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mcma

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Everything posted by mcma

  1. Thank you Jia, As I mentioned (and quoted) in the original post, H2(g) was indeed not included by Dr. Gustafsson on the converted-to-GWB version of the Minteq dataset, and I wonder why. It is possible to add it and successfully have ACT2 represent the water stability space, so the omission is unclear to me. I have not been able to reach him. I hope someone else may chime in on adding hydroquinone! I have been only looking at the databases themselves, which provides a lot of information already, but I will check the user guide on this. Many thanks, MC
  2. hello GWB, I know this lower temperature database was made available to GWB users by others. However, my interests lie more on the low temperature + organics realm, which makes me gravitate to this database often. I wonder if I can get some help on modifying it. (1) The minteq database does not include the Hydrogen gas. The heading of the database reads: "Visual Minteq does not include H2(g), thus the config->options->"water limits" checkbox for GWB programs Act2 and Tact needs to be unchecked when using this dataset." This suggests there was a reason for the omision, but I was able to include the values from the Thermo database and the water limits are now represented in the plots when using ThermoMinteq as they are when working with the Thermo database. Why was this reaction omitted? (2) I am also at a loss when considering adding an organic compound to the dataset (hydroquinone). I wonder if there are recommendations on where to start or if anyone around has done it. Thanks - MCMA
  3. Can SpecE8 calculate the expected pH of a given solution, then (i.e.,given constraints only on species concentrations) ? I don't see it.
  4. Hello - On a related issue, I get an error message for plotting. The files are generated alright, but Gtplot says the input is incomplete. and the format of the gtp file is not correct. Plotting from Speci8 is not working either. Nothing happens when I press plot results. Any suggestions? Thanks, Maria C.
  5. Are there any updates or unpublished additions to the extended Lawrence Livermore thermodynamic database (thermo.com.v8.r6+.dat)?? Anyone coming across a database that includes hydroquinone speciation?? thank you -
  6. Without density and TDS defined, attempts to do the mix shows: 'the residual is too large'. These variables are ??? after running the first solution and pickup the fluid as reactant. If I define density and TDS as 1 and 0 respectively, the mix proceeds ok. If images would still be useful, I'll switch computers. Let me know. Thanks!! (Also - only if I input TDS and density from the first solution output, I can reproduce the results I get in v.6.)
  7. I am experimenting with the same mixing model in v.10 using pickup. In this case, TDS and density are choices in the basis. These remain undefined when AUTO is selected, and this prevents the mixing to occur. I am not sure what happened in v.6 with these variables, but this was not a problem.
  8. Ok- I actually tried that (i.e., start all over with the alternate thermo file) initially, but no menu appeared...maybe there is something wrong with my file. I'll try again. Thanks, Brian!
  9. Well, you can use whichever has acetate among the 2 I sent earlier. The problem arrises when changing the thermodynamics database to be the thermo_minteq. Using the regular thermo works ok.
  10. As I read and get further familiar with the way the models are made in GWB, I also would like to play with different thermodynamic datasets. Since I did this same model in Visual Minteq, I thought it would be a good idea to use that one first. (One good reason is that I am more interested in the saturation of different forms of tricalcium phosphate (including amorphous) instead of only whitlockite.) The conversion code was written by Daniel Saalfeld and Craig Bethke and is available from the VM webpage. Running the example in SpecE8 produces an error that reads 'SpecE8 stop:set_basis: lost orig basis', and the program closes. The only suspicious thing I am doing is reading this VM file from a folder outside the GWB folder, where the default thermo file lives (I had to modify the VM data base to change 'acetate' by CH3COO, but I don't have adm privileges yet in this machine to save this modified file on the GWB folder). MC
  11. Thank you Brian, I thought about the decouple choice; I"ll try that and will also include the same species in both solutions. MC
  12. I apologize in advance: I am far from familiar with GWB. The mix I'm trying to model is supersaturated in several Ca phosphate phases. Fluid A & B seem to equilibrate ok independently, but using pickup>reactants>Fluid A to react with Fluid B is not working for me. The popup-error seems to suggest the components need to be the same on both solutions -not sure if this is the case-. Modeling the solution as a single event is confusing because it looks like I can't choose CO3--, CH3COOH- and H+ simultaneously. (I am also confused by the requirement of equilibration with O2 for only 1 of the 2 fluids above.) Loading the fluid scripts one after the other and then running the equilibration, produces results albeit including several warnings of charge imbalance (which I expect) and the elimination of CO3-- from the basis; I am not sure this represents the mix I want. I haven't considered modifications to the default activities calculation, but this may be important for this example. Input is appreciated! MC FluidA.rea FluidB.rea
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