Effects of Radiation and Temperature on Iodide Sorption by Surfactant-Modified Bentonite

Title
Effects of Radiation and Temperature on Iodide Sorption by Surfactant-Modified Bentonite
Authors
Sungwook ChoungMinkyung Kim양중석Min-Gyu KimWooyong Um
Issue Date
2014-08
Publisher
Environmental science & technology
Citation
VOL 48, NO 16, 9684-9691
Abstract
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 50, 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 γ-irradiation (60Co) resulted in significantly (∼2−10 times) lower iodide Kd 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.
URI
http://pubs.kist.re.kr/handle/201004/48051
ISSN
0013936X
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KIST Publication > Article
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