Problems with Th(CO3)5(6-) species (React)

[bine]

Dear support team,

 

recently I am having trouble in calculating the solubility of Th(OH)4(am) depending on the carbonate concentration. The parameter file works well if I only include either carbonate without thorium or thorium without carbonate. If I include both I get the message "React stop: calc_hmw: max charge too large". With the help of a colleague I figured out that this is probably caused by the species Th(CO3)5(6-).

I am using react version 8.0.12 and colleague using version 9 had the same problem.

 

Do you have any idea how we can solve this issue?

 

Thanks in advance for your help!

Best regards,

Christiane

Th_CO3_titration.rea

[Brian Farrell]

Hi Christiane,

 

You are correct in that Th(CO3)5(6-) is the source of the problem. When the HMW calculations were originally coded into the GWB, it was a safe bet that species with charges of +/- 6 wouldn't be seen, but since that time the applications of the ion interaction models have expanded significantly. We'll include a fix in our next maintenance release of version 9.

 

By the way, you might want to set a free constraint for OH-, instead of a total concentration.

 

Regards,

 

Brian Farrell

Aqueous Solutions LLC

[bine]

Dear Brian Farrell,

 

thank you for your quick reply and for fixing this task in the next maintenance release for version 9.

We`ve already been thinking about perchasing an upgrade for our version 8.

The idea with the free concentration for OH- is a good one. I will try it out for my next calculations.

 

Best regards,

Christiane

[Frank Bok]

Hi Brian et al.,

 

I'm happy to hear that you will fix this problem within the next maintenance release because I got the same problem here with a database including e.g. (UO2)3(CO3)6<6-> species.

 

Thanks!

Frank

[Frank Bok]

Hi Brian et al.,

 

Thank you very much for fixing this bug! Actually we (the THEREDA database project, www.thereda.de) are working on our Pu/Th/Np(IV) Pitzer data release where these highly charged species are relevant.

Best wishes!

 

Frank

[Brian Farrell]

Hi Frank,

 

Glad to hear it's useful in your work, and to see THEREDA making new thermo datasets freely available.

 

Cheers,

Brian