CO2goethitecarb.ppi

SPECIATION
  Database                             wateq4f.dat 
  calculationType                      simulate                                # similar format to 'fit' but no optimization
  calculationMethod                    1
  numericTags                          <sa> = 70 \                             # tag value from the fit data file
                                       <z1> = -<z0> \                          # new definition - z0 is already defined as a fit parameter below
                                       <molCO2> = "<C4>*1e-3"                  # transformation of selected output value

FIT
  dataFile                             villalobos2000.txt                      # fit data file
  dependentVariableColumnObs           obsSorbed                               # column defined in fit data file
  dependentVariableColumnCalc          sorbedC                                 # column defined in selected output file
  fitParameterNames                    log_k z0                                # two parameters - these are the names and tag names
  fitLogParameters                     0 0                                     # 0 means no log transformation of parameter value
  fitParameterValues                   22.42933879108 0.72327162992052         # parameter values

PLOT
  plotTitle                            "Carbonate sorbed on goethite vs pH<br>(Villalobos & Leckie (2000) data & CD-MUSIC)"
  xtitle                               pH
  ytitle                               "Dissolved carbonate (\mmol/L)"

  customXcolumn                        pH                                      # name of column from out file to use as x axis

  lines                                dissC
  lineWidth                            0.4
  changeColor                          T                                       # subsets have different colors

  labelSize                            1.5
  labelEffort                          2
  labels                               "63 \mM CO<sub>2</sub>, 0.01M" \        # text strings to be used as labels in plot - used in this order
                                       "90 \mM CO<sub>2</sub>, 0.01M" \        # N.B. \m gives Greek mu (or micro)
                                       "133 \mM CO<sub>2</sub>, 0.01M" \
                                       "63 \mM CO<sub>2</sub>, 0.1M" \
                                       "90 \mM CO<sub>2</sub>, 0.1M" \
                                       "133 \mM CO<sub>2</sub>, 0.1M"

CHEMISTRY

TITLE Villalobos and Leckie JCIS 22, 3787-3802 (2000) Fig. 6(b)

include "cdmusic_Hiemstra.dat"

SURFACE_SPECIES
2Goe_uniOH-0.5 + 2H+ + CO3-2 = (Goe_uniO)2CO- + 2H2O
  log_k     <log_k>
  -cd_music  <z0>  <z1>  0 0 0

SURFACE 1
  Goe_uniOHH0.5 3.45 <sa> <mass>
    -cap    0.85  0.75
  Goe_triOH0.5  2.7
    -cd_music
    -sites_units density

PHASES
  Fix_H+
    H+ = H+
    log_k  0.0

SOLUTION 1
  Na     <Na> mol/kgw
  Cl     <Cl> mol/kgw charge

SELECTED_OUTPUT
  -high_precision TRUE
  -reset FALSE

USER_PUNCH
  -headings pH dissC totC sorbedC pCO2 Alk
   10 totC = SYS("C")
   20 sorbedC = SURF("C","Goe")*1e6/(<sa>*<mass>)
   30 dissC = tot("C")*1e6
   40 pCO2 = SI("CO2(g)")
   50 punch -la("H+"), dissC, totC, sorbedC, pCO2, Alk

 EQUILIBRIUM_PHASES 1
   Fix_H+   -<obspH>   NaOH    10.0                                  # <obspH> is from fit data file
   -force_equality true

 GAS_PHASE                                                           # no O2(g) otherwise will get oxidation to HNO3
   -fixed_volume
    N2(g)  1.0
    CO2(g) 0.0
   -volume <Vg>                                                      # <Vg> is read from the fit data file

 REACTION
   CO2 1.0
   <molCO2>                                                          # <molCO2> is defined from <C4> (see above) which is read from the fit data file

 END