Thermo data set

[Sam]

I am new to GWB.I am trying to use Act2 to draw an Eh-pH diagram at 25 deg C for the system Cu-Fe-H2S-HCl-H2O.I modified a Thermodat set to use for the plot.First Act2 said it could not find the data set. Now when I launch Act2 I get an error message as follows:"Warning :database C:\Program Files\Gwb\Gdata\Cu_Fe_S_HCl_H2O_Eh-pH.dat doesn't match debye-huckel model" when I click on the OK button it gives another error: "Exit Act2 stop:bad thermo database Act2 ending" and it does not allow Act2 to be launched anymore.I do not understand these errors or how to fix them- please I need help to produce these Eh-pH plots today- please help.

[Brian Farrell]

Hi Sam,

 

You should double check the modifications you've made, ensuring they follow the pattern of other datasets and the format detailed in the Appendix to the GWB Reference Manual. An error might be something as simple as not enough numbers after a decimal point. If you post your thermo dataset I can take a look at it.

 

If you can't get your own dataset going right away, you might use one of the defaults like thermo.dat or thermo.com.v8.r6+. You can always use the "alter" and "suppress" commands to suit your needs.

 

Hope this helps,

 

Brian Farrell

Aqueous Solutions LLC

[Sam]

Hi Sam,

 

You should double check the modifications you've made, ensuring they follow the pattern of other datasets and the format detailed in the Appendix to the GWB Reference Manual. An error might be something as simple as not enough numbers after a decimal point. If you post your thermo dataset I can take a look at it.

 

If you can't get your own dataset going right away, you might use one of the defaults like thermo.dat or thermo.com.v8.r6+. You can always use the "alter" and "suppress" commands to suit your needs.

 

Hope this helps,

 

Brian Farrell

Aqueous Solutions LLC

[Sam]

Hi Brian,

 

I modified thermo.dat data set by adding two basis species ,CuS and H2S(g), to the list of basis species making sure I followed the same format and changed the number of basis species and Act2 still said the dataset was bad. I need to generate Eh-pH plots for the system Cu-Fe-S-Hcl-H2O at 25 deg C.If I use the thermo.dat data set as the default dataset(no modification) the Eh-pH plot that results only uses one mineral , chalcopyrite, in computing the Eh-pH plot- that is what Act2 says when you click on the Results pane after the plot is done.Is there a way to modify the thermo.dat dataset to be able to generate these Eh-pH plots for the Cu-Fe-S-HCl-H2O system ?

 

Sam

[Brian Farrell]

Hi Sam,

 

If you attach your modified dataset I can take a look, but I don't think you want to add H2S(g) or CuS as new basis species. In fact, H2S(g) and Covellite (CuS(s)) are already included in thermo.dat under gases and minerals, respectively. You typically wouldn't want to add these as new basis species anyway, since they can be formed from combinations of the existing basis species H+, SO4--, O2(aq), Cu+, and H2O. Instead, you would add reactions for new redox species (a basis species in an alternative redox state), aqueous species, minerals, or gases.

 

If you need to modify a reaction log K, you can do so from the Config menu - Alter log Ks...

 

Not sure why your script with thermo.dat only included one mineral, although it's possible under the specified conditions that is the only stable mineral. If you attach your script I can take a look. You might also take a look at Figures 5.2 or 5.5 in the GWB Essentials Guide for example redox-pH diagrams in multi-element systems.

 

Hope this helps,

Brian