Sehr geehrter Herr Blattmann:

it depends first and foremost from the matrix. If you use a "common" terrigenous sediment or soil there will by no other method  in finding a solution to the issue than applying the grain size separation by means of a settling tube (Atterberg). Smectite used to concentrate in the finest particle interval < 2 µm (the next level below is even better). It is a bit of trial-and-error approach and takes time. All attempts to separate the finest particle size showed the highest concentration of smectite-group minerals. A similar effect of a grain-size-related accumulation you may find with zircon among the heavy minerals .

If you have an "exotic" matrix enriched in "heavies" a different approach can be successful. But as I mentioned above, the groundmass and the amount of smectite present play a significant part.

Viel Erfolg

H.G.Dill

Dear Dr. Dill, Dear Dr. Towe,

Thank you very much for your replies.

There is much merit in using the traditional Atterberg or centrifugation approaches to isolate the

Thomas,

as mentioned by others above, about your only option is size fractionation.  Dispersion is key in this process, so to concentrate smectites most effectively ensure they are sodium or lithium saturated and that your dispersions are as low concentration as possible.   Inevitably, you will get other clay/fine minerals along with the smectite, but taking 0.1 micron size fraction or less (too small for Atterberg , so use a centrifuge) should give you the best possible chance of something that is mainly smectite.

Dear Stephen,

Thank you for your reply regarding of concentrion of smectite. Collecting colloidal smectite by centrifugation from sodium or lithium saturated clay makes a lot sense. Is there any particular reason for choosing sodium or lithium or for that matter perhaps potassium over the other? Is one more effective than the other at dispersing?

Best,

Thomas

Thomas,

yes lithium and sodium will give a better dispersion than other cations

steve