technetium pH-Eh diagram

[Katerina]

Hi there,

I prepared stability diagram of technetium in granitic water, I used Thermochimie database.  The final solid phase is TcO2 (aged) (I suppressed Tc(cr) and TcO2(cr)). Same diagram with MOLDATA database showed TcO2:1.6H2O (same suppressed species). My question is: what does AGED mean? Are the final solid phases different or not?

Thanks a lot,

Katerina

[Brian Farrell]

Hi Katerina,

Presumably an aged mineral is somewhat more crystalline and stable than something freshly precipitated. I’m not sure what the difference between TcO2(aged) and TcO2(cr) would be. It's not outside the realm of possibility that duplicates could exist in large datasets like these. As for TcO2(aged) vs. TcO2:1.6H2O, the latter appears to be a hydrate. To confirm for yourself, you’ll have to consult the dataset files, their original documentation (e.g. a publication, release note, etc.), or the authors themselves. We do not maintain such datasets; we simply make some published third-party datasets available in our installation, typically at the request of users or the authors.

Within the GWB, the TEdit app is extremely useful for viewing the contents of a thermodynamic dataset. You can apply a filter to see a list of only Tc-containing compounds, for example. For more information, please see sections 9.1.2, Navigating datasets, and 9.2.1, Summaries, filtering, and searching, within the GWB Essentials Guide. And in Act2, where you’re making Eh-pH diagrams, you can see a list of species and minerals considered in the calculation on the Results pane. By clicking View Results on the Plot pane, you can see a much more detailed breakdown of the equilibrium line construction.

Hope this helps,

Brian Farrell
Aqueous Solutions

[Katerina]

Thank you very much, Brian!