Accéder au contenu
Merck

Effects of radiation and temperature on iodide sorption by surfactant-modified bentonite.

Environmental science & technology (2014-08-05)
Sungwook Choung, Minkyung Kim, Jung-Seok Yang, Min-Gyu Kim, Wooyong Um
RÉSUMÉ

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 ((60)Co) 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.

MATÉRIAUX
Référence du produit
Marque
Description du produit

Sigma-Aldrich
Iodure de potassium, ACS reagent, ≥99.0%
Sigma-Aldrich
Iodure de potassium, ReagentPlus®, 99%
Sigma-Aldrich
Iodure de potassium, anhydrous, free-flowing, Redi-Dri, ACS reagent, ≥99%
Sigma-Aldrich
Iodure de potassium, puriss. p.a., reag. ISO, reag. Ph. Eur., ≥99.0%
Sigma-Aldrich
Iodure de potassium, anhydrous, free-flowing, Redi-Dri, ReagentPlus®, 99%
Sigma-Aldrich
Iodure de potassium, puriss., meets analytical specification of Ph. Eur. BP, USP, 99.0-100.5% (calc. to the dried substance)
Sigma-Aldrich
Iodure de potassium, ≥99.99% trace metals basis
Sigma-Aldrich
Iodure de potassium, BioUltra, ≥99.5% (AT)
Sigma-Aldrich
Iodure de potassium, suitable for plant cell culture
Supelco
Iodure de potassium, Pharmaceutical Secondary Standard; Certified Reference Material
Sigma-Aldrich
Iodure de potassium, puriss., meets analytical specification of Ph. Eur. BP, USP, 99.0-100.5% (calc. to the dried substance)
Sigma-Aldrich
Iodure de potassium, AnhydroBeads, −10 mesh, 99.998% trace metals basis
Sigma-Aldrich
Iodure de potassium, BioXtra, ≥99.0%
Sigma-Aldrich
Iodure de potassium, tested according to Ph. Eur.