Influence of Fe(II) on the Se(IV) sorption under oxic/anoxic conditions using bentonite.
Influence of Fe(II) on the Se(IV) sorption under oxic/anoxic conditions using bentonite.
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DOI：
10.1016/j.chemosphere.2017.10.143
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发表时间：
2018-02
期刊：
影响因子：
8.8
通讯作者：
Jiangang He;Yanlin Shi;Xiaoyu Yang;Wanqiang Zhou;Yao Li;Chunli Liu
中科院分区：
文献类型：
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作者：
Jiangang He;Yanlin Shi;Xiaoyu Yang;Wanqiang Zhou;Yao Li;Chunli Liu
硒是核废料处理的关键放射性核素之一，威胁着环境质量和人类健康。因此，它需要与生物圈永久隔离。研究了pH为2.0 ~ 10.0的膨润土在氧/缺氧条件下，Fe(II)/Fe（III）对其除硒效果的影响。在氧气条件下，Se（IV）倾向于与Fe(III)-氢氧化物形成球内配合物，这是由Fe（II）使用氧气氧化而产生的。有趣的是，Se（IV）会与Fe（III）相互作用，在pH ~ 4的氧化条件下形成难溶的亚硒酸铁。在缺氧条件下，Fe（II）的浓度与Se（IV）在膨润土上的吸附过程密切相关。当Fe（II）浓度小于1%时，Fe（II）与羟基结合形成Fe(OH)2，在pH ~ 8时发生歧化反应，形成新的吸附剂Fe3O4。当Fe（II）浓度增加到5%时，还原沉淀是去除水溶液中Se（IV）的主要方式。XANES （x射线吸收近边结构）光谱表明，较高的pH值有利于形成最终的热力学还原产物硒化铁。结果表明，Fe（II）对Se（IV）的吸附有显著影响。综上所述，本研究证实了Fe（II）对79se的阻滞作用和对水圈中Se（IV）污染的修复作用。
79Se, one of the key radionuclides for nuclear waste disposal, threatens the quality of the environment, as well as human health. Therefore, it needs to be permanently isolated from the biosphere. The aim of the study was to investigate the effects of Fe(II)/Fe(III) on the removal of79Se using bentonite in the pH range of 2.0–10.0 under oxic/anoxic conditions. Under oxic conditions, Se(IV) prefers to form inner-sphere complexes with Fe(III)-oxyhydroxide, derived from the oxidization of Fe(II) using oxygen. Interestingly, Se(IV) will interact with Fe(III) and form a poorly soluble ferric selenite at pH ∼4 under oxic conditions. Under anoxic conditions, however, the concentration of Fe(II) is closely related to the sorption process of Se(IV) on bentonite. When the concentration of Fe(II) was less than 1%, Fe(II) combined with the hydroxyl, forming Fe(OH)2, which generated a disproportionation at pH ∼8 and formed a new sorbent, Fe3O4. However, when the concentration of Fe(II) was increased to 5%, reduction precipitation was the primary way to remove Se(IV) in aqueous solution. XANES (X-ray Absorption Near Edge Structure) spectra showed that higher pH values are beneficial for the formation of the final thermodynamic reduction product, Fe selenide. These results suggested that Fe(II) significantly affect the Se(IV) sorption. Overall, this study confirmed the significant role of Fe(II) on the retardation of79Se and on remediation for Se(IV) contamination in the hydrosphere.