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recreation of 1978-1979 experiments

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Hello Tomas,


There are quite a few ways you can create speciation vs. pH plots. The easiest method is to set up a reaction path model and slide the pH (vary the pH from 2 to 12) using the GWB program React which is included in our Standard package. Check out example 3.6 in the Reaction Modeling Guide (you can access PDFs of the user’s guides from the Help menu of any GWB program, or from the Docs pane of the GWB dashboard).


log ug/kg U++++ = -5

Na+ = .2 molal

balance on Cl

pH= 2

slide pH to 12


In the free GWB Student Edition, you can’t create reaction paths but you can create the plots in steps using SpecE8. To do this, setup an equilibrium model for your fluid and run the model at one pH and export the numerical results to excel. You can repeat the runs varying the pH values and exporting the results each time.


log ug/kg U++++ = -5

Na+ = .2 molal

balance on Cl


pH= 2






Alternatively, you calculate the concentration of uranyl complexes in GSS directly. You can enter a sample in GSS the same way you define a fluid in SpecE8 or React. If you copy your sample multiple times and change the pH for each, you can calculate uranyl species concentrations for all of your sample entries by selecting + analyte> Calculate... GSS sends the data entered in your spreadsheet to SpecE8 calculates the species concentration values and displays the value back in your GSS file. To graph your GSS data select Graphs> XY plot to view a plot of your data in Gtplot.


To add the balance on Cl- command in GSS go to: Data>Constraints> Trailer commands


If you are interested in upgrading to our Standard package you or your advisor may be eligible for an academic discount on a purchase of a new license. Please visit http://gwb.com/requests.php to request a quote.


Kind regards,



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