超声/过硫酸盐联合降解1,1,1-三氯乙烷的机理研究  

On the mechanism of 1,1,1-trichloroethane degradation by simultaneous application of ultrasound and persulfate

作　　者：李炳智[1] 

机构地区：[1]上海市环境科学研究院,上海200233

出　　处：《安全与环境学报》2013年第4期29-36,共8页Journal of Safety and Environment

基　　金：上海市环保局重大科研项目(沪环科2012-07);上海市自然科学基金面上项目(12ZR1426500;13ZR1435200)

摘　　要：以地下水中典型氯代烃1,1,1-三氯乙烷(TCA)为目标污染物,研究了其在超声/过硫酸盐联合体系中的降解动力学和机理。结果表明,超声/过硫酸盐联合体系具有显著的协同效应,体系TCA降解速率比单独超声和单独过硫酸盐体系降解速率之和提高9.61倍,其表观拟一级反应动力学速率常数随超声频率的增加而增大,随过硫酸盐与TCA物质的量比以及无机阴离子(HCO3-、CO23-、Cl-和NO3-)质量浓度的增大而减小。TCA可被联合体系完全降解,SO4-.和.OH在其降解过程中发挥了重要作用。结合吹扫捕集-气质联用(P&T-GC-MS)分析,给出了TCA可能的降解途径,并对联合体系处理某氯代烃污染场地地下水的性能进行了测试。The present paper intends to make an investigation of the kinetic degradation mechanism of 1,1,1-trichloroethane（TCA）,one of the prevalent chlorinated hydrocarbons present in the contaminated groundwater.The experimental results indicate that TCA degradation rate by ultrasonic/persulfate system tends to increase significantly 9.61 times as high as the total degradation rate of the single ultrasound and the single persulfate systems,which suggests quite obvious synergic effect.Our investigation also proves that the pseudo-first-order rate constants tends to increase with the increase of ultrasonic frequency from 50 kHz to 400 kHz but decrease both with the increase of PS/TCA molar ratio from 10：1 to 100：1 and the increase of concentration of inorganic anions（Cl-,HCO-3,CO2-3,and NO-3） in the range of 0-3.6 mg/L,0-6.1 mg/L,0-6.0 mg/L and 0-6.2 mg/L,respectively.What is more important,it is possible for TCA to be eliminated completely by ultrasound/persulfate system under the optimal conditions when the initial pH is 7.0,the ultrasonic frequency is 400 kHz with the power of 100 W,T=（20±2） ℃ and n（PS）/n（TCA）=10：1,respectively,and with the sulfate and hydroxyl radicals serving as the key oxidants.The radicals can be verified by the experiments of addition of radical scavengers（methanol and tert-butyl alcohol） to the pollutant.Based on our experiment results,the present author have also proposed a tentative pathway of TCA degradation through the mass spectrometry（PT-GC-MS） analysis in combination with the twelve types of chlorinated intermediates,which can be identified by the purge and trap gas chromatography.Its degradation proves to follow either the thermal decomposition or a free radical-induced reaction mechanism.The treatability exploration of the contaminated groundwater from the certain contamination site by this process shows that it is possible to attain the complete removal of TCA（25 mg/L） for 150 min by this method.What is more meaningful,the coupling of ultrasound a

关 键 词：环境工程学 超声 过硫酸盐 1 1 1-三氯乙烷 动力学 机理 

分 类 号：X703.1[环境科学与工程—环境工程]