Choung, Sungwook Kim, Minkyung Yang, Jung-Seok Kim, Min-Gyu Um, Wooyong 2024-01-20T09:03:23Z 2024-01-20T09:03:23Z 2021-09-02 2014-08-19 0013-936X https://pubs.kist.re.kr/handle/201004/126460 Bentonite, which is used as an engineered barrier in geological repositories, is ineffective for sorbing anionic radionuclides because of its negatively charged surface. This study modified raw bentonite using a cationic surfactant (i.e., hexadecyltrimethylammonium [HDTMA]-Br) to improve its sorption capability for radioactive iodide. The effects of temperature and radiation on the iodide sorption of surfactant-modified bentonite (SMB) were also evaluated under alkaline pH condition similar to that found in repository environments. Different amounts of surfactant, equivalent to the SO, 100, and 200% cation-exchange capacity of the bentonite, were used to produce the HDTMA-SMB for iodide sorption. The sorption reaction of the SMB with iodide reached equilibrium rapidly within 10 min regardless of temperature and radiation conditions. The rate of iodide sorption increased as the amount of the added surfactant was increased and nonlinear sorption behavior was exhibited. However, high temperature and gamma-irradiation (Co-60) resulted in significantly (similar to 2-10 times) lower iodide K-d values for the SMB. The results of FTIR, NMR, and XANES spectroscopy analysis suggested that the decrease in iodide sorption may be caused by weakened physical electrostatic force between the HDTMA and iodide, and by the surfactant becoming detached from the SMB during the heating and irradiation processes. English American Chemical Society NATURAL ORGANIC-MATTER RADIOIODINE I-129 MOLECULAR ENVIRONMENT ADSORPTION CLAY RADIONUCLIDES ORGANOCLAYS MECHANISM SEDIMENTS BEHAVIOR Effects of Radiation and Temperature on Iodide Sorption by Surfactant-Modified Bentonite Article 10.1021/es501661z 1 Environmental Science & Technology, v.48, no.16, pp.9684 - 9691 Environmental Science & Technology 48 16 9684 9691 scie scopus 000340701800089 2-s2.0-84906251815 Engineering, Environmental Environmental Sciences Engineering Environmental Sciences & Ecology Article NATURAL ORGANIC-MATTER RADIOIODINE I-129 MOLECULAR ENVIRONMENT ADSORPTION CLAY RADIONUCLIDES ORGANOCLAYS MECHANISM SEDIMENTS BEHAVIOR