The contamination by chlorinated organic solvents is a worldwide problem as they can deeply penetrate aquifers, accumulating in the sub-surface as lenses of highly hazardous pollutants. In recent years, so called in situ oxidation processes have been developed to remediate chlorinated organic solvents from groundwater and soil by injecting solutions of oxidising agents such as permanganate or peroxydisulphate. We here present modified layered double hydroxides (LDHs) with intercalated oxidising agents that might serve as new reactants for these remediation strategies. LDHs might serve as support and stabiliser materials for selected oxidising agents during injection, as the uncontrolled reaction and consumption might be inhibited, and guarantee that the selected oxidants persist in the subsurface after injection. In this study, LDHs with hydrotalcite- and hydrocalumite-like structures intercalated with permanganate and peroxydisulphate anions were synthesised and their efficiency was tested in batch experiments using trichloroethene or 1,1,2-trichloroethane as the target contaminants. All samples were characterised using powder X-ray diffraction, thermal analysis coupled with mass spectrometry to directly analyse evolving gases, and Fourier-transform infrared spectroscopy. Additionally, particle size distribution measurements were carried out on the synthesised materials. Results of the batch experiments confirmed the hypothesis that oxidising agents keep their properties after intercalation. Permanganate intercalated LDHs proved to be most efficient at degrading trichloroethene while peroxydisulphate intercalated Ca,Al-LDHs were the most promising studied reactants degrading 1,1,2-trichloroethane. The detection of dichloroethene as well as the transformation of the studied reactants into new LDH phases confirmed the successful degradation of the target contaminant by oxidation processes generated from the intercalated oxidising agent.

中文翻译：

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层状双氢氧化物与高锰酸根和过二硫酸根离子的夹层，用于氧化去除氯化有机溶剂污染的水

氯化有机溶剂的污染是一个世界性的问题，因为它们可以深深地渗透到含水层中，作为高度危险的污染物的透镜在地下积聚。近年来，通过注入氧化剂（如高锰酸盐或过氧二硫酸盐）溶液，开发了所谓的原位氧化方法，以修复地下水和土壤中的氯化有机溶剂。我们在这里介绍了带有插层氧化剂的改性层状双氢氧化物（LDHs），它们可以用作这些修复策略的新反应物。LDHs可能会在注射过程中用作选定氧化剂的载体和稳定剂，因为可能会抑制不受控制的反应和消耗，并确保选定的氧化剂在注射后仍然存在于地下。在这个研究中，合成了具有高锰酸根和过氧二硫酸根阴离子嵌入的水滑石和类水铝钙石结构的LDH，并使用三氯乙烯或1,1,2-三氯乙烷作为目标污染物，通过分批实验测试了它们的效率。所有样品的特征均使用粉末X射线衍射，热分析与质谱联用以直接分析不断散发的气体以及傅立叶变换红外光谱进行表征。另外，对合成材料进行粒度分布测量。批处理实验的结果证实了这样的假设：氧化剂在插层后仍保持其性能。事实证明，高锰酸盐插层的LDH能够最有效地降解三氯乙烯，而过氧二硫酸盐插层的Ca，Al-LDHs是最有前途的研究对象，可降解1,1,2-三氯乙烷。对二氯乙烯的检测以及研究的反应物向新的LDH相的转化证实了嵌入的氧化剂产生的氧化过程能够成功降解目标污染物。