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From: Michael R. Schock Subject: Need help with diagram I have just recently acquired GWB 3.2 and am really looking forward to applying it to our various drinking water chemical treatment studies. I have run into a snag with a diagram I would like to make, and I think I am probably missing something basic because of my inexperience. My ultimate goal is to construct a solubility vs. Eh diagram for Pb (or copper), at different pH's and for a given total carbonate concentration. I'll do multiple diagrams for different total carbonate concentrations later. I have tried using Act2 with the thermo.com.v8.r6.dat database, to which I have (I think correctly) added some aqueous species and modified some stability constants of Pb solids and complexes to make them consistent with several prior publications and modeling efforts I've done. I can get a line for Pb(II) activity, which starts flat (hydrocerussite or cerussite control) and then drops off dramatically as it passes the Eh about where I'd expect Pb(IV) to start forming and platternite to take over as the solubility control. However, I haven't been able to be positive I'm getting the solubility of Pb, and I don't get any subsequent line for equilibrium with plattnerite. I've expanded the scale to unreasonably low Pb(II) activities and it never flattens out, even at the very low concentrations I'd expect. From: Michael R. Schock Subject: Need Diagram Help At Craig's suggestion, I am reposting this help request, with a file attached that is the ACT2 script I am using that is generating this problem and question. I have just recently acquired GWB 3.2 and am really looking forward to applying it to our various drinking water chemical treatment studies. It should be extremely useful. I have run into a snag with a diagram I would like to make, and I think I am probably missing something basic because of my inexperience. My ultimate goal is to construct a solubility vs. Eh diagram for Pb (or copper), at different pH's and for a given total inorganic carbonate concentration. I'll do multiple diagrams for different total carbonate concentrations later. I have run the attached Act2 script with the original LLNL thermo.com.v8.r6.dat database, as furnished with GWB. Later, I hope to add some aqueous species and modified some stability constants of Pb solids and complexes to make them consistent with several prior publications and modeling efforts I've done, but I want to get the fundamental diagram process working first. When the attached script is run, here are the problems I'm running into. For the initial conditions I set the pH to 8, the inorganic C concentration to 18 mg/L as C (local tap water concentration), decoupled C so there aren't organic reaction complications (when I saved the script it saved it as the individual decouple commands), and set HCO3- to speciate across pH for when I do other pH's. I also disallowed several Pb solids and Pb(g) that are not viable for drinking water conditions. I have tried other pH's, and the controlling Pb(II) solid and Pb(II) aqueous species seem to change as expected, but not total Pb solubility. (1) I can get a line for Pb(II) activity, which starts flat (hydrocerussite or cerussite control) and then drops off dramatically as it passes the Eh about where I'd expect Pb(IV) to start forming and platternite to take over as the solubility control. This makes sense. (2) However, I can't find a way to produce a line for Pb(IV) activity when it would be controlled by the solubility of plattnerite. I've expanded the scale to unreasonably low Pb(II) activities and it never flattens out, even at the very low concentrations I'd expect. (3) Would it be possible to alter such a diagram for ionic strength effects? Could one of you experienced users show me where I've gone wrong, or give me an example of how to set up this kind of problem? I can't really find a comparable example in either the User's Guide or the green book. Is it not possible to do such a diagram with Act2? Or should it be set up somehow in REACT, and then somehow plotted with Gtplot or some other plotting program?

