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  2. Jia Wang

    Kinetic of complexation and sorption model

    Hello Luis, Thank you for the clarification. The thermo databases distributed along with the GWB software contain a vast amount of thermodynamic information for minerals and aqueous species. However, when a mineral is not in the database (in your case brianite), you will have to add the mineral and its thermodynamic parameters manually. You can conveniently do so by using the TEdit application. Once you have successfully added the mineral to the database, it will be available for selecting as a reactant. Please refer to section 9.1 Getting started with Tedit and 9.2 Working with datasets of the GWB Essentials guide for more information and examples. Please post on the front page of the forum in the future. Thanks. Best regards, Jia Wang
  3. Luis C. Savanguane

    Kinetic of complexation and sorption model

    Dear Jian Wang ! Thank you very much for your orientation. For how to consider the inhibitor and catalysts on modeling, your orientation is very helpful. thank you. But for the other issue, maybe I didn't clarify well. 1. I intent to simulate a kinetic dissolution and precipitation of wood ash in water using react. The XRD of wood ash indicated the presence of Calcite, Brianite and Sylvite. Reactants pane doesn't have Brianite. So how to include this mineral (brianite) on simulation? How to add this mineral on reactants pane? Sorry for disturbing you. Sincerely Luis
  4. Jia Wang

    kinetic isotopic exchange

    Hello Peter, Apologies for the delayed response. The GWB can account for equilibrium fractionation of stable isotopes as described in the Geochemical and Biogeochemical Reaction modeling text section 19. You can use the ‘segregated’ mineral option so that only minerals precipitated and dissolved are in isotopic equilibrium of the changing system. Any mineral present at the start of the time step is unaffected. Kinetic minerals are automatically considered fully isotopically segregated since they exist outside of the equilibrium system. You can set up kinetic minerals to dissolve and precipitate using rate constants and surface area. From your brief description above, your input file setup seems to be pretty efficiently setup. If you would like someone to take a closer look, please attach the file below. The GWB does not incorporate isotope fractionation kinetically as Druhan et al., 2013. Hope this helps. Best regards, Jia Wang
  5. Jia Wang

    Pressure Simulations

    Hello AJag, Here are a couple of suggestions to help you get started. You can use the ‘sliding temperature’ path option to simulate varying temperatures in React. The sliding temperature path allows you start at an initial temperature and gradually change the temperature of your system to a final desired temperature. For more information and examples, please refer to section 3.4 ‘Polythermal reaction paths’ in the GWB Reaction Modeling User’s guide. You can't set confining pressure within GWB apps except in Act2 and Tact. All thermodynamic data in the datasets distributed with the GWB is compiled along the steam saturation curve. You can, however, set the partial pressure or fugacity of gases in your system. For more information on how to set partial pressure or fugacity of gases, please refer to section 7.5 of the GWB Essentials User's guide. You can also set up your gas partial pressure or fugacity to vary over the duration of the simulation using the 'sliding' feature. For more information, you can refer to section 3.6 of the Reaction modeling user's guide. If you wish, you can compile a thermo dataset at a pressure or temperature of interest. See the K2GWB and DBCreate references on our thermo data page for more info. Hope this helps. Best regards, Jia Wang
  6. What's the best method to simulate the scaling tendencies at varying pressures and temperature using Geochemical Workbench software?
  7. Jia Wang

    Numerical Export in P2plot

    Hello Andrew, You can select the variable to be displayed as a color map or contoured in P2plot (Xtplot as well). Then use the ‘Copy and paste as text/spreadsheet’ option to export a table of numerical values of the variable you have selected to diagram or contour. For more information, please refer to section 8.7 in the GWB Reaction modeling user's guide. Hope this helps. Jia Wang
  8. Hi, I am looking at altering logK values and how those changes fit experimental data. I would like to quantitatively assess the goodness of fit of the simulated phase diagram with the experimental data points. Is there a way to obtain the numerical/tabulated values from P2plot directly? Thank you, Andrew
  9. Jia Wang

    Kinetic of complexation and sorption model

    Hello Luis, I would suggest you start by looking at the equations for kinetic complexation in Section 4.4 of the Reaction Modeling Guide. React can trace the association and dissociation of any number of aqueous complexes, as well as surface complexes. An additional resource would be the Geochemical and Biogeochemical Reaction Modeling text that may provide details on governing equations and examples in The GWB. In particular, you may be interested in Chapter 10 Surface Complexation. You can certainly consider inhibiting and promoting species in your simulation. The addition of an inhibiting or promoting species modifies the rate law for the reaction. To enable promoting or inhibiting species, you can add species in the reactants pane for the kinetic reaction of your choice and choose the power to which this species is raised to. Specifically for inhibiting species, the power raised have a negative value. For more information, please refer to section 4.2 in the Reaction Modeling guide for more information. You can add mineral as a reactant in the Reactants pane for React, Phase2, X1t, and X2t. A mineral can be specified as a kinetic or simple mineral, where the former requires user provided rate constant and surface area constraints. A simple mineral gradually adds or removes mineral to the system and the equilibrium state is calculated at every step of the reaction. Please refer to section 3 and 4 of the Reaction Modeling guide for more information and examples. Hope this helps. Best regards, Jia Wang
  10. Brian Farrell

    potential carbonate alkalinity units typo

    Hi, Thanks for catching that. This issue has been fixed. It will be available in the next maintenance release. Regards, Brian Farrell Aqueous Solutions
  11. Silvain Rafini

