Effective removal of iodate by coprecipitation with barite: Behavior and mechanism. (March 2021)

• Record Type: Journal Article
• Authors: Tokunaga, Kohei; Takahashi, Yoshio; Tanaka, Kazuya; Kozai, Naofumi
• Is Part Of: Chemosphere. Volume 266(2021)
• Publication Date: 2021-03
• Subjects: Barite -- Iodate -- Coprecipitation -- EXAFS; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2020.129104
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Radioactive iodine ( 129 I) 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 −1 Cl − . 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 SO4 2− site was achieved by the substitution of Na + −IO3 − pairs at the nearest Ba 2+ 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. Graphical abstract: Image 1 Highlights: A new technique for removing radioactive iodate from contaminated solution by coprecipitation with barite. Iodate was removed from aqueous solution by coprecipitation with barite even in the presence of competitive anions. Iodate was substituted for SO4 2− site in the barite structure. Charge compensation was achieved by the substitution of sodium Na + -IO3 − pairs at the nearest Ba 2+ site.