concentration in the output does not match concentration in the input

[flo]

Dear all,

I am using React 6.05 to model the concentration of Fe++ depending on pe for goethite.

The idea is to use slide pe and keep all other concentrations constant and vary the pH in each run. Input does not seem a problem, I am surprised that the concentration of Fe++ is higher than the complete input for goethite, e.g. the concentration in mmol for goethite (not free concentration) is 63 mmol and React somehow calculates 140 mmolal Fe++ depending on pH. How is this possible and how to I manage to avoid this problem?

I attached the script and would be glad for input.

Thanks a lot

Florian

goethite.rea

[Tom Meuzelaar]

Dear all,

I am using React 6.05 to model the concentration of Fe++ depending on pe for goethite.

The idea is to use slide pe and keep all other concentrations constant and vary the pH in each run. Input does not seem a problem, I am surprised that the concentration of Fe++ is higher than the complete input for goethite, e.g. the concentration in mmol for goethite (not free concentration) is 63 mmol and React somehow calculates 140 mmolal Fe++ depending on pH. How is this possible and how to I manage to avoid this problem?

I attached the script and would be glad for input.

Thanks a lot

Florian

Hi Florian:

This is part of the problem with not setting Goethite as a free constraint. During initial speciation, React not only dissolves all of the Goethite you've initially defined, but it must dissolve significant additional Goethite, leaving a negative mineral mass, in order to bring Fe++ concentrations to equilibrium for the conditions that you've specified.

I hope that helps,

Tom Meuzelaar

RockWare, Inc.