The nano-zero-valent iron composite (nZVI@TP-Mont) was successfully prepared using a low-cost and environmental-friendly green synthesis via tea leaves extract (tea polyphenols, TPs) and the montmorillonite (Mont). The batch and column experiments and characterization were conducted to investigate the transport behavior and Cr(VI) remediation by nZVI@TP-Mont in water/soil. Due to its particular surface characteristics and morphology (i.e., the Fe⁰ core wrapped by TPs, the doped sulfur, and interlayer structure), the nZVI@TP-Mont composite showed a great removal capacity of Cr(VI) and sufficient mobility under different soil conditions. We opine the increase in the Cr(VI) reduction of nZVI@TP-Mont was attributed to the tethering of Fe₂O₃ on the surface of Fe⁰ core by the support of Mont interlayer, especially the TP-coverage around nZVI@TP-Mont surface unwrapped, thereby increasing the regenerated reactive Fe²⁺ and the exposed reaction sites of Fe⁰ cores to Cr(VI). The increased transportability of nZVI@TP-Mont slightly depends on the heterogeneous soil properties (i.e., ionic strength, sand/soil ratio, and pH). The two-site kinetic attachment model fitting results suggest Cr(VI)/Cr(III) speciation associated with the agglomerated nZVI@TP-Mont were efficiently immobilized in soil. Therefore, this study would benefit the efficient application of the green-synthesized nZVI@TP-Mont in in-situ remediation of soils contaminated by Cr(VI).

以茶叶提取物（茶多酚，TPs）和蒙脱石（Mont）为原料，采用低成本、环保的绿色合成方法成功制备了纳米零价铁复合材料（nZVI@TP-Mont）。进行批量和柱状实验和表征以研究 nZVI@TP-Mont 在水/土壤中的迁移行为和 Cr(VI) 修复。由于其特殊的表面特征和形貌（即由 TPs 包裹的 Fe ⁰核、掺杂的硫和层间结构），nZVI@TP-Mont 复合材料在不同的土壤条件。我们认为 nZVI@TP-Mont 的 Cr(VI) 还原增加归因于 Fe ₂ O ₃在 Fe 表面的束缚⁰核通过Mont夹层的支撑，尤其是nZVI@TP-Mont表面周围的TP覆盖层展开，从而增加了再生反应性Fe ²⁺和Fe ⁰核暴露于Cr(VI)的反应位点。nZVI@TP-Mont 增加的可运输性略微取决于异质土壤特性（即离子强度、沙土比和 pH 值）。双位点动力学附着模型拟合结果表明，与凝聚的 nZVI@TP-Mont 相关的 Cr(VI)/Cr(III) 形态被有效地固定在土壤中。因此，本研究将有利于绿色合成的 nZVI@TP-Mont 在原位修复被 Cr(VI) 污染的土壤中的有效应用。