React Error

[Sam]

I need to generate a speciation diagram today for sorption onto hydrous ferric oxide. I started with the example on page 210 in the textbook "Geochemical and Biogeochemical Reaction Modeling" by Graig Bethke 2nd Edition- I typed in the short sorption example from the book exactly as on the page and was surprised to get the following error . --Error:Don't know to set charge balance Species C1-- is not in the basis. What is species C1 ? I need to generate a speciation diagram for the system above but also including Al,Ca and Mg before close of business today I need help.

[Sam]

I need to generate a speciation diagram today for sorption onto hydrous ferric oxide. I started with the example on page 210 in the textbook "Geochemical and Biogeochemical Reaction Modeling" by Graig Bethke 2nd Edition- I typed in the short sorption example from the book exactly as on the page and was surprised to get the following error . --Error:Don't know to set charge balance Species C1-- is not in the basis. What is species C1 ? I need to generate a speciation diagram for the system above but also including Al,Ca and Mg before close of business today I need help

 

example on page 210: surface_data =FeOH+.dat

sorbate include

decouple Fe+++

suppress Hematite,Goethite

swap Fe(OH)3(ppd) for Fe+++

1 free gram Fe(OH)3(ppd)

[Brian Farrell]

Hi Sam,

 

Sorry your post escaped out notice. I've moved it from the archive of old posts to the GWB forum front page.

 

It looks like you didn't use the entire set of input commands. The partial script below only defines the surface to be used in your model. If you go to Craig's GBRM text, you'll find that the next few paragraphs are used to build the model step by step. First, Na+ and Cl- are added to form a simple electrolyte solution. Next, a "sliding pH" path is defined. You set an initial and final pH value - React will then incrementally increase the pH and repeatedly solve for the distribution of mass at each step. This produces the model you see in Figure 14.8. This just demonstrates how the surface sites protonate and deprotonate with changes in pH. Finally, a more complex fluid with more cations and anions is defined and the simulation repeated, producing the model shown in Figures 14.10 and 14.11.

 

The specific error you mentioned arises because there is no Cl- (chloride) in your system. This is the default ion used to enforce change balance. You can choose to turn charge balance off, or to balance on a different major ion. See the "balance" command in the GWB Reference Manual for more information.

 

As for considering sorption of additional species, you'll need to check the surface datasets (and possibly the literature) to see whether any data exists. Ca++ is accounted for, and I believe there is estimated data for Mg++ sorption to HFO, but you may need to look for Al+++ sorption data.

 

Hope this helps,

 

Brian Farrell

Aqueous Solutions LLC