Cation exchange capacity (CEC)

The study of the cation exchange capacity (CEC) and of the exchangeable cation (EC) pool of soils and clays has a long tradition starting in soil science as early as 1852. Interpretation of CEC and EC values however is often complicated. A long list of publications proves that cation exchange data are of great importance but on the other hand complicated to measure reliably.

The Federal Institute for Geosciences and Natural Resources tries to develop new CEC methods because CEC results can be used in industrial, geotechnical, and agricultural applications. Bentonites for example are used in foundry sands or studied as candidate materials for encapsulation of radioactive waste. In general CEC and EC values are useful indicators of soil fertility. The key development of the new methods is that the exchange solutions are saturated with respect to calcite prior to the experiment. The new and relatively fast one-step extraction methods are based on the two complexes Cu(II)triethylenetetramine and Co(III)hexamine. These methods called ‘Cu-trien5xcalcite’ and ‘CoHexcalcite’ may provide ‘operationally correct’ exchangeable Ca²⁺ values of calcareous soils and clays.

Literature:

• DOHRMANN, R. 1997: Kationenaustauschkapazität von Tonen - Bewertung bisheriger Analysenverfahren und Vorstellung einer neuen und exakten Silber-Thioharnstoff-Methode.- Diss. RWTH Aachen, AGB-Verlag Nr. 26, 234 S. ISBN: 3-86073-605-1
• DOHRMANN, R. 2006. Cation Exchange Capacity Methodology I: An Efficient Model for the Detection of Incorrect Cation Exchange Capacity and Exchangeable Cation Results. Applied Clay Science, 34, 31-37
• DOHRMANN, R. 2006. Cation Exchange Capacity Methodology II: proposal for a modified silver-thiourea method. Applied Clay Science, 34, 38-46
• DOHRMANN, R. 2006. Cation Exchange Capacity Methodology III: Correct exchangeable calcium determination of calcareous clays using a new silver-thiourea method. Applied Clay Science, 34, 47-57
• DOHRMANN, R. 2006. Problems in CEC determination of calcareous clayey sediments using the ammonium acetate method. J. Plant Nutr. Soil Sci., 169, 330-334
• DOHRMANN, R., KAUFHOLD, S. 2009. Three new, quick CEC methods for determining the amounts of exchangeable calcium cations in calcareous clays. Clays and Clay Minerals, 57(3), 338–352
• DOHRMANN, R., KAUFHOLD, S. 2010. Determination of exchangeable calcium of calcareous and gypsiferous bentonites. Clays and Clay Minerals, 58, 513–522
• Dohrmann, R., Genske, D., Karnland, O., Kaufhold, S., Kiviranta, L., Olsson, S., Plötze, M., Sandén, T., Sellin, P., Svensson, D., Valter, M. 2012.Interlaboratory CEC and Exchangeable Cation Study of Bentonite Buffer Materials: I. CU(II)-Triethylentetramine Method. Clays and Clay Minerals, 60, 162–175

• Dohrmann, R., Genske, D., Karnland, O., Kaufhold, S., Kiviranta, L., Olsson, S., Plötze, M., Sandén, T., Sellin, P., Svensson, D., Valter, M. 2012.

  Interlaboratory CEC and Exchangeable Cation Study of Bentonite Buffer Materials: II. Alternative Methods. Clays and Clay Minerals, 60, 176-185

• Dohrmann, R., Olsson, S., Kaufhold, S., Sellin, P. 2013. Mineralogical investigations of the first package of the alternative buffer material test – II. Exchangeable cation population rearrangement. Clay Minerals, 48, 215–233.
• Dohrmann, R., Kaufhold, S. 2014. Cation exchange and mineral reactions observed in MX 80 buffers samples of the prototype repository in situ experiment in Äspö, Sweden. Clays and Clay Minerals, 62, 357–373. doi: 10.1346/CCMN.2014.0620501
• Dohrmann, R., Kaufhold, S. 2017. Characterization of the second package of the alterna-tive buffer material experiment (ABM) – II Exchangeable cation population rear-rangement. Clays and Clay Minerals, 65, 104–121 doi: 10.1346/CCMN.2017.064052
• Frederickx, L., Honty, M. De Craen, M., Dohrmann, R., Elsen, J. 2018. Impact of mineralogy and pore water chemistry on the CEC of the Boom Clay Formation (Belgium). Clays and Clay Minerals, 66, 449–465. doi: 10.1346/CCMN.2018.064111
• KAUFHOLD, S. 2006. Comparison of methods for the determination of the layer charge density (LCD) of montmorillonites. Applied Clay Science, 34, 14-21
• Kaufhold, S., Dohrmann, R., Ufer, K., Kleeberg, R., Stanjek, H. 2011. Termination of swell-ing capacity of smectites by Cutrien exchange. Clay Minerals, 46, 411–420. doi: 10.1180/claymin.2011.046.3.411