A novel three-dimensional electrokinetic remediation (3D EKR) system, with FeO_x/granular activated carbon (GAC) composite constituting a third electrode was investigated for the removal of Cr from a real contaminated soil. Such third electrode particles were distributed evenly throughout the contaminated soil and their additional presence enabled the generation of a higher and more stable current density and reduced acid-base polarization of the soil, when compared against a conventional 2D EKR (cathode-anode) system. This resulted in a higher Cr removal, which was primarily driven by enhanced oxidation of Cr(III) to more mobile Cr(VI) aqueous complexes, which electromigrated towards the anode and into the anolyte. Analysis of FeO_x/GAC and soil samples before and after EKR using XRD, FTIR, SEM-EDS, and XPS confirmed that: (i) both oxidation of Cr(III) and reduction of Cr(VI) occurred simultaneously on particle electrode surfaces; and (ii) aqueous Cr transport governed by electromigration was enhanced by Electro-Fenton reactions and hydrolysis on FeO_x/GAC. A further benefit of 3D EKR was the promotion of residual Cr(III), in proximity to the cathode, to barely soluble crystalline silicate phases, therefore further decreasing the overall toxicity of the soil. This study therefore provides a highly promising first insight into the use of 3D EKR for the removal of Cr from contaminated land. Future work will seek to examine this emerging new technology at large scale and for different contaminated land scenarios, therefore further developing it towards a potential commercial application.

研究了一种新型三维电动修复 (3D EKR) 系统，其中 FeO _x /颗粒活性炭 (GAC) 复合材料构成第三电极，用于从真实污染土壤中去除 Cr。与传统的 2D EKR（阴极 - 阳极）系统相比，这种第三电极颗粒均匀分布在整个受污染的土壤中，并且它们的额外存在能够产生更高和更稳定的电流密度并减少土壤的酸碱极化。这导致更高的 Cr 去除率，这主要是由 Cr(III) 增强氧化成更具流动性的 Cr(VI) 水性络合物驱动的，后者向阳极电迁移并进入阳极电解液。FeO _x的分析/GAC 和 EKR 前后的土壤样品使用 XRD、FTIR、SEM-EDS 和 XPS 证实：(i) Cr(III) 的氧化和 Cr(VI) 的还原同时发生在颗粒电极表面；_{(ii) 电迁移控制的水性 Cr 传输通过 FeO x}上的电芬顿反应和水解得到增强/广汽集团。3D EKR 的另一个好处是促进阴极附近残留的 Cr(III) 变成几乎不溶的结晶硅酸盐相，因此进一步降低了土壤的整体毒性。因此，这项研究为使用 3D EKR 从污染土地中去除 Cr 提供了一个非常有前途的初步见解。未来的工作将寻求大规模和针对不同的污染土地场景检查这种新兴技术，从而进一步将其开发为潜在的商业应用。