Sorption of Sr and Cs onto Czech natural bentonite: experiments and modelling
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Within the development of deep geologic repository in the Czech Republic, the local Mg/Ca bentonite has been tested with the aim to assess its sorption qualities with regard to cations of interest for the performance assessment (PA) of the repository. The data of Sr and Cs sorption obtained by batch method were evaluated with the use of ion exchange and surface complexation models. The selectivity coefficients of exchangeable cations were determined, and the selectivity coefficient of Sr was set to be the same as for Ca. The selectivity coefficient of Cs was chosen in accordance with literature and the concentration and stability constant of the surface complex was fitted. One-site ion exchange model for Sr sorption was able to predict the observed Kd dependence on solid-to-liquid ratio. Two-site ion exchange/surface complexation model for Cs sorption simulated the dual sorption mechanism of Cs adequately, thus the predictive ability was lower due to the fact that the protonation of edge sites or competition with Na ion was not taken into account.
KeywordsBentonite Ion exchange Surface complexation
This work is partially a result of Radioactive Waste Repository Authority Project “Research Support for Safety Evaluation of Deep Geological Repository” and partially a result of Grant No. SGS16/250/OHK4/3T/14 provided by the Grant Agency of the Czech Technical University in Prague.
- 2.Khan SA, Riaz-ur-Rehman, Khan MA (1996) Sorption of strontium on bentonite. Waste Manag 15:8Google Scholar
- 10.Van Loon LR, Baeyens B, Bradbury M (2005) Diffusion and retention of sodium and strontium in Opalinus clay: comparison of sorption data from diffusion and batch sorption measurements, and geochemical calculations. Appl Geochem 20:12Google Scholar
- 13.Yu J, Neretnieks I (1997) Diffusion and sorption properties of radionuclides in compacted bentonite. SKB technical report 97-12Google Scholar
- 24.Garrido V, Martinez M, De Pablo J, Eriksen TE, Duro L, Bruno J (1998) Sorption mechanism of Sr(ll) in natural bentonite. Goldschm Conf Toulouse 62:502–503Google Scholar
- 26.Kroupová H, Štamberg K (2005) Experimental study and mathematical modeling of Cs(I) and Sr(II) sorption on bentonite as barrier material in deep geological repository. Acta Geodyn Geomater 2:138Google Scholar
- 28.Červinka R, Gondolli J (2015) Modelování pórové vody kompaktovaného bentonitu BaM.ÚJV Řež a. s. Report no. 14407Google Scholar
- 29.Carter DL, Mortland MM, Kemper WD (1986) Specific surface. In: Klute A (ed) Methods of soil analysis, part 1. Physical and mineralogical methods, chapter 16, 2nd edn. American Society of Agronomy–Soil Science Society of America, Madison, pp 413–423Google Scholar
- 33.Parkhurst DL, Appelo CAJ (2013) Description of input and examples for PHREEQC version 3—a computer program for speciation, batch-reaction, one-dimensional transport, and inverse geochemical calculations. U.S. Geological Survey Techniques and Methods, book 6, chapter A43, p 503Google Scholar
- 34.Bradbury M, Baeyens B (2004) Near field sorption data bases for compacted MX-80 bentonite for performance assessment of a high-level radioactive waste repository in Opalinus clay host rock. PSI Bericht Nr. 03-07Google Scholar
- 38.Bradbury MH, Baeyens B (2002) Porewater chemistry in compacted re-saturated MX-80 bentonite: physico-chemical characterisation and geochemical modelling. J Contam Hydrol 61:02Google Scholar