kd.ppi

# plots the solid/solution partition coefft (Kd) for the sorption of metals by HFO as a function of pH

SPECIATION
  jobTitle                             "Kd's of trace metals in neutralized AMD (A&P, Fig 11.19)"
  calculationType                      custom
  calculationMethod                    1                             # 1 = calculate and plot
  resolution                           1                             # just one iteration of x- and y-axis variables
  selectedOutputLines                  auto                          # auto = results will be on the last line of the selected output

PLOT
  plotTitle                            "Kd's of trace metals in neutralized AMD"
  xtitle                               pH
  ytitle                               "Distribution coefficient, Kd"
  customXcolumn                        pH                            # from the out file
  lines                                KdU KdZn KdCd                 # from the out file - plot these three as lines
  extraText                            "extratextkd.dat"             # additional text on/by plot

CHEMISTRY

SELECTED_OUTPUT
  reset false
  high_precision true
USER_PUNCH
  headings pH KdU KdZn KdCd                                           # these columns of data accumulate in the out file
  -start
10 IF (STEP_NO = 0) THEN 70                                           # don't output any data for plotting for initial solution calculations
20 PUNCH -la("H+")
30 KdU = SURF("U","Hfo")/TOT("U")                                     # NB TOT("U") is total dissolved U
40 KdZn = (SURF("Zn","Hfo") + mol("ZnX2"))/TOT("Zn")                  # solid phase = adsorbed + cation exchanged
50 KdCd = (SURF("Cd","Hfo") + mol("CdX2"))/TOT("Cd")
60 PUNCH KdU,KdZn,KdCd                                                # this outputs the data to selected output and then the out file
70 END
  -end

SOLUTION 1 AMD
  -temp 10
  -units mmol/kgw
  pH     2.3                                                          # analysis from some Acid Mine Drainage
  Na     23.8
  K      0.1
  Mg     2.0
  Ca     11.6
  C      1.7e-4
  Cl     13
  P      0.08
  S(6)   52.8
  Al     6.5
  Cd     0.01
  Fe(3)  10.7
  Fe(2)  0.27
  U(6)   0.18
  Zn     1.5

SURFACE 1
  Hfo_w  2e-3 600 0.89
  Hfo_s  5e-5
  -equil 1

EXCHANGE_SPECIES
  H+ + X- = HX
  log_k  1.0
  -gamma 9.0 0.0

EXCHANGE 1
  X 50e-3
  -equil 1

REACTION 1
  NaOH 1
  105e-3 in 100 steps                                                # the number of steps controls the resolution of the plot
INCREMENTAL_REACTIONS

END