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Melika Sharifi

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Everything posted by Melika Sharifi

  1. Dear M.Scharrer, Thanks for attaching your scripts. For better comparison, I would suggest that you choose log f O2(g) as x-axis in both scripts. I noticed that the "extrapolate logKs" option was not checked in either of your scripts. After making the changes mentioned above, I get almost similar speciation in both graphs at 100 C and pH7. If you look at your Act2 diagram, you will see speciation of As at pH 7 (the same pH you have chosen in Tact) is the same as speciation of As at 100 C (the same temperature you have chosen in Act2). Please note that you can not compare your Act2 and Tact results unless you are looking at the same parameters in both (in this case is pH and Temperature). Hope this helps. Bests, Melika Sharifi Aqueous Solutions LLC
  2. Dear Bruce, Thanks for attaching the error message. All .sdat tedit datasets include in the Header a reference to the thermo dataset that supplied all the aqueous species and minerals involved in the surface complexation reactions. The error you are receiving is saying that As(OH)3 is not included in the thermo dataset you are using. Hope this helps. Bests, Melika Sharifi Aqueous Solutions LLC
  3. Hi Abdul, Could you, please, give us more information about the version of the GWB and the type of operating system you are using? Are other programs (i.e. GSS, Tact, Act2, etc.) working? How are you trying to open the Gtplot? Thanks, Melika Sharifi Aqueous Solutions LLC
  4. Thanks for sending us the activation code. You are all set, now. Bests, Melika Sharifi Aqueous Solutions LLC
  5. Could you, please, email your student license activation code to support@gwb.com? Thanks, Melika Sharifi Aqueous Solutions LLC
  6. Dear Foramurber, Could you, please, take a screenshot of the error message and attach it here? Thanks, Melika Sharifi Aqueous Solutions LLC
  7. Hi Wonjung88, If you take a closer look at the tutorial Pourbaix diagram, you will see the "speciate over x-y" option is on for SO4--. If you know that your complexing species reacts under changing Eh or pH, you can include that in your graph using the "speciate over x", "speciate over y", or "speciate over x-y" option from the pulldown next to where you define the activity of your complexing species. Bests, Melika Sharifi Aqueous Solutions LLC
  8. Dear Pavan, Thanks for the additional info on your work. The basis pane is where you set constraints on your initial system. If you have a mineral/species in your reactants pane, the components forming them should be in your initial system (Basis pane) too. Where the concentration of a particular component is negligible, you can set a small positive value (e.g. 1*10^-7). The program is asking for O2 concentration as the available basis species in the default thermo dataset (thermo.tdat) is Fe++, and you are adding Hematite to the system in which the oxidation of Iron is 3+. You can either set the Eh (or pe, f O2(g), O2(aq)), or decouple Fe2+/Fe3+. If you set Eh (or pe, f O2(g), O2(aq)) and leave Fe2+/Fe3+ coupled then the equilibrium between Fe2+/Fe3+ is determined by that Eh value. However, if you decouple Fe2+/Fe3+, then the redox equilibrium between them is set by constraining each component separately (Fe2+ and Fe3+). In this case, the system Eh has no effect on Fe speciation. If you decouple the pair and only specify Fe3+, then no Fe3+ species will form (similarly decoupling the pair and only constraining Fe2+ will prevent Fe3+ from forming), so be careful with this. To get what you are looking for, you need a titration model. I would suggest that you start with a dilute water that is in equilibrium with the atmosphere, and add Fly Ash minerals ( Lime, Mullite, Hematite, Anhydrite) as simple reactants to the system. Or, you can add them as kinetic minerals. Hope this helps. Bests, Melika Sharifi Aqueous Solutions LLC
  9. Dear M.Scharrer, Please attach your Tact and Act2 scripts here, so we can look into your problem. Thanks, Melika Sharifi Aqueous Solutions LLC
  10. Dear Pavan, I am not really familiar with Fly Ash system, but I think the way you have set your model is not representative of your system. You may need to rethink about it and see if you would need to add some minerals to your system. You can consider adding minerals as kinetic minerals. Could you, please, tell me how or based on what type of analysis you set up your system (i.e O2(aq) concentration, pH, etc.)? Thanks, Melika Sharifi Aqueous Solutions LLC
  11. Hi Pavan, Thanks for attaching your script. We received your thermo dataset, too. We will look into your script, and will get back to you here. Bests, Melika Sharifi Aqueous Solutions LLC
