P.ppi

SPECIATION
  jobTitle                             "Fe-Al-Ca-P"
  calculationType                      ht1
  calculationMethod                    1
  mainSpecies                          "P"
  xmin                                 2.0                           # x-axis calculation range
  xmax                                 10.0
  ymin                                 -80.0                         # y-axis calculation range
  ymax                                 0.0
  resolution                           500                           # tracks on a 500 x 500 grid
PLOT
  plotTitle                            "P-Fe-Al-Ca<br>(including mineral and adsorbed species)"
  xtitle                               pH
  ytitle                               "log <i>f </i>O<sub>2</sub>(g)"
  extraText                            "extratextP.dat"

CHEMISTRY

include 'ht1.inc' 

# first simulation - initial solution calculation
SOLUTION 1
   Temp      20
   pH        1.8
   units     mol/kgw
   density   1
   P         1e-3
   Ca        1e-1
   Fe        1e-1
   Al        1e-1
   Na        1e-1
   Cl        1e-1 charge
END

# second simulation - reaction and equilibration

USE solution 1

EQUILIBRIUM_PHASES 1
   Fix_H+     -<x_axis> NaOH                                         # fix the pH
    -force_equality true
   O2(g)      <y_axis>
   CO2(g)     -3.5                                                   # atmospheric PCO2(g)

    Hydroxyapatite                 0 0                               # choose the minerals you want (from the database)
#   Magnetite                      0 0
    Hematite                       0 0
    Vivianite                      0 0
#   Fe3(OH)8                       0 0
#   Goethite                       0 0
#   Fe(OH)2.7Cl.3                  0 0
#   Diaspore                       0 0
#   Gibbsite                       0 0
#   Maghemite                      0 0
#   Boehmite                       0 0
    Al(OH)3(a)                     0 0
    Fe(OH)3(a)                     0 0                               # assumed the metastable Fe-oxide mineral
    Portlandite                    0 0
    Strengite                      0 0
    Calcite                        0 0
    Siderite                       0 0

SURFACE
    Hfo_sOH Fe(OH)3(a)      equilibrium_phase 0.005  53300           # phosphate adsorbed by Hfo
    Hfo_wOH Fe(OH)3(a)      equilibrium_phase 0.2
END