hfoeh.ppi

# produces a predominance diagram for the Fe-H2O system using the hunt and track approach, Eh (V) scale
#

SPECIATION
  jobTitle                             "Fe-H2O-O2"
  calculationType                      ht1                 # the 'hunt and track' method
  calculationMethod                    1                   # 1=calculate, 2=replot, 3=resimplify and replot
  mainSpecies                          Fe                  # make a Fe diagram

  xmin                                 2.0                 # pH range (x-axis) 2-12
  xmax                                 12.0

  ymin                                 -90.0               # log f(O2(g)) range (y-axis) -90 to 0
  ymax                                 0.0
  resolution                           250                 # searching takes place over a 250 x 250 grid

PLOT
  plotTitle                            "Fe-O<sub>2</sub>-H<sub>2</sub>O<br>(only HFO precipitates: Eh (V) scale)"
  xtitle                               pH
  yscale                               Eh                  # use Eh scale (V) - default title is 'Eh (V)'
  pymin                                -1                  # min y value on plot scale
  pymajor                              0.5                 # interval between major ticks and labels on y-scale
  pdf                                  T                   # make a pdf file (assumes Ghostscript installed)

CHEMISTRY

# first simulation - initial solution calculation only calculated once

include 'ht1.inc' 

SOLUTION 1
   pH        1.8
   units     mol/kgw
   Fe(3)     1e-2                                          # total Fe in system
   Na        1e-1
   Cl        1e-1
END

# second (final) simulation - the final simulation is iterated many times as required by the hunt and track procedure
USE solution 1
EQUILIBRIUM_PHASES 1
   Fix_H+ -<x_axis> NaOH 10
     -force_equality true
   O2(g)  <y_axis>

   Fe(OH)3(a) 0 0                                          # the only mineral considered
END