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How can i custom my own database?

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Hi everyone,

After learning the tutorial about “Editing thermo”, i noticed that the range of temperature and pressure are limited. I do know how to modify the logK vaules using SUPCRT92, but i am not sure how to change the parameters of Deby-Huckel parameters/CO2activity coefficient terms and water activity coefficient terms, especially the CO2 1,2,3,4s and H2O 1,2,3,4s.

Where can i find those parameters or is there a software can generate them?


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Guest Melika Sharifi

Dear Yzdm,


I am not sure whether the change of activity coefficients of water and CO2 and Debye-Huckel parameters with pressure and temperature are considered in anyway in programs making GWB-formatted datasets at arbitrary temperatures and pressures. I would suggest that you check the DBCreate and K2GWB programs to see if they are considering the effect of pressure and temperature on the activity coefficients and Debye-Huckel parameters in producing GWB-formatted thermo datasets. If not, you may check these two papers and see if they have the information you are looking for:


1- Helgeson, H.C., 1969, Thermodynamics of hydrothermal systems at elevated temperatures and pressures. American Journal of Science 267, 853-877

2- Helgeson, H.C. and D.H. Kirkham, 1974, Theoretical prediction of the thermodynamic behavior of aqueous electrolytes at high pressures, and temperatures, II. Debye-Huckel parameters for activity coefficients and relative partial molal properties. American Journal of Science 274, 1199-1261


Also, I think you will find section 8.1.2 of Craig Bethke's Geochemical and Biogeochemical Reaction Modeling text on B-dot model helpful.


Hope this helps.



Melika Sharifi

Aqueous Solutions LLC

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