Could anybody suggest some good literature references on the concept of "operational pH" in non-aqueous media possibly including a discussion of justified or not justified utilization of conventional pH electrodes for measuring meaningful values?
pH is per def. -loga[H3O]+ in water!!! I am not sure you will find something ... and definitively the conventional pH electrode won t work because there is water in them...
I would be happy to accept this answer as I always thought the same myself. However, I recently discovered that this is not the whole truth. For example, you may refer to "Nanoparticle Technology Handbook" edited by M. Hosokawa et al. (see the link below) On Page 189, you'll find very interesting discussion of operational pH in alumina-ethanol system. I assume that we can believe it, don't we? It also should be emphasized that we are not talking about the definition of "pH", we are talking about "operational pH". I am looking for more general and critical treatment of it, should there exist something like this.
http://books.google.de/books?id=6rcfIEclo7IC&pg=PA189&lpg=PA189&dq=%22operational+ph%22+ethanol&source=bl&ots=mVnkDJ0dY0&sig=fNEtxViFZdDyRt8ZQQ52GlLhJC8&hl=en&sa=X&ei=0rpzUtW_HIe84ATYnoGoBQ&ved=0CEkQ6AEwBA#v=onepage&q=%22operational%20ph%22%20ethanol&f=false
Electrochemistry in Nonaqueous Solutions. Kosuke Izutsu
Copyright©2002Wiley-VCH Verlag GmbH&Co.KGaA
ISBNs:3-527-30516-5(Hardback);3-527-60065-5(Electronic)
Alexandre,
I'm studying stability of colloidal particles in ethanol and want to clarify if we can represent the results of zeta-potential measurements as a standard diagram zeta-pH. The answer is seemingly yes, but then I have to learn how to properly measure the operational pH. I would not be surprised if there would be also references stating that the operational pH is a meaningless concept, however this is not the issue of the formal definition but rather of general understanding of electrochemistry in noaqueous solutions. Maybe you could suggest a more appropriate way to describe the electrostatic particle interaction in organic solvents? Any suggestions are welcome.
Sergey, thanks!
Dear Roman,
we at LUM have currently renewed interest in stability of colloidal particles in nonaqueous media. We think that we can get more direct information on colloidal stability by directly measuring it, i.e. the separation behaviour. If you like you can send us a set of samples to complement your investigations with our measurements.
Dear Roman:
The following textbook reference is not up to date but still gives a particularly clear introduction to this subject: Herbert A. Laitinen & Walter E. Harris, “Chemical Analysis ─ An Advanced Text and Reference”, 2nd ed., McGraw-Hill Kogakusha, International Student Edition, 1975, cf. section 4-10: "pH measurements in nonaqueous solvents", pp. 85-88 & 94.
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