Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea.
Department of Civil and Environmental Engineering, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 05029, Republic of Korea.
Chemosphere. 2019 Jan;215:626-633. doi: 10.1016/j.chemosphere.2018.10.073. Epub 2018 Oct 13.
We developed a novel solidification and stabilization process using a nanoscale zerovalent iron (NZVI)-cement system for reductive immobilization of hexavalent uranium (U(VI)) in a soil-cement matrix. The NZVI suspension without cement demonstrated high removal efficiency (100% in 2 h) and fast removal kinetics (53.7 Lmd), which surpassed those of other Fe-containing minerals (i.e., green rust, mackinawite, magnetite, and pyrite). Significant removal of aqueous U(VI) was observed in NZVI-cement slurries and minimal adsorbed U was desorbed by a bicarbonate/carbonate (CARB) solution. Surface analysis using scanning electron microscopy and X-ray photoelectron spectroscopy revealed U distributed homogeneously on the surface of the NZVI-cement and transformed considerably from U(VI) to reduced U species by coupled oxidation of Fe(0)/Fe(II) to Fe(III). Furthermore, the increase in pH and NZVI concentration, and presence of humic acid resulted in the enhanced U(VI) reduction in NZVI-cement slurries. The NZVI-cement system was tested with a soil matrix, resulting in successful immobilization of aqueous U(VI) in both batch and column experiments. Moreover, the U(VI) removed in the NZVI-cement system was not leached out by the CARB solution during long-term experiments. The results suggest an NZVI-cement system could represent a promising remediation alternative for effective and stable immobilization of U(VI) in contaminated sites.
我们开发了一种使用纳米零价铁（NZVI）-水泥系统的凝固和稳定化新工艺，用于在土壤-水泥基质中还原固定六价铀（U(VI)）。不含水泥的 NZVI 悬浮液表现出高去除效率（2 小时内达到 100%）和快速去除动力学（53.7 Lmd），超过了其他含 Fe 矿物（即绿锈、菱铁矿、磁铁矿和黄铁矿）。在 NZVI 水泥浆中观察到 U(VI)的大量去除，而用碳酸氢盐/碳酸盐（CARB）溶液很少有吸附的 U 被解吸。使用扫描电子显微镜和 X 射线光电子能谱的表面分析表明，U 均匀分布在 NZVI-水泥的表面上，并通过耦合 Fe(0)/Fe(II)到 Fe(III)的氧化，从 U(VI)转变为还原的 U 物种。此外，pH 值和 NZVI 浓度的增加以及腐殖酸的存在导致 NZVI 水泥浆中 U(VI)的还原增强。NZVI-水泥系统在土壤基质中进行了测试，结果表明在批处理和柱实验中成功地固定了水溶液中的 U(VI)。此外，在长期实验中，CARB 溶液不会将 NZVI-水泥系统中去除的 U(VI)浸出。结果表明，NZVI-水泥系统可能是一种有前途的修复替代方案，可有效且稳定地固定污染场地中的 U(VI)。