From: Finch, Robert J. Subject: Act2 mosaic plot Following the example in the GWB users' manual (v. 3.0, p.44), I diagramed As(OH)4- (with activity of As(OH)4- fixed) and SO4-- speciated over X-Y. The resulting diagram is as it is shown in the manual. But when I diagram SO4-- over the same ranges and speciate As(OH)4- over X-Y (specifying the same activities for SO4-- and As(OH)4- as for the first diagram), the stability fields shown for the solids are different. Specifically, the orpiment field is much reduced compared with the first diagram. My intuition tells me that the stability fields for the solids should be the same in both diagrams. Am I missing something? From: Craig Bethke Subject: Re: Act2 mosaic plot Perhaps this is why you seldom hear the expression "geochemist's intuition"! Seriously, although what you say seems at first glance like it might make sense, you have constructed two very different diagrams: one describes the reaction of As in a system containing S at known chemical potential, and the other reaction of S in a system containing As. To see why the diagrams differ, consider the reaction between Orpiment (As2S3) and Realgar (AsS), which appears on both plots. The reactions are: Plot 1: As2S3 + H2O <=> 2 AsS + H2S(aq) + 1/2 O2(aq) Plot 2: As2S3 + As(OH)3 <=> 3 AsS + 3/2 H2O + 3/4 O2(aq) As you can see, one reaction is balanced on As and the other on S. They have differing reaction coefficients and log K's, and hence appear in on the diagram in different positions. Remember that Act2 diagrams need never be a mystery: just set "reactions = on" and all of the reactions considered in constructing the plot are written into Act2_output.txt, which you can view with any editor or browser.

From: William F. McKenzie Subject: Act2 Axes Variables I would like to make an activity diagram for the K2O-Al2O3-SiO2-H2SO4 system; e.g., considering the phases K-feldspar, Pyrophyllite and Alunite; balancing on Al+++; fixing a[siO2(aq)] with Amorphous Silica solubility; and plotting log a(K+)/a(H+) vs log [a(SO4--)][a(H+^2)]. However, I am unable to swap SO4--*H+^2 for SO4--, trying the following: Act2> swap SO4--*H+^2 for SO4-- -- Species H+^2 is not a known basis species Act2> swap SO4--*H+*H+ for SO4-- -- Species SO4-- can only be swapped in for: SO4-- Act2> swap H+^2*SO4-- for SO4-- -- Don't know species H+^2 Act2> swap H+*H+*SO4-- for SO4-- -- Swap species H+ is already in the basis Is there a trick that I have overlooked? From: Craig Bethke Subject: Re: Act2 Axes Variables The GWB doesn't recognize the “*� syntax for an activity product. Instead, you use the “/� syntax for an activity ratio, using a negative exponent: swap SO4--/H+^-2 for SO4--

From: John Pareizs Subject: diagramming nepheline I am looking for advice and guidance on using Act2 for activity diagrams. I am running into swapping problems. My solution is basically Na+ and NO3- with a pH around 12. My x-axis is SiO2(aq), and y is Al(OH)4-/H+. I am interested in Nepheline (among others). I have tried diagramming two ways getting two results. Which is “right�? Diagram 1 swap Al(OH)4-/H+ for Al+++ swap Nepheline for H+ specify Na+ and NO3- activities with values from React output Diagram 2 swap Al(OH)4-/H+ for Al+++ swap Nepheline for Na+ specify NO3- activity from react output specify pH=12 One other question is what does the Act2 diagram command do? For example, what is the difference (or why is there a difference) between “diagram Nepheline on....� and diagram Na+ on...�, with all other things equal? From: Craig Bethke Subject: Re: diagramming nepheline I can't really answer your first question since you don't describe what problem you are trying to solve or give complete information about “Diagram 1� and “Diagram 2�. As a stab, you might be trying to understand the stability among sodic aluminosilicates as a function of silica and alumina activities in solution at pH 12. In that case, try something like: T = 300 swap Nepheline for Na+ swap Al(OH)4- for Al+++ diagram Nepheline on SiO2(aq) vs Al(OH)4- pH = 12 X -6 0 Y -6 0 As for what the “diagram� command does, that's simpler. When you create a diagram, you are considering the reactions among all species that (1) contain the species you specify on the “diagram� command, and (2) can be made up from that species plus or minus the species on the two axes, plus or minus water, and plus or minus any coexisting species you specify. In the above example, the program considers all species and minerals that can be made up of Nepheline +/- Al(OH)4- +/- SiO2(aq) +/- H2O +/- H+.