    Saturation index for sulfides

    Thanks very much Brian. This is very helpful. Silvain
  12. Hi Ozan, You are welcome. Best, Jia
  13. Jia Wang

    O2 release from CaO2

    Hello C. Penna, I took a quick look at your script and it seems like you have set a combined volume for the system to be greater than 100 percent. I suggest you leave medium properties at default settings unless you are specifying a porous medium from your field site or experiment. The program will calculate the porosity and volume minerals base on your entries in the basis pane. You might also want to start at 0 for the rate constant to make sure that entries in the basis pane and the rest of the system is set up correctly before starting to add in your redox reaction. Once your initial system is set up in the way you want and is able to run without the reaction, then increase the rate constant. Additionally, I noticed that you have O2(g) fugacity fixed right now in the Reactants pane. In this case, the fixed fugacity is calculated from the initial O2(aq) concentration in your basis pane. Usually a fixed gas reactant is set for modeling systems buffered in nature by contact with a gas reservoir such as the atmosphere or in a controlled laboratory setting. If you fix the fugacity of O2(g), your O2(aq) concentration will to equilibrate with the fugacity which would not change throughout the simulation. You might want to reconsider this constraint for your system. Hope this helps. Best regards, Jia
  14. C Penna

    O2 release from CaO2

    Hi Jia, Thanks for the response. I was able to successfully add in CaO2 as a redox within the thermo dataset. And then was able to create a coherent expression in Rxn for CaO2 and H2O, however I am having issues with the React application. I have tried altering the input values and seem to keep coming up with errors, mostly stating that my "porosity of node 0 is too small". I am not sure how to proceed from here. Could you provide feedback on any issues with my parameters? Thank you, C CaO2penna.rea thermopenna.tdat
  15. Thank you very much! I will be careful about that. Best, Ozan Turkes
  16. Jia Wang

    O2 release from CaO2

    Hello C. Penna, I would suggest you add the species CaO2 as a redox species into the thermo database to start. If CaO2 species is generally unstable then you can put in sufficiently large Log K values to ensure that CaO2 is thermodynamically unstable. For more information, please refer to section 9 in the GWB Essentials Guide for adding new entries into the database. I recommend you save the database with a new file name such as ‘thermo+CaO2.tdat’ to preserve the original file. Then in the GWB application you are using for your simulation (React, X1t, X2t), use the decouple dialog to decouple CaO2. This allows you to add in CaO2 as a basis species in your basis pane. You can then specify a kinetic redox reaction and an intrinsic rate constant in the reactants pane for your system to regulate the rate at which CaO2 dissociates in your system. Additionally, you might also want to consider a custom rate law as well for your reaction. GWB defaults to a built in general rate law form but you can customize your own rate law according to observations or experimental data. For more information, please refer to Section 5 in the GWB Reaction Modeling Guide. If you have any further questions, please include your input files. Best Regards, Jia Wang
  17. Hi Ozan, You're allowed to move the software three times before requiring a reset from us. I have reset your license and you should now be able to deactivate now. I hope you enjoy using the software. Best, Jia Wang
  18. Luis C. Savanguane

