粉煤灰增强超声/H2O2降解左氧氟沙星的实验研究

Enhancement of levofloxacin degradation in US/H_2O_2 system by addition of fly ash

研究粉煤灰对超声/H2O2体系降解左氧氟沙星的增强效果,考察了粉煤灰添加量、H2O2浓度、溶液初始pH值、左氧氟沙星初始浓度等对降解效果的影响.结果表明,与单独超声,H2O2氧化,超声/H2O2,超声/粉煤灰,粉煤灰/H2O2氧化相比,粉煤灰有效增强了超声/H2O2体系对左氧氟沙星的降解,降解反应符合一级反应动力学.粉煤灰添加量为1.5g/L,H2O2浓度为15.0mmol/L,pH=7.16,超声功率325W,左氧氟沙星初始浓度20mg/L,反应160min,左氧氟沙星的去除率达到99.12%,TOC去除率为17.37%.利用荧光探针法对不同体系产生的·OH浓度进行了分析比较,粉煤灰作为非均相催化剂,主要在于发生类Fenton反应.采用HPLC/MS/MS方法对3种反应产物进行了分析,结果表明左氧氟沙星主要是通过喹诺酮环失去-C2,哌嗪环去亚甲基化以及·OH进攻喹诺酮环发生降解.

The intensification of levofloxacin degradation in ultrasonic/H2O2/fly ash combined system was studied. The experimental parameters such as fly ash adding amount, H2O2 concentration, pH value and levofloxacin initial concentration on degradation efficiency were evaluated. The results indicated that when compared with single sonolysis, H2O2 oxidation, ultrasonic/H2O2 and fly ash/H2O2 binary systems, levofloxacin degradation was markedly promoted in ultrasonic/H2O2/fly ash ternary system. Levofloxacin degradation in ultrasonic/H2O2/fly ash system followed apparent first-order kinetics. The removal efficiency for 20mg/L levofloxacin under fly ash adding amount of 1.5g/L, H2O2 concentration of 15.0mmol/L, pH 7.16, and ultrasonic power of 325W could achieve 99.12% within 160min treatment, whereas TOC removal only attained 17.37%. Fluorescence probe analysis indicated that the combination of ultrasonic/H2O2/fly ashenhanced the heterogeneous Fenton-like reaction on fly ash surface. HPLC/MS/MS analysis revealed that three intermediates were generated, which derived from demethylation of the piperazinyl ring,the transformation of the quinolone moiety through the loss of C2 and attack of quinolone moiety by·OH.