Microbial metabolism in brines using GWB React - phrqpitz.tdat Vs. V8 R6.tdat

[Alero]

My question is two-fold:

1. Can I modify the phrqpitz.tdat database to include acetate and formate with limited data on virial coefficients for cation-anion or anion-anion interactions?

2. There is obvious discrepancy in species activities when I use GSS with phrqpitz.tdat versus V8 R6.tdat, and of course the absence of acetate and formate from the phrqpitz.tdat database means I cannot calculate the activities or reaction paths of these species using phrqpitz.tdat in React. Can I import data calculated using phrqpitz.tdat in GSS into React and then use V8 R6.tdat to simulate microbial metabolism and growth for the same set of data?

Anticipating your response.

[Jia Wang]

Hello Alero,

You can certainly edit the thermo dataset you wish to include interaction coefficients for acetate and formate but I would recommend being careful when editing virial datasets. These datasets can be used for modeling solution of high salinity but it can also give misleading results if the fluid composition of your system deviates drastically from the experiments used to derive the virial coefficients. 

React would not stop you from using a different thermo database for your React calculation than your GSS calculation. However, please note the Phrqpitz.tdat database uses a different activity model than thermo.V8.R6.tdat, the former uses the Harvie-Moller-Weare formalism of the virial equations and the latter uses the Debye-Huckel B-dot activity model. Thus your model results would be very different if you were switch thermo databases. Also, note that the two databases have different aqueous species, minerals, and gas species available as well. If your solution is not particularly high in ionic strength, then I would recommend just using thermo.V8.R6.tdat for both your GSS spreadsheet and your React simulation. 

Hope this helps,
Jia Wang

[Alero]

Thank you, Jia. The solutions I'm working with have ionic strengths as high as 5-6 molal, hence the need for Phrqpitz.tdat. I'll keep in mind your comment on the virial coefficients and under what experimental conditions they were derived.

Alero