    Kinetic of complexation and sorption model

    Dear all! I am Luis Savanguane, learning how to use GWB. 1. I want to know how GWB calculate pH, species concentration and mineral precipitation after get the kinetic reaction rate on kinetic of complexation and sorption model (react)? Can I get the equations to quantify species contraction and pH change? 2. How to introduce (consider) inhibitors on modeling. 3. How to add mineral as reactant ? Sincerely
  19. Hi, I am getting the error 7466 ; The return of the fulfillment is denied by the return policy because max return exceed. I would be happy if you could help with this issue. Thanks! Ozan
  20. Hello Frank, Sorry for the late response. There are several options to set heterogeneous mineral mass distribution in X1t and X2t. X1t and X2t require the initial system to be configured with a single set of basis species. Therefore, an equilibrium mineral in the initial pane must be have some mass present in every node in order for the program to equilibrate the fluid with the mineral. For this reason, you would not be able to set a zero mineral mass for an equilibrium mineral. You can, however, set a heterogenous distribution for its abundance in the initial pane. For more information, please refer to the Heterogeneity Appendix in the GWB Reactive Transport Modeling Guide. Kinetic minerals are a different story. For purely kinetic minerals (those not swapped into the basis), you can set their abundance heterogeneously on the Reactants pane. There’s no issue with setting a reactant mineral in some nodes and no mass in others. For each kinetic mineral using the built-in rate law, you can supply a specific surface area (m2/g), which gets multiplied by the current mass to calculate the surface area. This property can also be set heterogeneously. Going back to the issue of different equilibrium minerals, you could alternatively write a simple flow program that uses ChemPlugin instances to figure reaction and transport. ChemPlugin is a self-linking software object based off the GWB’s compute engine. You spawn a ChemPlugin instance for each nodal block, and there’s no requirement that each instances uses the same set of basis species, so you can configure each instance in equilibrium with different minerals. To learn more about ChemPlugin, you can visit the ChemPlugin page. Hope this helps. Best, Jia
  21. I am trying to show the reaction release of CaO2 to O2 for remediation of benzene-impacted groundwater in a system. However, I cannot find an equilibrium constant value for the reaction of CaO2. How can I go about having this reaction in GWB? What is the best way to show benzene degradation through use of added O2?
  22. Hi Frank Don't know If I understand your problem correctly. Will it help if you make a copy of the mineral in the database: e.g. calcite1 and calcite2 and then give it the different surface areas you want in the model?
  23. Brian Farrell

    Saturation index for sulfides

    Hi Silvain, The reaction for Pyrite in the LLNL dataset, thermo.tdat, is shown below: Pyrite + H2O = Fe++ + 1.75 HS- + .25 SO4-- + .25 H+ You’ll notice that the reaction is written in terms of the basis species SO4-- and the redox species HS- because the oxidation state of sulfur in pyrite is between that of SO4-- and HS-. When the reaction gets loaded into an app like Rxn, SpecE8, or GSS, though, it’s rebalanced to be in terms of the basis species only: Pyrite + H2O + 3.5 O2(aq) = Fe++ + 2 SO4-- + 2 H+ This is because each of the apps assume that redox coupling reactions are enabled by default. In any case, to be able to calculate a saturation index for a mineral like pyrite, you need a way to constrain every species in the reaction. So in addition to adding Fe++ and SO4-- to your spreadsheet, you need to add O2(aq) (or Eh or pe), as well as pH. In this case, the concentration you set for the SO4-- component should represent all the sulfur in the system. The program uses the oxidation state you supply to find the equilibrium distribution of mass between sulfate and sulfide species. You can alternatively decouple HS- from SO4-- to set up a disequilibrium model. This is done from the Config > Redox Couples dialog in Rxn and SpecE8, and from Data > Redox Couples in GSS. Alternatively, simply adding the redox species HS- to your spreadsheet triggers HS- to be decoupled from SO4--. In this case, you don’t need to supply a measure of oxidation state, but you do need to provide separate measurements for the SO4-- and HS- entries. Hope this helps, Brian Farrell Aqueous Solutions LLC
  24. Jia Wang

    How can i make the sorption isotherm?

    Hello Jeonghwan, To simulate sorption in GWB, prepare a surface dataset for the ion of interest. You can refer to section 2.5 for more information on the various sorption models in GWB Essentials Users Guide and section 9.2 for more information on how to edit or create new surface datasets. Using React, you can set up a simulation to titrated the ion of interest into a system and observe the mass of ion sorbed based on the sorption model (Kd, Freundlich, Langmuir) of your choice. Note that for the Kd and Freundlich approach, you would need to completely specify mineral mass, including both equilibrium and kinetic minerals as well as any inert volume. You can do so by setting a low concentration of the ion in interest in the basis pane and then in the Reactants pane, select ‘add’ --> ‘Simple’ --> ‘Aqueous’--> name of species. Enter the total quantity you want to titrate in through the simulation and run the simulation. Plot the amount of ions in solution vs. the total concentration of ions sorbed from your simulation. Note that mass of ions sorbed per unit of solid mass is not a unit you can select in Gtplot. To convert to mass of ions sorbed per mass of soil, I would recommend copying the total sorbed mass from each simulation and divide by the total mass of soil in excel or a similar program. You can then replot your results in the desired units Hope this helps. Best Regards, Jia
  25. Silvain Rafini

    Saturation index for sulfides

    Hi Brian I'm currently making may first steps using GWB. I'm trying to calculate mineral saturation indexes for some sulfide minerals (pyrite, sphalerite, chalcopyrite, galene) that do not appear in the default list as proposed by GSS. Equilibrium constants for the dissolution reactions of these mineral are in the thermo.tdat file (more or less the LLNL database), then I can not figure why GSS do not propose it by default. Of course, my dataset includes Zn and SO4 concentrations. Thanks for helping. Silvain
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