The influence of pH and reaction time on the formation of FeSe2 upon selenite reduction by nano-sized pyrite-greigite
The influence of pH and reaction time on the formation of FeSe2 upon selenite reduction by nano-sized pyrite-greigite
复制标题
pH和反应时间对纳米黄铁矿-灰云母还原亚硒酸盐生成FeSe2的影响
DOI：
10.1515/ract-2015-2496
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发表时间：
2016-09-01
影响因子：
1.8
通讯作者：
Yang, Yongqiang
中科院分区：
文献类型：
--
作者：
Kang, Mingliang;Bardelli, Fabrizio;Yang, Yongqiang
摘要研究了pH值和反应时间对纳米级硫铁矿-硫砷铁矿还原沉淀Se（IV）生成FeSe 2的影响。79 Se是一种危险的放射性同位素，在高放废物地质处置中，还原沉淀是降低其迁移率的有效方法。结果表明，在pH <4.05时，Se（0）生成，而在pH > 6.07时，Se（0）与FeSe 2形成沿着大量的FeSe 2。这些观察结果与本工作中报道的热力学预测一致。此外，发现FeSe 2的形成通过增加反应时间而继续，表明在反应早期阶段中形成的Se（0）在Se（IV）水溶液耗尽时逐渐转化为FeSe 2。由于FeSe 2具有比黄铁矿更强的反应性，因此提出了负责形成FeSe 2的是云英岩，而不是黄铁矿。在这项研究中的发现是感兴趣的关键地球化学过程中的流动性有毒的79硒在环境中存在的铁硫化物。
Abstract The influence of pH and reaction time on the formation of FeSe2 by reductive precipitation of Se(IV) with nano-sized pyrite-greigite was investigated. Reductive precipitation is an effective method of attenuating the mobility of 79Se, which is foreseen to be a dangerous radioisotope for the geological disposal of high-level radioactive waste (HLW). The results indicated that Se(0)was formed at pH <4.05, whereas, at pH > 6.07, considerable amount of FeSe2 was formed along with Se(0). These observations are in agreement with the thermodynamic predictions reported in this work. Furthermore, the formation of FeSe2 was found to continue by increasing the reaction time, indicating that the Se(0) formed in the early reaction stage is gradually transformed to FeSe2 upon the depletion of aqueous Se(IV). Since FeSe2 has a stronger reactivity than pyrite, it was proposed that greigite, rather than pyrite, was responsible for the formation of FeSe2. The findings in this study are of interest for key geochemical processes governing the mobility of toxic 79Se in the environment in presence of iron sulfides.