Nano-Science Center, Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark.
AECOM Environment, Madrid, Spain; GIR-QUESCAT, Departamento de Quimica Inorgánica, Universidad de Salamanca, Salamanca, Spain.
Chemosphere. 2020 Jun;249:126137. doi: 10.1016/j.chemosphere.2020.126137. Epub 2020 Feb 6.
Sulfidized nanoscale zerovalent iron (S-nZVI) is an Fe-based reactant widely studied for its potential use for groundwater remediation. S-nZVI reactivity has been widely investigated testing various contaminants in various water matrices, but studies on S-nZVI corrosion behaviour and reactivity upon exposure to complex groundwater chemistries are limited. Here, we show that anoxic aging of S-nZVI for 7 days in the absence and presence of key groundwater solutes (i.e., Cl, SO, Mg, Ca, HCO, CO, NO, or HPO) impacts Fe corrosion extent, corrosion product and reduction rates with trichloroethene (TCE). White rust was the dominant corrosion product in ultrapure water and in SO, Cl, Mg or Ca solutions; green rust and/or chukanovite formed in HCO and CO solutions; magnetite, formed in NO solutions and vivianite in HPO solutions. The aged S-nZVI materials expectedly showed lower reactivities with TCE compared to unaged S-nZVI, with reaction rates mainly controlled by ion concentration, Fe corrosion extent, type(s) of corrosion product, and solution pH. Comparison of these results to observations in two types of groundwaters, one from a carbonate-rich aquifer and one from a marine intruded aquifer, showed that S-nZVI corrosion products are likely controlled by the dominant GW solutes, while reactivity with TCE is generally lower than expected, due to the multitude of ion effects. Overall, these results highlight that S-nZVI corrosion behaviour in GW can be manifold, with varied impact on its reactivity. Thus, testing of S-nZVI stability and reactivity under expected field conditions is key to understand its longevity in remediation applications.
硫化纳米零价铁（S-nZVI）是一种基于铁的反应剂，因其在地下水修复方面的潜在应用而被广泛研究。S-nZVI 的反应性已在各种水基质中测试各种污染物得到广泛研究，但在复杂地下水化学条件下暴露时，对 S-nZVI 腐蚀行为和反应性的研究有限。在这里，我们表明，在缺氧条件下将 S-nZVI 老化 7 天，无论是在不存在还是存在关键地下水溶质（即 Cl、SO、Mg、Ca、HCO、CO、NO 或 HPO）的情况下，都会影响 Fe 腐蚀程度、腐蚀产物和三氯乙烯（TCE）的还原速率。在超纯水中以及在 SO、Cl、Mg 或 Ca 溶液中，白色锈是主要的腐蚀产物；在 HCO 和 CO 溶液中形成绿锈和/或水铁矿；在 NO 溶液中形成磁铁矿，在 HPO 溶液中形成磷铁矿。与未老化的 S-nZVI 相比，老化的 S-nZVI 材料对 TCE 的反应性明显较低，反应速率主要受离子浓度、Fe 腐蚀程度、腐蚀产物类型和溶液 pH 控制。将这些结果与两种地下水（一种来自富含碳酸盐的含水层，一种来自受海水入侵的含水层）的观察结果进行比较表明，S-nZVI 腐蚀产物可能受主要 GW 溶质控制，而与 TCE 的反应性通常低于预期，这是由于多种离子效应的影响。总的来说，这些结果强调了 S-nZVI 在 GW 中的腐蚀行为可能多种多样，对其反应性的影响也各不相同。因此，在预期的现场条件下测试 S-nZVI 的稳定性和反应性对于了解其在修复应用中的寿命至关重要。
