热活化过硫酸钠处理水溶液及泥浆系统中1,1,1-三氯乙烷的研究

研究了热活化过硫酸钠技术氧化水溶液及泥浆系统中1,1,1-三氯乙烷(1,1,1-trichloroethane,TCA)的效果.考察了温度、溶液pH值、氯离子及碳酸氢根离子对水溶液中TCA降解过程的影响,并处理了实际TCA污染地下水.结果表明:TCA氧化降解过程符合准一级动力学反应方程,且温度越高TCA降解速率越大,50°C、过硫酸钠/TCA物质的量比=100/1时,TCA在2h内可完全降解;溶液pH值越高TCA去除效率越低,且碱性条件明显地抑制TCA降解;氯离子及碳酸氢根离子均会对反应起到抑制作用,其中碳酸氢根抑制作用强于氯离子;由于实际地下水水质较为复杂,TCA降解速率相对缓慢,7d后去除率达到90%以上.泥浆系统中TCA降解效率受土壤有机质含量影响较大,土壤去除有机质后降解速率明显加快.热活化过硫酸钠技术用于修复TCA污染地下水具有较大潜力,但实际应用过程中应充分考虑场地性质的影响.

Oxidation of 1,1,1-trichloroethane in aqueous and slurry systems by thermally activated persulfate

Thermally activated persulfate oxidation of 1,1,1-trichloroethane(TCA) was investigated in aqueous and slurry systems.The effects of various factors were investigated in the aqueous system,including temperature,solution pH and Cl-and HCO-3 anions.The oxidation performance on real TCA contaminated groundwater was also evaluated.The results showed that TCA oxidation fitted to a pseudo-first-order kinetic model,and the rate constant increased with increasing temperature.Complete oxidation of TCA could be achieved in 2 h with a persulfate/TCA molar ratio of 100/1 at 50 ℃.TCA oxidation rate decreased with increasing solution pH,and a significant inhibition effect was observed in the base condition.Both Cl-and HCO-3 anions had scavenging effects on TCA oxidation performance,especially for HCO-3 anion.Over 90% of TCA in the real contaminated groundwater could be oxidized after 7 d due to the complex solution matrix.In soil slurry system,the organic matters exhibited significant competition for persulfate,and TCA oxidation efficiency increased significantly when the organic matters were previously removed.This suggested that organic matters also consumed some reactive species.In conclusion,thermally activated persulfate oxidation had great potential for TCA-contaminated groundwater remediation.However,more complex constituents in in-situ groundwater should be carefully considered in its practical implementation.