Degradation of Trichloroethylene in Solutions Containing Tween-80 by Enhanced Sodium Persulfate
Trichloroethylene(TCE)degradation in aqueous solution containing Tween-80(TW-80)was carried out using iron scraps(IS)coupled with citric acid(CA)to enhance Fe(Ⅱ)-activated sodium persulfate(PS)system.The effects of IS synergized with CA on the enhancement of PS/Fe(Ⅱ)system were explored,and the influences of chemical dosage,TW-80 concentration,initial solution pH,and inorganic anions on TCE degradation(with TW-80)were investigated.The main reactive oxygen species responsible for TCE degradation were confirmed.The results showed that IS synergized with CA can effectively enhance the TCE removal,and when the initial concentrations of TCE and TW-80 were 0.15 mmol/L and 1.0 g/L,respectively,TCE degradation reached 92.4％with the dosages of 4.5 mmol/L,0.6 mmol/L,and 2.5 g/L of PS,Fe(Ⅱ)-CA,and IS,respectively.The presence of TW-80 inhibited the TCE degradation,and the higher its concentration,the stronger the inhibition.Free radical scavenging tests and electron paramagnetic resonance analysis showed that both HO·and SO4-·played important roles in TCE degradation with SO4-·more important than HO·.In PS/Fe(Ⅱ)/CA/IS system,a desired TCE removal performance was obtained at the initial solution pH＜9.The presence of Cl-in the solution did not have a significant effect on TCE degradation,while the inhibition caused by HCO3-was obvious.TCE removal was inhibited in the simulated actual groundwater experiment due to the complex solution matriexs,and the adverse effect can be overcome by increasing the chemical dosage,thus achieving higher TCE removal efficiency.
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