Evaporation of high saline salt lake brine containing NO3; is that possible?

[Robert Asch]

Hello all,

my name is Robert from Germany (Freiberg), i have little experience with phreeq. I am mostly using phreeq for evaporation calcualtions of natural brines from end lakes, means very high saline solutions.

Usually i am selecting the pitzer or the thereda database which works fine. But now i have a brine composition in front of me that contains Na, Ca, K, Mg, Cl, SO4 and NO3.

The issue is that the Thereda database includes some possible phases of this system (Halite, Sylvite, Carnallite, Antarcticite, Tachhydrite a.s.o) but no NO3.

My question is;

is there another database which the ions and the phases includes, and is it possible to perform such calcualtions at high saline conconetartions?

I a masking because my feeling is that for example wateq is limited to about sea water quality.

Many thanks in advance to all experts!
Robert

[dlparkhurst]

I don't know of a Pitzer database that included NO3-, although the I am sure the original works by Pitzer and colleagues included data for highly soluble NO3 salts. Perhaps someone has developed a model. To do it yourself would be a lot of work to search the literature for the parameters, and the ion-ion-ion interaction parameters may be difficult to obtain. If you are not concerned with nitrate salts, you might get by with adding a limited number of cation-anion  parameters from pure salt solutions.

The sit.dat database may be another alternative. It is derived from the same formulation as Pitzer, but has many fewer parameters.  You can always check calculations with sit.dat, excluding the nitrate, with pitzer.dat to see if results are reasonable. 

[Robert Asch]

Hello,

many thanks for the reply.

I have checked the sit database. It looks like it includes some nitrate phases.

I will try to work with it and see if there are reasonable resutls.

Best regards
Robert

[MichaelZ20]

At ResearchGate:
A Pitzer Parametrization To Predict Solution Properties and Salt Solubility in the H–Na–K–Ca–Mg–NO3–H2O System at 298.15 K
Article
Full-text available

    Feb 2018 Journal of Chemical & Engineering Data