PhreeqcUsers Discussion Forum
Conceptual Models => Database selection and modification => Topic started by: segorucu on November 24, 2015, 06:39:24 PM

Hello,
I am trying to create a database for Pitzer coefficients. I wanted to ask if there is any publicly available database for the Pitzer coefficients. Is PHREEQC getting its Pitzer coefficient database from EQ3/6? Would your or their data be publicly available?
Best regards,
Emre

There is a pitzer.dat database distributed with PHREEQC. The data comes mostly from a compilation by Niel Plummer described in the documentation for the program PHRQPITZ. Tony Appelo has made recent modifications to pitzer.dat (included in current distribution) to account better for temperature and pressure, and to add silica.

Hello,
I have installed the software and found the Pitzer.dat file. A lot of the data is publicly available from other sources. However, I wanted to ask if I can copy paste this data to create my own database. The database would be used in a different commercial software package. Please let me know.
Best regards,
Emre

There are no copyrights on our software products. We ask that you give proper citation of any material that you use.

Thank you very much for note.
Best regards,
Emre

Dear Parkhurst,
In the database for Pitzer, there are 4 or 5 coefficients. I was able to find the equation for when there are 5 coefficients. Is it possible to let me know the equation when there are 4 coefficients? Is it the same as in EQ3.6? The equation they use is
x(T) = a1 + a2*(1/T  1/298.15) + a3*ln(T/298.15) + a4*(T  298.15)
where T is in K and hence the equation would be x(T) = a1 at T = 25C.
Thank you very much for your reply beforehand.
Best regards,
Emre

The equation is given in the documentation for the PITZER keyword data block.
If less than six parameters are defined, the undefined parameters are assumed to be zero.