Effective removal of iodate by coprecipitation with barite: Behavior and mechanism
Effective removal of iodate by coprecipitation with barite: Behavior and mechanism
复制标题
重晶石共沉淀有效去除碘酸盐：行为和机制
DOI：
10.1016/j.chemosphere.2020.129104
复制
发表时间：
2021
期刊：
影响因子：
8.8
通讯作者：
Kozai Naofumi
中科院分区：
文献类型：
--
作者：
Tokunaga Kohei;Takahashi Yoshio;Tanaka Kazuya;Kozai Naofumi
放射性碘（129 I）由于其在环境中的高流动性和长期放射毒性而引起极大关注。然而，缺乏从水溶液中去除碘酸盐（IO3−）的有效技术。本研究旨在开发一种利用硫酸钡去除污染溶液中放射性碘酸根的新技术。我们在分子水平上研究了重晶石共沉淀碘酸盐的机理，以确定去除碘酸盐的最佳条件。结果表明，即使在竞争性阴离子存在下，共沉淀法也能有效地去除水中的碘酸根。基于我们的方法与以前的技术的比较，在10 mmol L−1Cl−下，重晶石的碘酸盐去除效率被确定为比水滑石状层状双氢氧化物高约两个数量级。扩展X射线吸收精细结构分析表明，当碘浓度较低时，碘酸根取代了重晶石的硫酸根位置，与重晶石晶格紧密结合。SO42−位上IO3−取代的电荷补偿问题是通过在最近的Ba2+位上取代Na+−IO3−对来实现的。由于碘酸盐与重晶石的高去除效率和强结合，与重晶石的共沉淀是从被碘酸盐污染的各种水溶液中去除放射性碘酸盐的有前途的工具。
Radioactive iodine (129I) is of great concern owing to its high mobility in the environment and long-term radiotoxicity. However, there is a lack of effective techniques for removing iodate (IO3−) from aqueous solution. This study aims to develop a new technique for removing radioactive iodate from contaminated solution by using barite (BaSO4). We examined the coprecipitation mechanism of iodate by barite at the molecular level to determine the optimum conditions for iodate removal. Results showed that iodate was effectively removed from the aqueous solution by coprecipitation even in the presence of competitive anions. Based on comparison of our method with previous techniques, the iodate removal efficiency by barite was determined to be about two orders of magnitude greater than that by hydrotalcite-like layered double hydroxide at 10 mmol L−1Cl−. Extended X-ray absorption fine structure analysis indicated that the incorporated iodate was strongly bound to the crystal lattice of barite by substituting the sulfate site in the structure when the iodine concentration was low. The charge compensation problem from the IO3−substitution in the SO42−site was achieved by the substitution of Na+−IO3−pairs at the nearest Ba2+site. Given the high removal efficiency and strong binding of iodate to barite, coprecipitation with barite is a promising tool for removing radioactive iodate from various aqueous solutions contaminated with iodate.