  12. Dear M.Scharrer, The GWB apps will only load reactions for species whose thermo data span the temperature range of the simulation. You may have thermo data for a large number of species at 25°C in Act simulation, but data for some of those species may be unavailable within temperature range set for Tact, let’s say 200 °C. In this case, Act2 simulation at 25°C, load more species than Tact simulation with temperature range from 25-200°C. You can check your simulated environment, i.e. loaded species and reactions Log ks, by going to the “view results” from the "Plot" pane of Act2 and Tact. You might wish to use the extrapolate option (Configà Alter Log Ks…à check extrapolate option), which causes apps to use the temperature polynomial to estimate log Ks outside the range of known values, to load the entire set of species over your temperature range of interest. Finally, comparing diagrams with different axes may be a bit confusing as all the parameters should be the same to give you a meaningful result. If you have any specific script for which you are not getting meaningful results considering the points mentioned above, please attach it here, and we would be happy to take a look at it. Bests, Melika Sharifi Aqueous Solutions LLC
  13. Dear Amin, In any GWB app, only basis species of the loaded thermo dataset are available to add to the basis pane using "Add”. Each thermodynamic dataset contains a number of redox coupling reactions that link species of differing oxidation states (e.g. HCO3 - and Formaldehyed). The GWB apps, by default, assume redox equilibrium in the system. When you believe your system is not in redox equilibrium, or when you have data for the same element in multiple redox states, you should decouple redox pairs by selecting Config –> Redox Couples from any GWB app. For more information, please read section 2.4 Redox Couples of the GWB Essentials Guide. Bests, Melika Sharifi Aqueous Solutions LLC
  14. Dear Amin, Several thermodynamic datasets are installed with the software, and you can load each into any GWB app using File-->Open-->Thermo Data... . One in particular called thermo.com.V8.R6+.tdat, released by Lawrence Livermore National Lab, contains a large number of organic species, including Formaldehyed. If you can’t find a particular species, it’s a simple matter to add the necessary reactions and log Ks to the GWB thermo datasets. I think you will find TEdit app very useful for making these modifications. Sections 9.2.3 and 9.2.4 in the GWB Essentials Guide describe how to add reactions to your thermo dataset using TEdit. Bests, Melika Sharifi Aqueous Solutions LLC
  15. Dear Pavan, Thanks for attaching your script and sending your thermo dataset. We looked into your script, and found a few problems with the way it is set up: 1. Act2 diagrams show the predominance of aqueous species and stability of minerals for the “diagram species” you choose in the “Basis” pane on activity and fugacity axes. In the “in the presence of” field, you choose the ligands that are in equilibrium with the system and may make complexes with the diagram species, but every field in the diagram needs to be formed from the "diagram species". For example, if you choose Al+++ as the basis species, as you did in your script, only species with Al will be shown on the plot (i.e. there is no Al in quartz, and you won’t be able to see that on the plot). You should choose either Al or H4SiO4 as the “diagram species” and then swap in the mineral of interest for that species (e.g. Gibbsite for Al, or Montmorillonite for H4SiO4). Whichever you did not choose as the “diagram species”, you can add to your system as “in the presence of field” considering it is in equilibrium with your system all over the plot. 2. On “axes” field, you can choose activity ratio of the cations present (e.g. Na+/Mg++) in the system or Eh/pH depending on what you are looking for. 3. Looking at your thermo dataset, we noticed that there are three basis species for Si (SiO2(aq), H4SiO4(aq), and H4SiO4). You need to choose one of them, and make all reaction in your dataset in terms of that one. Bests, Melika Sharifi Aqueous Solutions LLC
  16. Hi Pavan, You can use support@gwb.com to either e-mail it or share it with us. Bests, Melika Sharifi Aqueous Solutions LLC
  17. Dear Pavan, Please, attach your custom thermo dataset so we can take a look at your Act2 script. Thanks, Melika Sharifi Aqueous Solutions LLC
  18. Dear M.Scharrer, I took a look at your script and think there might be a problem with the log Ks for one of the minerals in the dataset you’re using. The Saponite(SapCa) mineral appears to be unusually stable. I first looked at the initial state of your system (Go -> Initial) with the “dump” and “flow-through” options off. You can see the results as a .txt file from “View Results” in the “Results” pane of React. The first block of results shows the metastable equilibrium state of your system (i.e., in which aqueous species are in equilibrium with each other but minerals can be oversaturated) and the second one shows the true equilibrium state of your initial system (i.e., the oversaturated minerals can precipitate). If you look at the first block of data, you would see an unusually large saturation index (log Q/K) for Saponite(SapCa). Looking at the second block of data, precipitation of the mineral leaves the fluid with 0.00 moles of Aluminum. A small dissolved concentration might be expected, but not so small that it’s rounded to 0 by the software. Since Saponite(SapCa) is the only Al mineral in your system, we took a look at the thermo dataset you’re using and noticed the very large negative log K values for that mineral. I think they’re causing too much Aluminum to be removed from the fluid. To solve this problem, I would recommend that you check the reference to verify the log Ks assigned to Saponite(SapCa), or that you simply suppress that mineral from your calculation (using the “suppress” command or by going to Config -> Suppress) if you don’t think it’s a likely phase anyway. We also noticed that there is an unreadable character in your thermo dataset that you need to address. If you open your dataset with a text editor app, you can see that at the end of line 19868 (Parmentier M., Corvisier J., Chiquet P., Parra T. et Sterpenich J. 2011. La mode) there is a non-ASCII character. Bests, Melika Sharifi Aqueous Solutions LLC
