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A novel nZVI–bentonite nanocomposite to remove trichloroethene (TCE) from solution
Chemosphere ( IF 8.8 ) Pub Date : 2021-06-07 , DOI: 10.1016/j.chemosphere.2021.131018
Andre Baldermann 1 , Stephan Kaufhold 2 , Reiner Dohrmann 3 , Claudia Baldermann 4 , Ilse Letofsky-Papst 5 , Martin Dietzel 1
Affiliation  

Nanoscale zero-valent iron (nZVI) based (nano)composites supported by clay mineral substrates are a promising technology for the in-situ remediation of groundwater and (sub)soils contaminated with chlorinated hydrocarbons, such as trichloroethene (TCE). However, the physicochemical processes and interaction mechanisms between nZVI particles, clay minerals and TCE are poorly understood, yet. We immobilized nZVI particles on a commercial bentonite substrate to prepare a novel nZVI-B nanocomposite and tested its performance for TCE removal from solution against pure nZVI in batch reactors. The nZVI-B exhibited a higher reactivity (2.2·10−3 L h−1·m−2) and efficiency (94%) for TCE removal than nZVI (2.2·10−4 L h−1·m−2; 45%). Sorption of TCE onto the clay surfaces and reductive de-chlorination in “micro-reactors” developing within the nZVI-B controlled the kinetics and the magnitude of TCE loss from solution. Contrary to pure nZVI, no signs of nZVI particle agglomeration or inactivation due to oxide shell formation were found in nZVI-B. We attribute this to the uptake of dissolved Fe species that are liberated via progressing nZVI particle corrosion by the bentonite substrate to form Fe-smectite (nontronite domains), which prevented from a deterioration of the properties and reactivity of the nZVI-B. The use of nZVI-B in permeable reactive barriers at contaminated field sites could be feasible, where a system-inherent reduction of the soil-bearing capacity has to be minimized.



中文翻译:

从溶液中去除三氯乙烯 (TCE) 的新型 nZVI-膨润土纳米复合材料

由粘土矿物基质支撑的纳米级零价铁 (nZVI) 基(纳米)复合材料是一种很有前途的技术,用于原位修复地下水和被氯化烃(如三氯乙烯(TCE)等污染的(亚)土壤)。然而,人们对 nZVI 颗粒、粘土矿物和 TCE 之间的物理化学过程和相互作用机制知之甚少。我们将 nZVI 颗粒固定在商业膨润土基材上以制备新型 nZVI-B 纳米复合材料,并在间歇反应器中测试其从溶液中去除 TCE 与纯 nZVI 的性能。所述的nZVI-B表现出更高的反应性(2.2·10 -3  L H -1 ·米-2)和TCE去除比的nZVI(2.2效率(94%)·10 -4  L H -1·m -2;45%)。TCE 在粘土表面的吸附和在 nZVI-B 内发展的“微反应器”中的还原脱氯控制了溶液中 TCE 损失的动力学和大小。与纯 nZVI 不同,在 nZVI-B 中没有发现由于形成氧化物壳而导致 nZVI 颗粒团聚或失活的迹象。我们将此归因于溶解的 Fe 物质的吸收,这些 Fe 物质通过膨润土基质进行 nZVI 颗粒腐蚀而释放,形成 Fe-蒙脱石(绿脱石域),这防止了 nZVI-B 的性能和反应性的恶化。在受污染场地的可渗透反应屏障中使用 nZVI-B 可能是可行的,其中土壤承载能力的系统固有降低必须最小化。

更新日期:2021-06-10
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