From: Dimitri Vlassopoulos Subject: label positions in act2 Dear GWB users, Is it possible to move the predominance area labels in act2? I have noticed that the default positions sometimes are not quite in the right place especially when 2 or more relatively narrow fields are adjacent to each other. From: Craig Bethke Subject: Re: label positions in act2 Like most software, the GWB programs have little artistic judgment. To spruce up your plots, select "Edit" -> "Copy to clipboard" fromAct2, Tact, or Gtplot. Then paste the plot into an illustration program like PowerPoint or Canvas. At this point you can grab labels with the mouse and move them to their optimum positions. You can also add new labeling, colored fields behind areas of predominance, and so on to make your plot easier to read.

From: Garry Davidson Subject: mosaic diagrams in act2 Has anyone any hints on how to plot phases that require full speciation of two elements, using the MOSAIC aspect of act2? An example of a mineral that requires this is siderite...requiring speciation of S and C. From: Craig Bethke Subject: Re: mosaic diagrams in act2 There is nothing magic about a mosaic diagram: you can assemble one simply by calculating diagrams for the various ligand species you wish to consider, trimming each diagram to the limits for its ligand species, and assembling the "tiles". You could you this with scissors and tape, but more likely you'd just use an illustration program. For the example you cite, calculate a diagram for iron, speciating sulfur over x-y and carbonate over x. Calculate a second diagram as before, but replace the carbonate with methane (no need to speciate). Clip off the portion of the second diagram above the methane-carbonate bounds and paste what's left over the first diagram.

From: Greg Anderson Subject: dominant fields on log f O2 vs. pH Recently I added data on polysulfides and sulfanes to the GWB database from various sources. The concentrations of polysulfides from Giggenbach's data are considerably higher than those in the database (thermo.com.V8.R6.full) which are from Shock & Helgeson (1988), but still far below H2S(aq). While doing this, I came upon a problem: on a log f O2(g) vs. pH diagram at 25 C, using my new database, Act2 shows a stability field for the polysulfide S5--, although on a log concentration vs. log f O2(g) plot (pH 6.5) made by React, this species lies far below the dominant species (H2S(aq)). I thought the stability fields on log f O2 vs pH were dominant species only. Using the old (LLNL) database, the field does not appear, although, as I said, it has a much lower concentration. I tried to make the Act2 and React compositions the same. From: Craig Bethke Subject: Re: dominant fields on log f O2 vs. pH I looked at the calculations and at first glance they appear OK. I wonder if you remembered that since you are dealing with polymeric species you need to include the stoichiometric factor? In this case, for example, the diagram is drawn taking the activities of SO4-- and H2S(aq) to be .01, but the activity of S5-- is just 0 .002 (the stoichiometric factor is 5, since the polymer contains five sulfurs). The net effect is to increase the size of the stability field for S5-- relative to its size if we had set its activity to .01. As I remember there are two important reasons to remember the stoichiometric factor. First, if we omit it, the resulting diagram isn't in a "constant mass" plane (it really isn't anyway, in the strict sense, since activity coefficients vary from species to species). Second, without it the lines don't meet at triple points when polymeric species are considered. By the way, the quickest way to get to the bottom of questions like this is to look in the Act2_output.txt dataset. It contains all of the information used to construct the diagram. (If you set "equations = on", it will even contain all of the equilibrium lines, even those discarded.) This way, you don't ever have to think of Act2 as a "black box".

From: Paul Foellbach Subject: RXN, only aqeous species ? How can I calculate a reaction without a mineral in RXN ? I would like to calculate for example Mg(OH)2 + 2H+ = Mg++ + 2H2O, this are only aqueous species.

From: Wang Lian Subject: Molysite in Rxn I tried to look at the data of Molysite in Rxn and I got this: react Molysite Activity of ??? = 10^??? What's wrong here?

