[OLD] Uranium phosphate data

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From: Wang Lian

Subject: uranium phosphate thermo data

The default database 'thermo.dat' associated with the release 3.0 is different from that of Livermore's from the web. The stability constants for Uranium phosphate complexes, e.g., UO2(H2PO4)H3PO4+ and UO2(H2PO4)2 are much higher (40 orders of magnitudes) than those compiled in the 'thermo_com_v8_r6.full'. Is there something wrong? What is the general criteria to 'moderate' the full database to the default one?

 

From: Craig Bethke

Subject: Re: uranium phosphate thermo data

The default database (thermo.dat) is not a subset of the updated databases available for download from LLNL, but an earlier version. We try not to change thermo.dat, so that users' results don't change when they install a new GWB release. The updated LLNL databases are considerably expanded from thermo.dat, especially for the radioactive elements, and contain a number of corrections. In the case of UO2(H2PO4)H3PO4+, the updated dataset (thermo.com.V8.R6.full) contains data from the Grenthe et al., 1992 compilation for uranium species that was not available when thermo.dat was compiled (1986). As to why the log K's differ by forty orders of magnitude(!), perhaps someone working in U chemistry would like to comment.