Examination of competitive lanthanide sorption onto smectites and its significance in the management of radioactive waste

Evgeny Galunin, María D. Alba, Maria J. Santos, Taufik Abrão, Miquel Vidal

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

The competitive effect of La and Lu (analogues of radionuclides appearing in radioactive waste) in the sorption in four smectites was examined. Sorption and desorption distribution coefficients (Kd; Kd,des), and desorption rates (Rdes) were determined from batch tests in two media: deionized water and, to consider the influence of cement leachates, 0.02molL-1 Ca. The competitive effect was lower when high-affinity sites were available, as in the water medium at the lowest range of initial lanthanide concentration, with high Kd for La and for Lu (5-63×104Lkg-1). Lower Kd was measured at higher initial concentrations and in the Ca medium, where Lu showed a stronger competitive effect. This was confirmed by fitting the sorption data to a two-solute Langmuir isotherm. The desorption data indicated that sorption was virtually irreversible for the scenarios with high sorption, with an excellent correlation between Kd and Kd,des (R2 around 0.9 for the two lanthanides). Assuming that radioactive waste is a mixture of radionuclides, and that Ca ions will be provided by the cement leachates, this would reduce the retention capacity of clay engineered barriers.

Original languageEnglish
Pages (from-to)1930-1941
Number of pages12
JournalJournal of Hazardous Materials
Volume186
Issue number2-3
DOIs
Publication statusPublished - 28 Feb 2011
Externally publishedYes

Keywords

  • Engineered barriers
  • Lanthanides
  • Radioactive waste
  • Smectitic clays
  • Sorption

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution
  • Health, Toxicology and Mutagenesis

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