From: Wang Lian Subject: problem with unrecognized minerals in GWB I use GWB v3.0 in a NT environment. I simply let Rxn program: react U3O8(c,alph), and go... the program said: don't know about species U3O8(c,alph). But this species is surely in the database. It seems the code does not recognize any of those mineral species with (c,alph)... or (c,beta).... From: Craig Bethke Subject: Re: problem with unrecognized minerals in GWB I think the problem is that you need to enclose the mineral name in quotes, since it contains a comma. For example, the command react 'U3O8(c,alph)' should work. You can use either single or double quotes (' or ").

From: Paul Foellbach Subject: swapping in Rxn I have got a question about RXN. I am interested in the reaction of Calcite. If I give the command "react Calcite" the following reaction is given as result: Calcite = CO3-- + Ca++. If I try to swap the QUARTZ for any species that contains O or Si like CO3-- the RXN answers Rxn > swap Quartz for HCO3- -- Mineral Quartz can only be swapped in for: SiO2(aq) Can you tell me how I figure the reaction of the SILICATION: CaCO3 + SiO2 = CaSiO3 + CO2(g) ? From: Wang Lian> Subject: RE: swapping in Rxn Try the following: Rxn > react Pseudowollastonite Rxn > go Pseudowollastonite + 2*H+ = H2O + Ca++ + SiO2(aq) Rxn > swap Calcite for Ca++ Rxn > go Pseudowollastonite + H+ + HCO3- = H2O + Calcite + SiO2(aq) Rxn > swap CO2(g) for HCO3- Rxn > go Pseudowollastonite + CO2(g) = Calcite + SiO2(aq)

From: Wang Lian Subject: graphical output editing Is there a way to: (1) edit the footnote in graphical output of act2 and gtplot (react)?. The footnote is below the right end of x-axis with name and date. (2) in Tact, to plot temperature T© as x-axis? From: Craig Bethke Subject: Re: graphical output editing To edit the output of the graphics programs, copy the plot to the clipboard and paste it into a illustration program such as PowerPoint, Canvas, or Adobe Illustrator (the latter is probably the best choice), and then edit it as you would any vector graphic. Alternatively, save the image in any of the formats the GWB supports and import it to the illustration program. For the best quality plot, use the EPS format with a program that can import EPS figures as editable images (PowerPoint cannot). To make a Tact plot with T along x, import the image, rotate it 90 degrees, then flip about the horizontal (you will of course need to touch up the labeling).

From: D. Craig Cooper Subject: Thermo data on transition metal sorption to calcite,silica, and alumina I'm looking for Double Layer Method thermo data that describes Co, Cs sorption onto alumina, silica, and calcite (CaOH). Any thermo data for transition metals, group-1 metals, and group-2 metals would be useful.

From: Andrew Scott Subject: NEA Database Translation Has anyone yet translated the NEA-TDB into GWB format? If so, can you share? I am particularly interested in uranium speciation. From: Yasushi Yoshida Subject: Re: NEA Database Translation JAPAN NUCLEAR CYCLE DEVELOPMENT INSTITUTE (JNC) distributes NEA-TDB as GWB format. Some of core species data are not exactly same as NEA . It means that JNC has to satisfy comprehensiveness, so additionally some data are added from other data base (for example PHREEQE original...), but mainly NEA TDB data are included. Please download it. URL : http://migrationdb.jnc.go.jp/

From: Daniel Layton-Matthews UTD Subject: High T selenium thermodata (1) The software and version: GWB 4.0.3 (2) The program(s) in question: Act2. (3) The platform: OS X with RDC WinXP (4) The thermo dataset you are using: thermo.com.v8.r6+ I am trying to create activity-pH diagrams above 200 C which include H2Se(aq), but the thermo data sets that are included with GWB only have extrapolated data to 200 C. Does anyone have any references/information/suggestions on higher temperature Selenium thermo data?

