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Kaushik Mitra

GWB Student
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About Kaushik Mitra

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  • Birthday 04/05/1991

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    Indian Institute of Technology, Kharagpur
  1. Kaushik Mitra

    Eh-pH Diagrams with different main ions

    Hi Katelyn, Thank you for the constant help and the demo version for my professor. I am currently working on React and would soon buy a professional license package. GWB is wonderful. I have a trifle problem regarding using React. I am trying to see the different mineral assemblages being precipitated when seawater reacts with Basalt. For the same, I have specified the composition of seawater using different ions and set water 1kg in the Basis pane. On the reactants pane I have specified the different minerals by weight %. Now I would like to change the water:rock ratio, which now i guess is 1:1, to different ratios like 10:1, 100:1 and so on. How can I do it? Thanks again for your immense support. Kaushik
  2. Hello, I am currently working on modeling the precipitation of seawater under evaporation. I am particularly concerned with the Iron containing phases. Which thermodynamic database should I choose to get a reliable result? "HMW" could have been an excellent choice except that it does not contain Fe. The other databases that are present include Fe as well as use B-dot equations. Generally B-dot is valid for Ionic Strengths less than 3 molal , but there were erroneous results (pg 132) cited in the book "Geochemical and Biochemical Reaction Modeling" by Craig Bethke. I am very perplexed with the choice of database. Please suggest a solution. Thank you
  3. Kaushik Mitra

    Eh-pH Diagrams with different main ions

    Hi Katelyn, Thank you for the solution. I knew about "Degree of Dissociation" but clearly forgot it while applying. I then understand that the "Mineral Species" that show up on the Eh-pH diagram is only telling us about the "Thermodynamic Stability" and nothing about the "Saturation" of the same and so with the Aqueous species. Whether the particular species will be precipitated in the solution or it will remain in aqueous phase will be governed with the SATURATION INDEX of the species in the solution. If I understand correctly, we cannot decide about a mineral's solubility in an Eh-pH diagram. Is it correct what I understand? I also have a huge number of sample concentration whose Activity Diagrams I need to plot. Is there a simpler way to input all the solutions at once and plot the Activity diagrams? Thank you
  4. Kaushik Mitra

    Eh-pH Diagrams with different main ions

    Hi Katelyn, Thank you so much for your reply. I was contemplating on your reply and my problem statement. I would highly appreciate if you can help me with understanding the working of GWB. Below is the crux of the problem statement and my doubts: Problem statement: I am taking the general composition of sea-water and trying to find the Eh-pH diagram for the above composition with Fe and Ca as the diagram species. Problems/Doubts: 1. The input asked by GWB Act2 are ACTIVITIES (effective concentration), rather than concentrations which values we have. Do I directly provide the concentrations and the software itself takes into account the activity calculations or I need to calculate the activities separately and then provide the same? If I have to calculate the activities, then how can I calculate the activities of the individual components? 2. When I am plotting the Eh-pH diagram, what does the BLUE shade and the YELLOW shade imply? If BLUE implies Aqueous fields and Yellow implies Mineral fields, what is the implication of species like FeSO4 or FeSO4(+) in aqueous regions? I am not able to understand how FeSO4 can exist as a molecule in aqueous field. Probably it should dissociate into Fe and SO4(-2). If not then what is the significance of FeSO4 or FeSO4(+) in aqueous field? Thank you so much
  5. Hello, I am trying to figure out the stability field of a mineral (Jarosite). When I try to plot the Eh-pH diagram with the "diagram species" as Fe(+2), I am not getting Jarosite, but with the same composition with a different diagram species such as K+ or SO4(-2) I am getting Jarosite stability fields. Why is it ? What are the implications of using different diagram species in Act2? Thank you P.S. Attached are the the Eh-pH diagrams