AkuI

Hi Thanks for this If I understood correctly, in this case it is impossible in GWB to calculate so that the initial concentrations would be as told in the input at water cell nodes. Should this be something you should consider in future updates of GWB? In the experiment there is no equilibrium with the mineral cells at time step 0 but of course this is something which will happen during long time periods. However in this case GWB gives erroneous results. Regards Aku

Hi Yes I am using 8.012 version of GWB so there is only two options in the sorbing surfaces section for ion exchange and those are to choose between eq and eq/g and to put the value in. There is no node to node editor there. I will try the other way if it is possible in v. 8.0? The other equilibrium problem I meant was that yes there is no mineral phases in node 0 but there are for example lots of Ca2+ present 0.02mol/L and other ions which can only come from the clay minerals. My configure says there should be 1E-6 of Ca2+ which means only traces and other ions too excluding Na+, Cl- and CO2 complexes with these. The original pH in the node 0 should 3.9 at zero time step like in the inlet cell so why it is different? Only place where aluminum can come from is montmorillonite in this case and there is also Al complexes present in the node 0 which does not have any minerals so only explanation I can think of is that it somehow calculates some kind of equilibrium with the clay minerals. - Aku

Hi I have two problems with my model file. I am trying to model 1d column model where there is 50ml water in both ends of the column and clay in the middle. The diffusion problem works fine. The clay in the middle has it's own water inside which calculates the ionexchange sites correctly. The water cells have only 0.1 molar NaCl in equilibrium with CO2 partial pressure of 1 bar. Both ends have inlet condition the same as the water cells. First problem is that the model assumes that every cell has ion exchanger phase. Can this be somehow changed because ion exchange is not coupled to any mineral the sameway as surface complexation file. Can it be coupled or somehow done differently only to those cells with clay? The second problem is that GWB somehow calculates equilibrium to those water cells at zero timestep with minerals in clay phase when there is supposed to be only 0.1M NaCl present. Why is that? the nodes for water are 0 and 11 and 1-10 are clay cells. Can you help me? attached are database, ionexchange and surface files and the model file. -A MX80IonEx.dat MX80Surfthermoddem.dat Testi1atmCO2.x1t Thermo_thermoddem.zip

It is a pure diffusion problem with two different waters diffusing from different ends. Anyway the water in the ends will be changed, so it is okay to use inlet with diffusion properties. I have a second question. Is there a way to model with x1t or x2t that one does not have to specify inlet fluid but just the cell fluids ?

Is it possible to make a column model with x1t or x2t, in which you have two different inlets in the ends. For example other would be 0.1M NaCl and the other 0.1M CaSO4 ? Regards Aku

Found the problem already by myself. It was due to fact that the fourth species must be already in it's own line.

Hello Can you give me an advice, what is wrong with my sorption datafile. The file is attached here. The program says that the database is corrupt and the last line read is line 66. If I take the last species below away. The datafile works fine. So the problem is with the species below but I don't know what? >(w)SiO2UO2CO3-- charge= -2.0 mole wt.= 390.121 4 species in reaction 1.000 >(w)Si(OH)2 -3.000 H+ 1.000 UO2++ 1.000 HCO3- log K= 13.1 dlogK/dT= 0.0000 The thermo data file used is exported from here. http://thermoddem.brgm.fr/recherche.asp The species in the reaction are all basis species, so I don't know what I do wrong. Regards Aku QuartzSurfThermoddem.dat

Hey Does the inlet option work so that the injected water can also change. Because in the experiment there is no injection but the water outside the bentonite will change too ? As far as I understood the injected water does not change during the modelling but retains its composition. Regards Aku

Hey I have a diffusion cell where I have 50ml of water in both ends and bentonite tablet in the middle which is separated by a sinter from the water cells. Water goes through the sinter to the bentonite but bentonite maintains its compacted form. I would like to know how you can model this diffusion problem with GWB or can you ? In X1t, there are only inlet and outlet boundaries and in X2t there is closed boundary. However if I try to do closed boundary in both ends, the calculation does not seem to start. Best way for me would be a radial column, which is in X1t with only diffusion, because the tablet is cylindrical, but I don't know if the boundary conditions will match the experiment. Could you give me some advices how I can do this kind of model? Regards Aku

Thanks for the answer, I will try what you told. The forum added some ). to the end of the lines, I fixed the questions so that the links work fine now, if you would like to check those. I need only the protonation/deprotonation reactions for montmorillonite. Thanks for the help, I got it to work and understand the program a little more again Regards Aku

I would like to know how I can make a surface complexation model for montmorillonite surface according to by Bradbury and Bayens page 9. http://les.web.psi.ch/publications/abstracts/PSI_Bericht02-10.pdf I think that the instructions in manuals are poorly done and don't include how I have to adjust the database for the complexes if I am going to change the FEOH surface database. I am using thermoddem database which can be exported to GWB from here http://thermoddem.brgm.fr/recherche.asp and is too big to be attached. The Surface database is attached here. I know I have to adjust the thermoddem database, I just don't know what are all the reactions I have to add and where that this would work. Best Regards Aku Itälä MX80Surf.dat