Toxic metal contamination in soils is a major problem that poses risk to public health and the environment. Among the metal contaminants, hexavalent chromium (Cr(VI)) is known to be highly toxic and mobile in the soils, creating major environmental liabilities around the world. This study evaluates the efficiency of applying the pressure injected nanoscale zero-valent iron (nZVI) suspension to remediate Cr(VI)-contaminated clay soil. After nZVI injection, soil samples were collected in different depths, radial distances, and time intervals. The nZVI dosage used was 12.5 g/kg. The effect of nZVI on Cr(VI) reduction was observed at all radial and depth locations analyzed, with an initial reduction of up to 51.08% for the deepest layer. nZVI dispersivity was found to be homogeneous in the analyzed sample, with an average Cr(VI) reduction of 76.52% in 15 days. The nZVI migration patterns had an influence on the experimental results, with Cr(VI) reduction up to 56.92% higher at deeper points of the experiment. Moisture content was a key parameter for the effectiveness of the remediation and its control was necessary. Overall, the application of nZVI by the pressure injection technique was found to be an effective alternative for the remediation of Cr(VI)-contaminated clay soil.

Graphical abstract

中文翻译：

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纳米零价铁（nZVI）注射修复六价铬污染粘土

土壤中的有毒金属污染是一个对公众健康和环境构成风险的主要问题。在金属污染物中，众所周知，六价铬 (Cr(VI)) 具有剧毒且可在土壤中流动，在世界范围内造成了重大的环境责任。本研究评估了应用压力注入纳米级零价铁 (nZVI) 悬浮液修复受 Cr(VI) 污染的粘土的效率。注入 nZVI 后，以不同深度、径向距离和时间间隔收集土壤样品。使用的 nZVI 剂量为 12.5 g/kg。在分析的所有径向和深度位置观察到 nZVI 对 Cr(VI) 还原的影响，最深层的初始还原高达 51.08%。在分析的样品中发现 nZVI 分散性是均匀的，平均 Cr(VI) 减少了 76。15 天内 52%。nZVI 迁移模式对实验结果有影响，在实验的较深点，Cr(VI) 减少高达 56.92%。水分含量是影响修复效果的关键参数，必须对其进行控制。总体而言，发现通过压力注入技术应用 nZVI 是修复 Cr(VI) 污染粘土的有效替代方法。

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