In this study, thermally activated persulfate (PS) to stimulate the oxidation of 1,1,1-trichloroethane (TCA) in groundwater remediation was investigated. The effects of various factors including temperature; initial TCA concentration; PS/TCA molar ratio; solution pH; and common constituents in groundwater such as Cl^–, HCO₃^–, SO₄^2–, and NO₃^– anions and humic acid (HA) were evaluated. The experimental results showed that TCA can be completely oxidized in 2 h at 50 °C with a PS/TCA molar ratio of 100/1, indicating the effectiveness of thermally activated PS oxidation for TCA removal. TCA oxidation was fitted with a pseudo-first-order kinetic model, and the rate constant was found to increase with increasing temperature and PS/TCA molar ratio, but to decrease with increasing initial TCA concentration. In addition, acidic conditions were favorable to TCA removal and elevating, the initial solution pH value (from pH 3 to 11) decreased the TCA degradation rate. Anions Cl^– and HCO₃^– had negative effects on TCA removal, whereas the effects of both SO₄^2– and NO₃^– were negligible. With 5–10 mg L^–1 concentrations of HA in solution, an inhibitive effect was observed, indicating that dissolved organic matter consumed some of the oxidant. However, the anticipated effective thermally activated PS oxidation of TCA in groundwater from a real contaminated site was not achieved because of the complex solution matrix. On the other hand, the TCA degradation mechanism derived from GC/MS analytical results confirmed formic acid, dichloromethane, and trichloromethane as the primary intermediates, and therefore, two TCA decomposition pathways were proposed. In conclusion, thermally activated PS oxidation is a highly promising technique for TCA-contaminated groundwater remediation, but more complex constituents in in situ groundwater should be carefully considered for its practical application.

中文翻译：

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热活化过硫酸盐刺激的1,1,1-三氯乙烷的氧化

在这项研究中，研究了热活化过硫酸盐（PS）刺激地下水修复过程中1,1,1-三氯乙烷（TCA）的氧化。温度等各种因素的影响；TCA初始浓度；PS / TCA摩尔比；溶液pH值 以及地下水中的常见成分，例如Cl ^–，HCO ₃ ^–，SO ₄ ^2–和NO ₃ ^–评估了阴离子和腐殖酸（HA）。实验结果表明，TCA可以在50°C下2 h内被PS / TCA摩尔比为100/1完全氧化，表明热活化PS氧化对于TCA去除的有效性。TCA氧化符合拟一级动力学模型，发现速率常数随温度和PS / TCA摩尔比的增加而增加，但随初始TCA浓度的增加而降低。此外，酸性条件有利于TCA的去除和升高，初始溶液的pH值（从3至11）降低了TCA的降解速率。阴离子Cl ^–和HCO ₃ ^–对TCA的去除有负面影响，而SO ₄ ^2–和NO _3的影响^–可以忽略不计。含5–10 mg L ^–1在溶液中高浓度的HA时，观察到了抑制作用，表明溶解的有机物消耗了一些氧化剂。然而，由于复杂的溶液基质，未能实现预期的来自实际污染地点的地下水中TCA的有效热活化PS氧化TCA的效果。另一方面，从GC / MS分析结果得出的TCA降解机理证实了甲酸，二氯甲烷和三氯甲烷为主要中间体，因此提出了两种TCA分解途径。总之，热活化的PS氧化技术是用于TCA污染的地下水修复的非常有前途的技术，但是在实际应用中应仔细考虑原位地下水中更复杂的成分。