Eh-pH diagram

[Tuan Tran]

Dear ad,

When I use Act2 of GWB for creating the Pourbaix diagram for Fe and Mn. I have a question here. 

For Fe-Mn-H2O system, how the activity of Fe and Mn is calculated before I put the number of this for choosing activity or log activity?

If I create the above system, for Fe, I have to choose as Fe++ and Mn as Mn++?

Thank you so much for your help,

Best regards,

Tuan Tran.

[Jia Wang]

Hello Tuan,

Act2 makes calculations for analytical solutions to draw equilibrium lines to show predominant species of the highest activity. Therefore, you should be using the activity of the predominant Fe or Mn species in your system for Act2 calculation.

If you don't know the activity of your predominant species and you have a chemical analysis for your fluid, you can run a speciation calculation using SpecE8 to calculate it. You can plot the result from SpecE8 using Gtplot and configure the plot to show species activities. FYI, you can filter on the plot dialog to show you Fe related or Mn related species only. For more information, please see section 7 Using SpecE8 and section 8.2 Editing Gtplot appearance in the GWB Essentials User Guide. 

Hope this helps,
Jia Wang