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The Influence of Groundwater on the Stability of Silica Colloids

Published online by Cambridge University Press:  15 February 2011

Pirkko Holtta ,
Mari Lahtinen ,
Martti Hakanen ,
Jukka Lehto  and
Piia Juhola
Pirkko Holtta
Affiliation:
University of Helsinki, Department of Chemistry, P.O. Box 55, 00014 University of Helsinki, Finland
Mari Lahtinen
Affiliation:
University of Helsinki, Department of Chemistry, P.O. Box 55, 00014 University of Helsinki, Finland
Martti Hakanen
Affiliation:
University of Helsinki, Department of Chemistry, P.O. Box 55, 00014 University of Helsinki, Finland
Jukka Lehto
Affiliation:
University of Helsinki, Department of Chemistry, P.O. Box 55, 00014 University of Helsinki, Finland
Piia Juhola
Affiliation:
Posiva Oy, Olkiluoto, 27160 Eurajoki, Finland
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Abstract

Non-cementitious grouts have been tested in Olkiluoto for the sealing of fractures with the small hydraulic apertures. A promising non-cementitious inorganic grout material for sealing the fractures with the apertures less than 0.05 mm is commercial colloidal silica called silica sol. The potential relevance of colloid-mediated radionuclide transport is highly dependent on their stability in different geochemical environments. The objective of this work was to follow stability of silica sol colloids in low salinity Allard and saline OLSO reference groundwater (pH 7–11) and in deionized milliQ water. Stability of silica sol colloids was followed by measuring particle size distribution, zeta potential, colloidal and reactive silica concentrations. The particle size distributions were determined applying the dynamic light scattering (DLS) method and zeta potential based on dynamic electrophoretic mobility. The colloidal silica concentration was calculated from DLS measurements applying a calibration using a standard series of silica sol. Dissolved reactive silica concentration was determined using the molybdate blue (MoO4) method.

These results confirmed that the stability of silica colloids dependent significantly on groundwater salinity. In deionized water, particle size distribution and zeta potential was rather stable except the most diluted solution. In low salinity Allard, particle size distribution was rather constant and the mean particle diameter remained less than 100 nm. High negative zeta potential values indicated the existence of stable silica colloids. In saline OLSO, particle size distribution was wide from a nanometer scale to thousands of nanometers. The disappearance of large particles, decrease in colloidal particle concentration and zeta potential near zero suggest flocculation or coagulation. Under prevailing saline groundwater conditions in Olkiluoto silica colloids released from silica sol are expected to be instable but the possible influence of low salinity glacial melt water has to be considered.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1193: Scientific Basis for Nuclear Waste Management XXXIII , 2009 , 437
Copyright
Copyright © Materials Research Society 2009

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References

1 EKA Chemicals, Eka gel MEYCO MP320 http://www.colloidalsilica.com/eka.asp.Google Scholar
2 Persoff, P., Apps, J., Moridis, G. and Whang, J. M., J. Alloys Compounds, 125, 461 (1999).Google Scholar
3 Axelsson, M. and Gustafson, G., Tunneling and Underground Space Tech. 21, 499 (2006).Google Scholar
4 Funehag, J. and Gustafson, G., Tunneling and Underground Space Tech. 23, 9 (2008).Google Scholar
5 Boden, A. and Sievanen, U., SKB R–05–40/Posiva WR 2005–24 (2005).Google Scholar
6 Torstenfelt, B., Jansson, M. and Atienza, M., SKB Arbetsrapport TU–05–04 (2005).Google Scholar
7 Buddemeier, R. W. and Hunt, J. R., Appl. Geochem. 3, 535 (1988).Google Scholar
8 Kersting, A. B., Efurd, D. W., Finnegan, D. L., Rokop, D. J., Smith, D. K. and Thompson, J. L., Nature 397, 56 (1999).Google Scholar
9 Novikov, A. P., Kalmykov, S. N., Utsunomiya, S., Ewing, R. C., Horreard, F., Merkulov, A., Clark, S. B., Tkachev, V. V. and Myasoedov, B. F., Science 314, 638 (2006).Google Scholar
10 Puls, R. W. and Powell, R. M., Environ. Sci. Technol. 26, 614 (1992).Google Scholar
11 Vilks, P. and Baik, M., J. Contam. Hydrol. 47, 197 (2001).Google Scholar
12 Yamaguchi, T., Nakayama, S., Vandergraaf, T. T., Drew, D. J. and Vilks, P., J. Power and Energy Systems 2, 186 (2008).Google Scholar
13 Vuorinen, U. and Hirvonen, H., Posiva WR–2005–03 (2005).Google Scholar
14 Takala, M. and Manninen, P., Posiva WR–2006–98 (2006).Google Scholar
15 Takala, M. and Manninen, P., Posiva WR–2008–32 (2008).Google Scholar
16 Holtta, P., Hakanen, M., Lahtinen, M., Leskinen, A., Lehto, J. and Juhola, P., in Scientific Basis for Nuclear Waste Management XXXII, edited by Rebak, R.B., Hyatt, N.C. and Pickett, D.A. (Mater. Res. Soc. Symp. Proc. Volume 1124, Warrendale, PA, 2009) 1124-Q10-14.Google Scholar
17 Iler, R. K., The Chemistry of Silica, John Wiley & Sons, New York (1979).Google Scholar
18 Allard, B. and Beall, J., J. Environ. Sci. Health 6, 507 (1979).Google Scholar
19 Vuorinen, U. and Snellman, M., Posiva WR–1998–61 (1998).Google Scholar
20 Malvern Instruments Ltd., http://www.malvern.co.uk/LabEng/industry/colloids/colloids_home.htm.Google Scholar
21 Filella, M., Zhang, J., Newman, M. E. and Buffle, J., Colloids Surf. A 120, 27 (1997).Google Scholar
22 Fishman, M. J. and Friedman, L. C. (Eds.), Techniques of Water-Resources Investigations of the U.S. Geological Survey, USGS–TWRI 5, A1, 545 (1989).Google Scholar