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Posts posted by flo

  1. Dear all,

    I am using React 6.05 to model the concentration of Fe++ depending on pe for goethite.

    The idea is to use slide pe and keep all other concentrations constant and vary the pH in each run. Input does not seem a problem, I am surprised that the concentration of Fe++ is higher than the complete input for goethite, e.g. the concentration in mmol for goethite (not free concentration) is 63 mmol and React somehow calculates 140 mmolal Fe++ depending on pH. How is this possible and how to I manage to avoid this problem?

    I attached the script and would be glad for input.

    Thanks a lot



  2. Hi all,

    I am a little confused about the actual meaning of the following error meassage from React 6.04 using the Minteq-database saying:

    Warning: Expected a free constraint for mineral Goethite Residuals too large, 606-th interation

    I chose sodium to account for the charge balance (I did not have Cl in the system). Unfortunately I wasn't able to find a section in the manual on the charge balance and the particular error message and the respective meaning in the code. Does anyone know exactly how to deal with this?

    Thanks for the help.


  3. Hi everyone,

    I would like to model the sorption of Fe(III) species to a cell surfaces with different functional groups of which I know the adsorption constants. So I decided to start simple with a Kd model. Strangely enough I get quite obscure values that I know are wrong from experimental values.

    The following questions arose:

    Which species do I have to enter? Assume I use Fe+++ as sorbing species, one entry would look like

        charge=  3.0       mole wt.=   55.8470
        1 species in reaction
          1.000 Fe+++
        Kd=   1.58E+6

    Would I have to enter all other species relevant at the pH values as well, eg. FeOH++? Unfortunately I only have limited amounts of sorption Kds.



  4. Hello,

    In React (as well as the SpecE8 and XT modules), go to the Config menu, and choose Print Options. Change Aqueous Species to long.

    that worked well now as all the needed concentrations are now included in the output file.

    Yes, your approach is correct. It's difficult to know what the problems are with your output without seeing your script. Can you attach this?

    With the script itself I did not have any trouble, just accessing the data that should be ok now.

    Thanks again


  5. Hi,

    I would like to evaluate how the aqueous Fe(III) concentration in a mineral solution changes with pH (5-8).

    Although the concentration of aqueous Fe(III) will be quite low I need to calculate exact values and thus would like React to give the full output and not crop values smaller than 10E-8 molal. How is that done?

    For the initial setup simply giving the required concentrations and adding the sliding pH should do, right? Fe(III) is added as an aqueous species but should turn to be poorly soluble so I do not see what I am doing wrong there.

    Thanks for your suggestions.

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