Behavior of Antimony(V) during the Transformation of Ferrihydrite and Its Environmental Implications
Behavior of Antimony(V) during the Transformation of Ferrihydrite and Its Environmental Implications
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DOI：
10.1021/es4010398
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发表时间：
2013-09-03
影响因子：
11.4
通讯作者：
Sakata, Masahiro
中科院分区：
文献类型：
--
作者：
Mitsunobu, Satoshi;Muramatsu, Chihiro;Sakata, Masahiro
在这项研究中，我们研究了在pH值为6.0时，不同Sb/Fe摩尔比的结晶不良的Fe（III）羟基氧化物（双线水铁矿）转化过程中Sb（V）的行为。XRD和Fe EXAFS分析均证实，针铁矿和赤铁矿是水铁矿在Sb（V）存在下的主要转化产物。晶化动力学表明，含Sb（V）的转化率与对照（不含Sb（V））的转化率大致相同，这表明Sb（V）的存在对转化率没有显著影响。在整个转化过程中，Sb（V）主要分配在固相中，没有观察到Sb（V）的解吸。此外，Sb EXAFS分析表明，Sb（V）在固相结构纳入结晶针铁矿和/或赤铁矿，生成的水铁矿转化。因此，Sb（V）从亚稳的水铁矿中转移到热稳定的固体中，表明Sb（V）的刚性固定。这些发现对于预测自然环境中与水铁矿伴生的Sb的长期命运具有重要意义。
In this study, we investigated the behavior of Sb(V) during the transformation of poorly crystalline Fe(III) oxyhydroxides (two-line ferrihydrite) with various Sb/Fe molar ratios at pH 6.0. Both XRD and Fe EXAFS analyses confirmed that goethite and hematite are the primary transformation products of the ferrihydrite in the presence of Sb(V). The crystallization kinetics showed that the transformation rate with Sb(V) was approximately the same as that of the control (without Sb(V)), which indicates that the presence of Sb(V) does not influence the transformation rate to a noticeable extent. Throughout the transformation, Sb(V) dominantly partitioned in the solid phase and no desorption of Sb(V) was observed. Furthermore, Sb EXAFS analyses suggested that Sb(V) in the solid phase is structurally incorporated into crystalline goethite and/or hematite, generated by the ferrihydrite transformation. Hence, Sb(V) transfers into the thermodynamically stable solids from the metastable ferrihydrite with aging, indicating a rigid immobilization of Sb(V). These findings are valuable for making predictions on the long-term fate of Sb associated with ferrihydrite in natural environments.