  19. Dear M.Scharrer, Thanks for bringing the error to our attention. We are looking into your problem, and will post a response here as soon as possible. Thanks, Melika Sharifi Aqueous Solutions LLC
  20. Dear Michael, To trace your mixing reaction path or to precipitate minerals you will need React app. However, you can use GSS app to see the results of mixing (volumetrically or gravimetyrically) two or more water samples in any portion. To do so, go to Analysis --> Mix Samples. At the final step in Smart Mix, save the mixture as a sample and it will appear on the GSS as a new sample. Now that you have the mixture as a sample in the GSS, you can calculate the saturation state of minerals for your mixture sample by going to Data --> Calculate. For more information, please see section 3.4.4 Mixing Samples in the GWB Essentials Guide and the tutorial titled "How do I mix samples in GSS". Bests, Melika Sharifi Aqueous Solutions LLC
  21. Dear Ao, Each thermo dataset in the GWB has a set of basis species, redox species, aqueous species, minerals, oxides, and gases. In Act2 or any other apps in the GWB software, only basis species of the loaded thermo dataset are directly available on the pulldown list. You can alter the basis species to reflect the geochemical constraints in your system by clicking the pulldown next to the species and choosing the aqueous species of your interest. And if you can not find the aqueous species of your interest in the database and are interested in adding new aqueous species/reactions along with their log Ks to each thermo dataset, you can use TEdit program which is a thermo data editor. Sections 9.2.3 and 9.2.4 in the GWB Essentials Guide describe how to add reactions to your thermo dataset using TEdit. Hope this helps. Bests, Melika Aqueous Solutions LLC
  22. Dear Amin, SpecE8 app helps you check the equilibrium state of your multicomponent system. You can calculate the saturation state of minerals or the speciation of the corrosion inhibitors in your system using SpecE8, which is included in the GWB Student Edition, but to simulate the reaction process between HCl and corrosion inhibitors you will need React, which is included in the GWB Standard package. I think you will find section 7.1 Example calculation and 7.2 Equilibrium models in the GWB Essentials Guide, and Chapter 2, Getting Started with React, and Chapter 3, Tracing Reaction paths in the GWB Standard Guide helpful. You can access the guides from the Help menu of any GWB app. In regard to your other question, you can use TEdit program, which you can access from the Support pane of the GWB Dashboard, to check the basis species and reactions along with their log Ks at different temperatures included in each thermo dataset. Best Regards, Melika Sharifi Aqueous Solutions LLC
  23. Hi Pavan, Thanks for your message. We looked into your script, and noticed a few problems with the way it is set up: 1. In the basis pane of React, you set your initial system, and in the Reactants pane you define the process that alters it (i.e. the reaction path) 2. In the Basis pane, you need to enter your actual water analysis and not the stoichiometric numbers from Montmorillonite reaction. (e.g. concentration of elements/species in your initial system). 3. Finally, if you are interested in knowing the Log Ks for Montmorillonite reaction, you can use Rxn app which calculates a reaction’s equilibrium constant at a temperature of interest. Hope this helps. Bests, Melika Sharifi Aqueous Solutions LLC
  24. You're welcome! Glad to hear you are all set. Melika
  25. Dear Frank, You can definitely use .txt files to load scatter data into the Gtplot. Using GSS, though, is the preferred way and will save you some time and make things easier for you. To work with .txt files, your file needs to be in a format readable by Gtplot. You need to prepare a table of the data using a text editor software tool (e.g. Notepad) with the first line containing the name of columns (e.g. pH, Eh, molality (Na+), etc.) and subsequent lines containing the numeric data. For example, if you are looking at sorption of Np++++ as a function of pH and have some scatter data points for pH and sorbed fraction Np++++, your table should have columns named as "pH" and "Xsorbed(Np++++)". You may also choose a special symbol, the symbol color’s and point size by adding any of the following to the data line in question: the symbol name, color, and point size. For more information on how to label your columns, please read “Scatter Data Appendix” in the GWB Reference manual that can be accessed from the Support pane of the GWB Dashboard. Best Regards, Melika Sharifi Aqueous Solutions LLC
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