Hostname: page-component-7b7567c8c-wxvwp Total loading time: 0 Render date: 2026-11-14T23:24:41.880Z Has data issue: false hasContentIssue false

Effect of Ionic Charge on Effective Diffusion Coefficient in Compacted Sodium Bentonite

Published online by Cambridge University Press:  10 February 2011

H. Sato*
Affiliation:
Japan Nuclear Cycle Developement Institute, 4-33 Muramatsu, Tokai-mura, Naka-gun, Ibaraki-ken 319-1194, JAPAN, sato@tokai.jnc.go.jp
Get access

Abstract

Effective diffusion coefficients(De) in bentonite were measured as a function of ionic charge to evaluate the degree of surface diffusion and anion exclusion. The De measurements for Ni2+, Sm3+ and Se3 2− were carried out for 1.8Mg•m−3 by through-diffusion method. Sodium bentonite, Kunigel-V1® was used. The order of obtained De values was Sm3+>Ni2+>SeO3 2−. These De values were compared with those reported to date. Consequently, the order of De values was Cs+>Sm3+>HTO>Ni2+>anions(I−, Cl−, CO3 2−, SeO3 2−, TcO4 −, NpO2CO3 −, UO2(CO3)3 4−), showing a tendency of cations>HTO>anions. The reason that the De of Ni2+ was lower than that of HTO may be because the free water diffusion coefficient(Do) of Ni2+ is about 1/3 of that of HTO. The formation factors(FF) were in the order, Sm3+>Cs+>Ni2+>HTO>anions, indicating a possibility of surface diffusion in cations and of anion exclusion in anions. In this case, the FF of Sm3+ was approximately 5 times greater than that of HTO. However, since the Do of Sm3+ is about 1/3 of that of HTO, the De of Sm3+ may have been a little higher than that of HTO. Based on this, it is presumed that surface diffusive effect on De in bentonite is insignificant.

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Article purchase

Temporarily unavailable