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How to set up an input file with many (7+) mineral phases?


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Hello,

I would like to set up a calculation of a natural scenario that includes sorption (SCM) onto several natural occuring mineral phases (Quartz, Albite, Orthoclase, Microcline, Illite, Kaolinite, Montmorillonite). Including so many minerals using swap 'mineralname' for SiO2(aq), Al+++ etc. does not work. There are simply not enough elements to swap all in.

Can you give me a hint how to do this?

Many thanks in advance and best regards,
Frank

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Hello Frank,

If you would like to set these minerals for just surface complexation reactions, you can add each as a kinetic reactant and set the kinetic rate constant (and effectively the reaction rate) to 0 so that the mineral will not precipitate or dissolve but the mineral surfaces will be able to form complexes.

You might find it helpful to create a surface dataset to describe the complexation reactions for each sorbing mineral. That way you can load each dataset into your simulation as needed. The GWB apps allow multiple surface datasets to be loaded in the same simulation. 

Best regards,
Jia Wang
Aqueous Solutions LLC

 

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Dear Jia,

many thanks for the quick answer, I will try it. My other concerns are on data consistency for the sorption data. Not only the available SCM data is far from beeing complete (here I have to finde a way using chemical analogues) but it is also scattered over several surface complexation models (most double layer and triple model). Here I have to check in the consequences of mixin different models in a sumilation. But that's just part of my work.

Many thanks and best regards,

Frank

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Dear Jia,

I have successfully implemented this solution - thank you again! Since I want to run a large number of individual calculations here (>>100,000)  automatized:
Is there also a solution for SpecE8 or does including a larger number of minerals only work with React? As this would reduce computing time...

Many thanks and best regards,

Frank

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Hello Frank,

I am glad to hear that this worked for you. React allows users to set up an initial geochemical system and then alter it by setting up various types of reaction paths. Most of these reaction paths are specified in the Reactants pane, such as titrating in solutes, kinetic reactions, sliding activity/pH paths, and etc. The strategy with adding minerals as kinetic reactants and setting a zero reaction rate effectively sets them as inert minerals to provide a surface for complexation reactions. 

SpecE8 on the other hand calculates the distribution of mass in solution and on mineral surfaces given component concentrations statically. It does not carry the concept of reaction paths as React does. Therefore, the same strategy with using kinetic minerals wouldn't work in SpecE8. The options to provide mineral surfaces for complexation reactions or sorption would be to either swap the mineral into the basis or designate an inert mineral volume. The latter case would not be useful if you're looking at triple or double layer complexation models since they require a specific sorbing mineral. 

I have a couple of suggestions that may help speeding up and automating your calculations. If nothing is set to alter your system in React, you may be able to speed up your calculation by running "go initial" instead of "go". This way, React will calculate the initial equilibrium state of your system without running the reaction steps with all the kinetic minerals being essentially inert. 

If you're performing this type of calculation on a large number of samples, you might consider automating the process with the GWB Plugin feature or a Remote Control control script for Multiple Analyses. These features will also allow you to have more control over the data output from React runs. For more information and example on these features, please see the GWB Reference manual. 

Another option that may work well, depending on the complexity of your calculations, is to use GSS. You can add your sample analyses into a GSS spreadsheet and launch/run each sample in React. Before doing so, you can also add surface datasets in the Header command box and set the kinetic minerals for SCM in the Trailer command box. For more information on this, please see section 3.5 in the GWB Essentials User Guide. 

Hope this helps,
Jia

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Hello Jia,

many thanks for these large amount of really useful information! I actually use the Python GWB plugin. Works great!

Many thanks and best regards,

Frank

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