Effect of ionic charge on effective diffusion coefficient in compacted sodium bentonite

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4 Citations (Scopus)


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 SeO32- were carried out for 1.8 Mg·m-3 by through-diffusion method. Sodium bentonite, Kunigel-V1 was used. The order of obtained De values was Sm3+>Ni2+>SeO32-. These De values were compared with those reported to date. Consequently, the order of De values was Cs+>Sm3+>HTO>Ni2+>anions(I-, Cl-, CO32-, SeO32-, TcO4-, NpO2CO3-, UO2(CO3)34-), 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.

Original languageEnglish
Pages (from-to)267-274
Number of pages8
JournalMaterials Research Society Symposium - Proceedings
Publication statusPublished - Dec 1 2000
Externally publishedYes
EventScientific Basis for Nuclear Waste Management XXIII - Boston, MA, USA
Duration: Nov 29 1999Dec 2 1999

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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