| 英文摘要 |
Two oxidants, persulfate and permanganate, were employed to explore the performance of in-situ chemical oxidation (ISCO) of chlorinated solvent in an artificial aquifer. To evaluate the effectiveness of the oxidants of destroying TCE contaminant in an artificial aquifer, the batch-scale experiment was first conducted in this project. The kinetics of heat-assisted persulfate and permanganate oxidation of trichloroethylene (TCE) in aqueous solutions at various oxidant concentrations, ionic strength and anionic species was studied. It is found that the systems with buffered solution have a nearly constant pH value during the experimental period. A higher oxidant/TCE molar ratio in the oxidation experiments resulted higher efficiencies of TCE destruction by persulfate and permanganate. The presence of organic compounds (methanol in this case) may significantly slow the oxidation kinetics of TCE by persulfate. The TCE oxidation kinetics was also influence by the presence of three anions, nitrate, chloride, and bromide, at different extent. For nitrate, the influence is the smallest and may be attributed to the effect of increasing ionic strength. For both chloride and bromide, in addition to the ionic strength effect, it is speculated that the two anions were radical scavengers that caused additional reduction of reaction rates. In addition, the effect is more substantial for permanganate that persulfate. The formation of small particles during permanganate oxidation was monitored in both batch and sand-box experiments. At the same permanganate concentration, larger particles formed at higher TCE concentration in the batch experiments. This is also observed in the sand-box experiments, in which only very small amount of precipitates were observed, perhaps due to low TCE concentration in the system. After analyzed by XRD, the precipitates were mainly potassium permanganate and MnO2. In addition, the flow pattern of tracer and oxidants were similar, suggesting that the tracer may be used to simulate the flow of the oxidants in the sand box system.
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