacin due to the oxidation ability of sulfate radicals(SO-·4).The degradation rate of levofloxacin increased with K2S2O8 concentration in the range of 1.0to4.0g/L while the degradation rate decreased after initial increase when the initial concentration was in the range of 10-30 mg/L.Unchanged pH(7.14)had the best levofloxacin degradation rate.Ultrasonic/K2S2O8 system was also very effective for mineralization of levofloxacin.The TOC removal efficiency of 20mg/L levofloxacin with ultrasound power of 195 W,pH of 7.14,and K2S2O8 concentration of 4.0g/L in240 min was 56.78%.Three products were identified during levofloxacin oxidation by HPLC.【Conclusion】Combined ultrasonic/K2S2O8 system can effectively degrade levofloxacin in aqueous solution.