Jump to content
Geochemist's Workbench Support Forum

Greg Miller

  • Content Count

  • Joined

  • Last visited

Community Reputation

0 Neutral

About Greg Miller

  • Rank
  1. Brian, Very helpful! I think after much playing around in SpecE8 I think I have it set and working properly using absolute volumes of mineral "X" as per your suggestion. I set the molar weight of X equal to quartz for physical realism, and swap X+ for X in the input. I am using 1kg solvent and the porosity and molar mass of X to calculate the kilos of X to react with and the model converges nicely. Inputs attached, I don't think I botched any of this, but you never know. A once over of the setup as compared to my intent would be greatly appreciated. I understand the principles in flush, but I am lost in the command structure to implement it. In PHREEQC I would name and recall solutions and am getting used to how to do this in GWB. I realize I will learn by doing, and looking up the commands in the Reference. Let me see how much of a mess I can make of React now and I'll come back with questions. However, if you could send what you just described as command line it would help me flop between the GUI and Reference with a little more personal certainty.... I am picking up the solids concentration, and re-reacting with the initial fluid again and again with what you outlined? Greg thermoX - Copy.tdat.dat X1MW1421520 - Copy.sdat.dat XT1_MW142S.sp8
  2. Brian, Thank you for the prompt reply! I am stuck in the CC model, also it will handle the pH-sensitive nature of boron sorption that Langmuir isn't going to. I very much like the idea of creating my own dummy element, but I am a little stuck on the surface area/porosity issues and how they are handled in GWB. Much of this is not clear to me right now, even spending some time with the manuals and program. I probably need some more clarity using the Qtz setup before I move to the dummy element. I am probably overlooking clear guidance in the documentation, but its so much easier just to ask, sorry. I have a .gss file with all the aqueous chemistry for waters I want to -flush through the sediments using react I have a .sdat file for each set of sediments, example 43% porosity I want to flush until the boron in water value doesn't change, i.e. equilibrium Where is the best place for me to be specifying my water rock ratio in Flush if I use the qtx+dummy surface model, and the best way to do that? I see a couple of ways I could set it up, specifying .43 L of solution in GSS, and setting the .57 L of quartz somewhere else, in SpecE8, or in React, or maybe as user variable in GSS that would let me batch this...but then I get lost. If I know I am doing this water rock ratio right, I can use the CC sediment boron values to test for reasonableness. Thanks! Greg
  3. I want to model the sorption of boron on surfaces using the constant capacitance (CC) model. I am trying to use a semi-mechanistic, mainly empirical, model advanced by Sabine Goldberg that uses measured physical and chemical properties of solids to calculate Kint-boron, and K+ and K- of the surface for CC. This is a generalized composite model that assigns these properties to the geomedia as a whole bulk system. Therein lays the first problem, defining a sorbing mineral phase and the surface reactions that go with it. I am very interested in the groups’ thoughts on how to best go about this. My first thought was to just alter FeOH.sdat to reflect the right Ks, surface areas, etc. and then use it as a dummy variable. Then React would be used to simulate boron adsorption on porous media using a pretty complete water quality data set. All other reactions will be turned off. The problem lies in the generalized composite model source of Kint, K+ and K-; it’s a bulk sample parameter, not mineral specific. All of the porous media would need to be Fe(OH)3 (ppt) to use a modified FeOH.sdat. My intuition is that this approach would fall apart when I went to determine bulk concentrations of boron on the solids because of molar considerations and surface site density being defined in moles/mole-mineral. The system is a granular aquifer ~80% quartz, ~20% feldspars so my second approach has been to define the sorbing mineral as SiO2 to avoid the molar volume/mass issues and use a dummy water on the SiO2 as the reacting surface. So, the surface is SiO2-OH2, and sites SiO2-OH- and SiO2-OH3+ are formed by protonation/deprotonation, and boron on the surface is SiO2-HH3BO4-. The borate ion is not considered because the pH of the system is far below the 9.2 pKa. Using a defined mineral works in my very limited understanding of the features of GWB. Using dummy water as a fake metal oxide surface makes the charges and stoichiometry work out right (I think!) and shouldn’t blow up the math anywhere. My thinking is I will avoid the molar problems described above. Is there another approach in GWB that might work better? I have to use the CC model. I can torture PHREEQC to do this with an as yet untested CC add-in, I prefer to use GWB because all my water chemistry data is in .gss, and if this goes well, I might add in some other rxns. There are a fair number of samples to be evaluated that all will need their own .sdat file. Maybe there is a better way? See any big holes in the Qtz + dummy water surface idea? I greatly appreciate anybody’s time to think about this. I am thinking someone has done something close to this before. Greg Miller
  4. I just came back to post that I found the same thing. It goes to the working directory no matter what directory you specify, until you change the working directory. That's not so bad. Thank you for the help! Greg
  5. Brian, That helped a lot. The "Copy As" function also worked to move the image over to word. Have a great weekend! Greg
  6. Of course its a Friday afternoon.... I am having a problem with Gtplot in GWB 10.0.3. Gtplot will not save image files from Piper plots. It tells me its saving an image to the directory I indicate of the type that I want, and it does not create a file. I have tried for all image types available. I can print, but when I print to Acrobat PDF the image elements end up in the corner of the page. I’m stuck.
  • Create New...