From: Kevin Telmer Subject: Organic Ligand I am interested in adding an organic ligand to the thermodynamic database ustilized by GWB (Thermo.dat). I would like to express it simply as R for starters and then model its interactions with Fe. The actual mollecule is C23N6O8H40 I thought about adding a species to Thermo.dat as follows: RFe+ charge= 1.0 ion size= 20.0 A mole wt.= 528.3 g 2 species in reaction 1.000 R-- 1.000 Fe+++ 12.65 13.08 Questions: 1. How do I add R to the basis species? Do I need to add it as an element? Is it better to add it to the aqueous species section of Thermo.dat as the mollecule itself? 2. I have only log K values for temperatures of 0 and 25C. Is there a problem if I do not include the other 6 temperatures? From: Craig Bethke Subject: Re: Organic Ligand You can add the ligand as a basis species or -- if you know its stability relative to carbonate -- as a redox couple. You don't need to add it to the element or aqueous species lists. Add the ferric complex as an aqueous species. If you don't know the log K at a principal temperature, enter a value of 500. There's lots of information about modifying the thermo data in Appendix 3 ("Thermo Datasets") of the User's Guide.

From: Richard Laffers Subject: Arsenopyrite-missing data The datablock for Arsenopyrite in the thermo.dat dataset contains log K values as follows, -15.0049 -14.4888 -14.0906 -13.8475 -13.6831 -13.5466 -232.2766 -237.0440 The latter two seem to be incorrect, moreover, the GWB programs (RXN, REACT) ignore them. E.g. when running the attached script with RXN, it gives Log K at 250 C = -13.5743 (CAUTION -- Value extrapolated from 200 C). Am I missing something? Does anybody have correct data spanning the temperatures > 200 C? (I'm running the GWB 4.0.2) data = thermo.dat verify temperature = 250 C react Arsenopyrite swap HS- for SO4-- swap AsH3(aq) for O2(aq) go From: Craig Bethke Subject: Re: Arsenopyrite-missing data Those two log K's certainly look wrong. The GWB programs, however, ignore them because there is no data at 250C or 300C for the redox coupling reaction between As(OH)4- and AsH3(aq). The only time these log K's might come into play is a decoupled model at high temperature, which is not likely since it is common to assume redox equilibrium under such conditions. We will, nonetheless, check into this and hopefully find corrected values to include in thermo.data for the next release. (Ominously, the LLNL document that thermo.dat is based on lists the data quality for arsenopyrite as "poor".) From: Alan Welch Subject: Re: Arsenopyrite-missing data This does not directly address the subject, but you may be interested in: Nordstrom, D.K., and Archer, D.G., 2003, Arsenic Thermodynamic Data and Environmental Geochemistry, in Welch, A.H., and Stollenwerk, K.G., eds., Arsenic in Ground Water: Geochemistry and Occurrence: Norwell, Massachusetts, Kluwer Academic Publishers, p. 1-25.

From: Henry Kerfoot Subject: Thermo database - citrate species I am trying to develop a database with citrate and its complexes with H+, Ca, and other metals. I have (estimated) values for delta G and delta H of formation. I am putting 'Citrate---', 'HCitrate--' , and 'H2Citrate-' in the species list, along with other citrate complexes. However, whenever I try to read the database, the program says there is an error. Where can I find detailed instructions on the format and specific entries in the database? I have not found it in the manual for Release 3.1. I recall reading a post that noted that the entry of the specific number of species in the file needs to be changed to reflect added species, and I have done that but I cannot figure out what I am doing wrong. From: Craig Bethke Subject: Re: Thermo database - citrate species I think you will find that Appendix 3 of the User's Guide contains details of the format of the thermo data. If you have misplaced your copy, you can download one from our web site. From: Laiq Rahman Subject: Re: Thermo database - citrate species I don't have the manual to hand, but I recall that it mentions that H and O need to be the first species listed in the basis. Perhaps this is the cause?

From: T.C. Onstott Subject: Fe oxides I was reproducing some figures in a paper by Potsma and Jakobsen (1996) who used Phreeqe to model Hematite and Goethite reduction of sulfide and I noticed that the GWB data seems to differ from the Phreeqe data base with respect to the log K of these two minerals. Is this true or am I missing something here?

