Abstract Nano zero valent iron (nZVI) is a promising agent for in situ remediation of contaminated groundwater and soil. However, the limited mobility of iron nanoparticles in calcareous soils may inhibit the efficiency of this technology. Aim of this study is the evaluation of the mobility of nanoiron synthesized with green tea polyphenols in porous media containing limestone by conducting columns tests. The effect of grain size of limestone particles added in columns on nanoiron suspension transport was evaluated. It was shown that the mobility of iron nanoparticles was strongly affected by the residual acidity and the aquatic iron (Fe(III)) of the nZVI suspension in contact with limestone which caused the neutralization of acidity and the precipitation of iron oxyhydroxides on limestone surface. It was shown that the interference of Fe(III) precipitation on the nZVI suspension mobility becomes more important as the size of calcite grains decreases. Namely, the total Fe content in the solids at the end of column tests, was 4.4 mg/g in the column containing the coarser CaCO3 grains (d = 3.4 mm) and increased up to 44.8 mg/g in the column with the finer grains (d = 0.22 mm), due to higher available specific surface area. The corresponding amount of retained nanoiron, nFe (0), was 0.75 and 4.6 mg/g in the columns with the coarser and finer CaCO3 grains respectively.

中文翻译：

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石灰石粒度对绿色纳米铁悬浮液流动性的影响

摘要 纳米零价铁（nZVI）是一种很有前景的污染地下水和土壤原位修复剂。然而，铁纳米颗粒在钙质土壤中的有限流动性可能会抑制该技术的效率。本研究的目的是通过柱测试评估用绿茶多酚合成的纳米铁在含有石灰石的多孔介质中的迁移率。评估了添加到柱中的石灰石颗粒的粒度对纳米铁悬浮液传输的影响。结果表明，铁纳米颗粒的流动性受到残余酸度和与石灰石接触的 nZVI 悬浮液的水生铁（Fe（III））的强烈影响，这会导致酸度中和，并在石灰石表面沉淀氢氧化铁。结果表明，随着方解石晶粒尺寸的减小，Fe(III)沉淀对 nZVI 悬浮液迁移率的干扰变得更加重要。即，柱测试结束时固体中的总 Fe 含量在含有较粗 CaCO3 颗粒（d = 3.4 mm）的柱中为 4.4 mg/g，在含有较细颗粒的柱中增加至 44.8 mg/g (d = 0.22 mm)，由于更高的可用比表面积。在具有较粗和较细 CaCO3 晶粒的柱子中，相应的纳米铁保留量 nFe (0) 分别为 0.75 和 4.6 mg/g。由于更高的可用比表面积，在具有更细颗粒 (d = 0.22 mm) 的色谱柱中为 8 mg/g。在具有较粗和较细 CaCO3 晶粒的柱子中，相应的纳米铁保留量 nFe (0) 分别为 0.75 和 4.6 mg/g。由于更高的可用比表面积，在具有更细颗粒 (d = 0.22 mm) 的色谱柱中为 8 mg/g。在具有较粗和较细 CaCO3 晶粒的柱子中，相应的纳米铁保留量 nFe (0) 分别为 0.75 和 4.6 mg/g。