Help getting started

[rwe]

OK, I am dense.

 

I just purchased GBW Essentials and am trying to get started on a few simple calculations. As a simple starting example, I am trying to input 5500 mg/kg B(OH)3, 3 mg/kg Li, 300C and would like to calculate the pH and the species distributions for boron and lithium. When I input these on the SpecE8 input screen, the output shows little more than my input info. How do I get it show the concentrations of each borate and lithium species and the at-temperature pH?

 

Second item: How do I input aqueous hydrogen since it is not on the SpecE8 input screen?

 

Thanks for helping a rookie get started,

[Tom Meuzelaar]

Hello:

 

There are likely a couple of issue with your script, however, it would be helpful if you could attach a copy of the exact script so we are comparing apples to apples:

 

1) There are few lithium aqueous species in the default database

2) You'll need to add additional components to your model if you wish to constrain pH and see some of the dissolved boron species

3) In the main input pane, you'll only see what are called 'basis species', which are essentially the building blocks of the thermodynamic database. Other aqueous species and minerals can be added to your input file via swapping. One way to add H2(aq) to your input deck is to swap it in for O2(aq).

 

I hope that helps,

 

Tom Meuzelaar

RockWare, Inc.

[rwe]

Hello:

 

There are likely a couple of issue with your script, however, it would be helpful if you could attach a copy of the exact script so we are comparing apples to apples:

 

1) There are few lithium aqueous species in the default database

2) You'll need to add additional components to your model if you wish to constrain pH and see some of the dissolved boron species

3) In the main input pane, you'll only see what are called 'basis species', which are essentially the building blocks of the thermodynamic database. Other aqueous species and minerals can be added to your input file via swapping. One way to add H2(aq) to your input deck is to swap it in for O2(aq).

 

I hope that helps,

 

Tom Meuzelaar

RockWare, Inc.

 

OK, I was able to sway H2 for O2 and when I swaped B(OH)4- or B(OH)3 I got outputs for both species but it made me define the pH. Is there a way to make the program calculate the pH simply based on input concentrations and charge balance? When I tried to swap for the other borate species it indicated they must not be in database at my temperature so I am guessing the high temp borate model is only these two species. I then proceeded to add Ca, Al, Si and a few other species to get mineral precipitates. I was happy to see that the calcium hydrolysis product appeared in the output without swapping. I could swap Al for a mineral and get that precipitate. However, there are multiple possible Al precipitates and I could only swap for one. Is there a way to input multiple precipitates and have the program calculate which ones will actually precipitate rather than being limited to only one precipitate for a given element?

[Tom Meuzelaar]

OK, I was able to sway H2 for O2 and when I swaped B(OH)4- or B(OH)3 I got outputs for both species but it made me define the pH. Is there a way to make the program calculate the pH simply based on input concentrations and charge balance? When I tried to swap for the other borate species it indicated they must not be in database at my temperature so I am guessing the high temp borate model is only these two species. I then proceeded to add Ca, Al, Si and a few other species to get mineral precipitates. I was happy to see that the calcium hydrolysis product appeared in the output without swapping. I could swap Al for a mineral and get that precipitate. However, there are multiple possible Al precipitates and I could only swap for one. Is there a way to input multiple precipitates and have the program calculate which ones will actually precipitate rather than being limited to only one precipitate for a given element?

 

To get the program to calculate pH, you'll need something to constrain the proton- that is, add H+ to your basis, and swap a component that can constrain pH. Frequently modelers will swap in something like CO2 gas fugacity or a mineral to accomplish this.

 

Regarding the precipitates, yes, GWB can calculate which are likely to form. You don't need to define them initially in the Basis pane. Simply define your water composition in the React module and it will precipitate those supersaturated phases which are thermodynamically most likely.

 

Hope that helps,

 

Tom Meuzelaar

RockWare, Inc.