Jump to content
Geochemist's Workbench Support Forum

Brian Farrell

Admin
  • Content Count

    983
  • Joined

  • Last visited

  • Days Won

    7

Brian Farrell last won the day on August 16 2019

Brian Farrell had the most liked content!

Community Reputation

10 Good

About Brian Farrell

  • Rank
    Advanced Member

Profile Information

  • Gender
    Male

Recent Profile Visitors

The recent visitors block is disabled and is not being shown to other users.

  1. Hi, Act2 only displays samples whose temperature is close to that of the diagram you've calculated (+/- 10 C). The samples at 76 C plot because the diagram is drawn at 76 C, but the samples that are 30-40 C will not plot. Regards, Brian Farrell Aqueous Solutions LLC
  2. Hello, Density of electrolyte solutions is not calculated in most geochemical modeling programs. It's secondary in importance to species distributions, saturation indices, and so on, but it's our opinion that a simple calculation is better than nothing. The Phillips correlation described above, which is the default method for GWB12 and older releases, was designed for geothermal applications, so it works best at higher temperatures and salinities. The correlation is known to be valid for NaCl solutions from 10 < T < 350 °C, 0.25 < m < 5 molal, and P < 50 MPa and greater tha
  3. Dear GWB users, We are pleased to announce our latest maintenance release for GWB subscribers, GWB 14.0.1. The 14.0.1 update improves appearance of legend box in scatter data plots; fixes an issue when several ChemPlugin instances share an ion exchange dataset, resolves a reliability issue in pause/resume feature in X1t/X2t, updates Rxn's outblock feature, resolves basis swapping issue when using Davis-Leckie polydentate formalism, and provides fixes for all known issues. Update from 14.0.0 at no charge to ensure you have all the newest features and bug fixes. Existing install
  4. Dear GWB users, We are pleased to announce our latest maintenance release for GWB12, GWB 12.0.6. The 12.0.6 update improves the appearance of the legend box in scatter data plots; fixes an issue when several ChemPlugin instances share an ion exchange dataset, resolves a reliability issue in pause/resume feature in X1t/X2t, updates Rxn's outblock feature, and provides fixes for all known issues. Update from 12.0.0-12.0.5 at no charge to ensure you have all the newest features and bug fixes. Existing installations should automatically update to this release, unless auto-update i
  5. Hi again, This issue was previously fixed with the release of GWB 14.0.0 for GWB subscribers. It is now available in the latest maintenance release for GWB12, 12.0.06. Regards, Brian Farrell Aqueous Solutions LLC
  6. Hi Silvain, As long as you don’t specify “free” or choose a unit that implies a free constraint (e.g. activity or pH), your constraint is for the bulk concentration of a component. To test this out, fire up SpecE8 and enter HCO3- = .001 molal pH = 6 Na+ = 1 molal balance on Cl- go You can look in the text output file to see the concentrations of several carbon species: CO2(aq) has the highest concentration at .0005060 molal, then in decreasing abundance HCO3-, NaHCO3, CO3--, and NaCO3-. Add them up and you’ll find the molal concentrations will sum to .001 molal, which is
  7. Hi Polly, For the two-layer surface complexation dataset, you need to specify a site density or densities for each sorbing mineral. If you don’t, the program can’t account for the existence of the surface. If Ferrihydrite contains both of the sites you defined, >(w1)SOH and >(w2)SOH, your entry might look like this: Ferrihydrite surface area= 600.0000 m2/g 2 sorption sites >(w1)SOH site density= .0050 mol/mol mineral >(w2)SOH site density= .2000 mol/mol mineral You should, of course, supply values appropriate for your
  8. Hi Thomas, I hope you're doing well. I happened to come across this old post and thought you might be interested to know about Phase2, an app introduced with GWB12. The program essentially traces a stacked series of reaction paths, as you'd run in React, to traverse two geochemical variables of interest. You can set up a diagram with sliding log f O2(g) and fixed pH along the y axis, then sliding pH with fixed f O2(g) along the x axis. The basis fluid is defined in terms of total concentrations, as in React, and mass is conserved throughout the calculation. You can also titrate a spe
  9. Hi Polly, Thanks for providing the thermo dataset. I'm taking a look to see if I can offer any suggestions. Regards, Brian
  10. Johan, Some time ago you tried to report the pore volumes displaced from a ChemPlugin instance in GWB12. I’m writing to let you know that GWB14 is now available, and ChemPlugin instances now plot pore volumes displaced and have the value available in the report command. Additionally, React now plots pore volumes displaced from flush and flash models. I hope you enjoy using the software. Cheers, Brian
  11. Dear GWB users, GWB14 is here! A new compute engine makes it a surface chemistry powerhouse. Plus, our latest release features user equations in GSS datasheets, high-temperature Pitzer coefficients, cluster computing, and flexible input for thermo data, just to start. Visit our GWB14 page to learn more. GWB subscribers upgrade automatically. Can’t wait another minute? Click “Check for updates” on your GWB dashboard. Not subscribing yet? Take advantage of one of our flexible plans—fixed or floating, 3 months to 3 years! Or, convert that old GWB license to a modern subscripti
  12. Hi Sanjoy, I’m writing to let you know about a new feature in the GWB14 release. You can control species loading in a calculation by specifying a temperature range over which thermodynamic data should be available. In your case, many species have thermo data available at 25 C, but not other temperatures, so your calculations at 25 C and 26 C loaded a different set of species, which caused your results to differ more than expected. By specifying a temperature range, say 10-150 C, you can ensure that any calculations within that range load the same exact set of species. It’s basically like
  13. Hi Bill, I’m writing to let you know about a new feature available in GWB14. You can control species loading in a calculation by specifying a temperature range over which thermodynamic data should be available. You can additionally force the program to always get log K values by evaluating a polynomial, even when the calculation is isothermal at a principal temperature. In this case, the program would normally use the value directly from the thermo dataset. The difference is small, but it’s why the endpoint of your polythermal path and your isothermal calculation post-pickup were slightl
  14. Hi Mauricio, I’m writing to let you know that GWB 14 is now available. The new release includes support for several different polydentate surface complexation formalisms. You had to convert the log K for a bidentate reaction in your surface dataset to be consistent with the method in GWB9, but now you can choose one of four methods consistent with your log Ks and specify that in your surface dataset. React will read the dataset and evaluate mass action laws according to the convention you specified. In your case, you could set the stoichiometric approach in the dataset’s header and
  15. Hi again Dave, Upon closer inspection, you can include a user-defined analyte in a radial plot as long as you put it in the "Components in fluid" category, since this is where the normal basis species plot in Gtplot. If you instead choose a category like "Chemical parameters" and pick Concentration for the dimension, it won't be recognized by the water chemistry plots. Still, if you want to do any thermodynamic calculations including Be, you'll need to use a dataset that includes the relevant reactions. Hope this helps, Brian
×
×
  • Create New...