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Modeling a geothermal brine. CO2 in solution changes hugely when steam is separated. Calculated fugacity of CO2 using another program, entered fco2 value into React. Resulting output file is attached, mt43_03.txt, with the corresponding .rea file copied into it between the lines of **********. Took calculated concentration of CO2 in solution (including HCO3-) as reported in "Original basis - HCO3- " and "Elemental composition - Carbon" and replaced fco2 with that amount of CO2(aq). (Bicarbonate not specified as a separate species; pH is controlled by specifying OH- which represents total alkalinity of the brine.) This calculation gave a much higher pH value, even through Original basis and Elemental composition values are the same. Attached file is mt43_03c.txt Only red flag I see is a negative value for "Original basis - H+" in the latter calculation. This looks like a NASTY error in React. Is there a patch or easy work-around ? I have had similar problems using specifying values of fugacity of H2S. mt43_03.txt mt43_03c.txt

Hi, I am interested in using GWB to model CO2-NH3-H2O vapor-liquid equilibria using Pitzer coefficients. Using thermo_phrqpitz.dat, this doesn't seem to be possible. Is their another data set that would allow me to do this? If not, would it be possible to edit one of the data sets in such a way to make this possible. It's worth noting that I'd like to include the carbamate ion species (e.g. H2NCOO-). There was a recent publication in the International Journal of Greenhouse Gas Control published recently (Author: Yin Xu, Title: Modeling of the NH3-CO2-H2O vapor-liquid equilibria behavior with species-group Pitzer activity coefficient model), that I though might be useful in this task. If the vapor-side modeling is not feasible, there would still be value in just modeling the closed aqueous system. If anyone has any suggestions, please let me know. Thanks!