Help on Basaltic Glass Reaction

[thais98]

Hello,

I am having some doubts on how to add a basaltic glass in the reactant pane. I've seen some other posts regarding basaltic glass reaction, but I didn't understand how to add the basaltic glass oxides in the thermo.dat. Or should I rather input the minerals that make up the basaltic glass? Apart from the glass, I am adding the other minerals from the basalt. So, could I add to the basalt's minerals, e.g to Albite, a % of the basaltic glass (that would represent % of Al and K for example?)? But then, the surface area of the basaltic glass would be totally different from the other minerals , right? 

[Jia Wang]

Hello Thais,

To add oxides to a thermo.tdat, you can navigate to the Oxides section and add a new entry. Oxides can be used as a reactant to change the composition of your system but they are different from a mineral (such as albite). You will notice that the there are no places to include log ks in the thermo databse for an oxide entry because they are not thermodynamically stable. Oxides also do not have a surface area associated with its entry. For more information regarding this section in the dataset, please see section 3.4 Species and reactions in the GWB Reference manual.

I am not really sure what you mean by " So, could I add to the basalt's minerals, e.g to Albite, a % of the basaltic glass (that would represent % of Al and K for example?)?". Albite is a mineral and you can write the reaction for any mineral with aqueous species, other minerals, basis species, redox species, gases and electron, but not oxides.

You can add both minerals and oxides in the Reactants pane. A good example of a glass dissolution simulation titled "How do I simulate glass dissolution?" can be found on the GWB tutorials page under the section Reaction Path Modeling. Note that you are simply entering a mass for each oxide. Oxides are not available to be kinetically constrained. If you would like further troubleshooting, please provide more details regarding the problem and any input files.

Hope this helps,
Jia Wang

[thais98]

Hello,

 So the best way to add basaltic glass is by adding the oxides in the reactant pane?

11 hours ago, Jia Wang said:

I am not really sure what you mean by " So, could I add to the basalt's minerals, e.g to Albite, a % of the basaltic glass (that would represent % of Al and K for example?)?

Considering that basalt glass is made of different oxides, I could take a % of it that relates to another mineral and add this % of basaltic glass to the mineral's composition. I hope you could understand it. 

I will try to react the oxides and see the output, if I get any problems I will post it here!

Thank you !

[thais98]

Hello,

I am reading an article and the author adds the kinetic parameters to the basaltic glass, and also the logK, which is -99. So, the author added the glass as a mineral in the thermodat? But adding the basaltic glass as a mineral is too complex, right? My goal is to try to do the same process to the glass as I did to the minerals of the basalt, using kinetic.  I attached the Table of the kinetic parameters he used for the reaction. 

[Jia Wang]

Hello Thais, 

You can add the glass as a mineral reaction in your thermo database if you want and model its dissolution with kinetics. I am guessing that's what the author of this paper did but can't know for sure. Adding a new mineral into the database typically requires you to provide the mineral reaction, mol weight, and the log ks. You can edit a thermo dataset easily with the TEdit application. A good place for information and examples is the chapter 9. Using TEdit in the GWB Essentials user guide. You can also find some examples our tutorials page. 

Hope this helps,
Jia 

[thais98]

Hello,

Yes, I tried adding the glass in the thermo database. But, for each element in the basalt glass formula, there's a specific number of molecules. Ca0.015Fe0.095 Mg0.065Na0.025 K0.01Al0.105 S0.003Si0.5O1.35 : this is the formula of the basaltic glass. I'm not sure how to add those values in the thermo database.                                           

Thank you

Thais