Abstract Despite decades-long research efforts, the remediation of groundwater contaminated by heavy metals has remained a significant challenge. Recent studies have demonstrated that in situ formation of magnetite might be an effective method to more permanently immobilize metal(loid)s. However, how the co-existence of additional heavy metals affects the synthesis of magnetite under environmentally relevant conditions and how it affects the associated heavy metal removal efficiency have remained unclear. Here, a common magnetite synthesis procedure was used to synthesize Cu-, Cd-, and Pb-substituted magnetites at circumneutral pH with variable heavy metal concentrations. The synthesized mineral products were then subjected to digestion, Mossbauer, XRD, SEM-EDS, magnetic susceptibility and surface area measurements, as well as isothermal adsorption experiments. The presence of additional divalent heavy metals during synthesis affected the characteristics of the Fe mineral products. Magnetite formed in the presence of heavy metals was poorly crystalline and impure. The mineralogy and morphology of the products was regulated by the surface affinity of the heavy metal. The co-existence of divalent heavy metal cations that have higher surface affinity than Fe(II) suppressed the mineral growth of more crystalline Fe oxides, including magnetite. Minerals synthesized in the absence of heavy metals had higher capacity and affinity for heavy metals than minerals synthesized in the presence of those metals because of the effects of altered mineral surface structure and surface area on adsorption. These results help us understand how different types and concentrations of heavy metals affect magnetite synthesis and its suitability for in situ groundwater remediation.

中文翻译：

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二价重金属阳离子对磁铁矿合成及特性的影响

摘要 尽管经过数十年的研究努力，重金属污染地下水的修复仍然是一项重大挑战。最近的研究表明，原位形成磁铁矿可能是一种更永久地固定金属（液体）的有效方法。然而，在环境相关条件下，额外重金属的共存如何影响磁铁矿的合成以及它如何影响相关的重金属去除效率仍不清楚。在这里，一个常见的磁铁矿合成程序被用来合成铜、镉和铅取代的磁铁矿，在周围中性 pH 值下具有可变的重金属浓度。然后对合成的矿物产品进行消化、穆斯堡尔、XRD、SEM-EDS、磁化率和表面积测量，以及等温吸附实验。合成过程中额外二价重金属的存在影响了铁矿物产品的特性。在重金属存在下形成的磁铁矿结晶性差且不纯。产物的矿物学和形态受重金属的表面亲和力调节。具有比 Fe(II) 更高表面亲和力的二价重金属阳离子的共存抑制了更多结晶 Fe 氧化物（包括磁铁矿）的矿物生长。由于改变的矿物表面结构和表面积对吸附的影响，在没有重金属的情况下合成的矿物比在这些金属存在下合成的矿物具有更高的吸附能力和亲和力。