From: Henry Kerfoot Subject: Citrate - metal complex thermo data I am looking for thermochemical data on metal-citrate complexes. I have some data on Fe++, Fe+++, H+ (1, 2, and 3) and Mg++ complexes, but would appreciate data on others.... Does anyone have such data? From: John Washington Subject: Re: Citrate - metal complex thermo data Citrate pKas and complexation constants for citric acid with Al3+, Ba2+,Be2+, Ca2+, Cd2+, Co2+, Cu2+ Fe2+, Fe3+, Mg2+, Mn2+, Ni2+, Pb2+, Ra2+,Sr2+, UO2^2+, and Zn2+ are tabulated with references in: Ringbom, Anders. 1979. Complexation in Analytical Chemistry. Robert E. Krieger Publishing Company. Huntington, NY. 395 pp. I have not seen Krieger publications many times and don't know whether this book might be hard to find. First edition looks as if it was published by Interscience Publishers, or John Wiley & Sons (maybe related?), as volume 16 of a series called Chemical Analysis.

From: John C. Ayers Subject: Thermodynamic data for aqueous Ti species I need a number for a project my class is working on. We are trying to add aqueous Ti species to the thermo.com.v8.r6+.dat database; we are using the appendix from Leturcq et al. (2001) that includes data for aqueous Ti species from Phillips et al. (1988); however, we noticed that information is missing for the species Ti(OH)+++. If anyone has the Phillips paper (reference below; our library doesn't have it) could you please email to us the standard state Gibbs free energy of formation of TiOH+++? Leturcq, G., Advocat, T., Hart, K., Berger, G., Lacombe, J., and Bonnetier, A. (2001) Solubility study of Ti,Zr-based ceramics designed to immobilize long-lived radionuclides. American Mineralogist, 86(7/8), 871-880. Phillips, S.L., Hale, F.V., Silvester, L.F., and Siegel, M.D. (1988) Thermodynamic tables for nuclear waste isolation, an aqueous solutions database. vol 1, 181 p. Report NUREG/CR-4864, LBL-22860, SAND87-0323, Lawrence Berkeley Laboratory, Berkeley, California.

From: James Cleverley Subject: water activity & osmotic coefficients The 'h2o' blocks of the GWB datafiles are tabulated coefficients for calculating the osmotic coefficients and thence the water activity (see eqs. 7.7 and 7.8 in Bethke, 1996). I have a few questions about this data and its calculation: a) The a, b, c and d parameters tabulated in Bethke (1996) are for 25, 100 and 200oC, however in the thermo.dat datafile these values are tabulated at 25, 100 and 150oC. Which is correct? Where is the publication that contains these parameters and there derivation? c) When I calculate the osmotic coefficient at 100oC using the A parameter from Table 2 in Helgeson (1969) and the equation and a,b,c,d parameters in Bethke (1996) the answer is 1.086 which is different from the 0.935 in Helgeson's table. Why the difference?

From: Henry Kerfoot Subject: LLNL/Wateq4f Database Discrepancies I am providing more details on the potential discrepancies between the Gwb/LLNL database (included with the model) and other thermodynamic databases, such as Wateq4f. Specifically, there seem to be major discrepancies between the solubility products/formation constants forthe following compounds: FeS (troilite/pyrrhotite), AsS3 (orpiment), other metal sulfides. In addition, there is a marked difference in the suite of solution sulfide species between the GWB/EQ3/6 database and the Wateq4f database and the GWB database doesn't contain FeAsS (arsenopyrite) at all. Does anyone know the reason(s) for these differences and which are more accurate (or, likely more accurately, who the main proponents are of each database)?

From: Henry Kerfoot Subject: Wateq4f Database I am hoping to do some computations on sulfide equilibria and a friend has noted that the Wateq4f database gives results for sulfides of iron and arsenic that are different from those obtained using the EQ3/6 database. Does anyone have an EQ3/6 database available that is formatted appropriately for the Geochemists Workbench that hey could share?

From: David Heasman Subject: Ammonium Carbonate I was just wondering if anyone out there has either solubility product data or the deltaGf of ammonium carbonate (NH4)2CO3.