# Re: PHREEQC

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I don't know if you can do what you want or not. I can tell you what the
program will accept, and then you can try to figure out whether you can
make meaningful calculations.

The main problem with your input file is that each component in the solid
solution must be defined as a PHASE. You can not nest solid solutions 1, 2,
and 3, in SOLID_SOLUTION 4. Thus you either have to define your solid
solution in terms of the fundamental component CaO, Fe(OH)2, Al2O3, SiO2,
etc. and you would probably have to combine CaO from all of the different
places with a single coefficient. Or you have to define PHASES that have
specified concentrations, which then participate in the solid solution, for
example (CaO)3(SiO2)2(H2O)3. You would have to define a reaction and an
equilibrium constant for each of these phases. I think the second approach
is probably closer to what you need to do.

The following input file uses a simplified version of your input file and
the first approach. The file simply reacts the solid solution to
equilibrium with the solution. I suspect that defining  the H2O for the
solid solution in this way is problematic; it tends to put all of the water
from the solution into the solid solution and makes a concentrated acetate
solution. Anyway, perhaps this will get you started and you can write back
with your next problem. I'm not promising the program will work for your
system, but we can give it at try.

David

TITLE Kinetic of leaching of Pb from cement

SOLUTION_MASTER_SPECIES
Ac    Ac-   0.0          60.00                         60.00
Cd(2) Cd+2  0.0          112.4
Pb(2) Pb+2  0.0          207.19
Si    H4SiO4      0.0          SiO2                    28.0843
Ca    Ca+2  0.0          Ca                      40.08
SOLUTION_SPECIES
#Acetic acid
Ac- = Ac-
log_k   0.0;                -gamma  1e7   0.0
Ac- + H2O = HAc + OH-
log_k   4.75;               -gamma  1e7   0.0
Pb+2 = Pb+2
log_k   0.0;                -gamma  1e7   0.0
Pb+2 + H2O = Pb(OH)+ + H+
log_k   -7.71;              -gamma  1e7   0.0
Pb+2 + 2H2O = Pb(OH)2 + 2H+
log_k   -17.12;             -gamma  1e7   0.0
Pb+2 + 3H2O = Pb(OH)3- + 3H+
log_k   -28.06;             -gamma  1e7   0.0
2Pb+2 + H2O = Pb2(OH)+3 + H+
log_k   -6.36;              -gamma  1e7   0.0
4Pb+2 + 4H2O = Pb4(OH)4+4 + 4H+
log_k   -20.88;             -gamma  1e7   0.0
6Pb+2 + 8H2O = Pb6(OH)8+4 + 8H+
log_k   -43.61;             -gamma  1e7   0.0
#Silicate species
H4SiO4 + H2O = H3SiO4- + H+ + H2O
log_k   -9.9;               -gamma  1e7   0.0
H3SiO4- + H2O = H2SiO4-2 + H+ + H2O
log_k   -9.9;               -gamma  1e7   0.0
CO2 + 2H2O = HCO3- + H+ + H2O
log_k   -13.31;             -gamma  1e7   0.0
HCO3- + H2O = CO3-2 + H+ + H2O
log_k   -6.4;               -gamma  1e7   0.0
END

PHASES
Ca(OH)2
Ca(OH)2 = Ca+2 + 2OH-
log_k   -5.3
Pb(OH)2
Pb(OH)2 = Pb+2 + 2OH-
log_k   -19.84
Al(OH)3
Al(OH)3 = Al+3 + 3OH-
log_k   -33.52
Fe(OH)3
Fe(OH)3 = Fe+3 + 3OH-
log_k   -38.55
Mg(OH)2
Mg(OH)2 = Mg+2 + 2OH-
log_k   -11.2
CaCO3
CaCO3 = Ca+2 + CO3-2
log_k        -10.3
SiO2
SiO2 + 2 H2O = H4SiO4
log_k        -2.71
delta_h  3.340 kcal
-analytic          -0.26             0.0         -731.0
Chalcedony
SiO2 + 2 H2O = H4SiO4
log_k        -3.55
delta_h  4.720 kcal
-analytic          -0.09             0.0         -1032.0
Quartz
SiO2 + 2 H2O = H4SiO4
log_k        -3.98
delta_h  5.990 kcal
-analytic          0.41        0.0         -1309.0
H2O
H2O = OH- + H+
log_k        -14.0
delta_h 13.362           kcal
-analytic   -283.971    -0.05069842 13323.0     102.24447   -1119669.0
CaO
CaO + H2O = Ca+2 + 2OH-
log_k        -4
Al2O3
Al2O3 + 3H2O = 2Al+3 + 6OH-
log_k        -4
Fe2O3
Fe2O3 + 3H2O = 2Fe+3 + 6OH-
log_k        -4
END
SOLUTION 0 #0.1 mol/L Acetic acid
units mol/l
pH  2.88
Ac  0.1
#SOLID_SOLUTIONS 1
#     CaO(x)SiO2(y)H2O(1-x-y)
#     -comp CaO   3
#     -comp SiO2  2
#     -comp H2O   3
#SOLID_SOLUTIONS 2
#     CaO(x)Al2O3(y)H2O(1-x-y)
#     -comp CaO   4
#     -comp Al2O3 1
#     -comp H2O   1
#SOLID_SOLUTIONS 3
#     CaO(x)Al2O3(y)Fe2O3(z)H2O(1-x-y-z)
#     -comp CaO   4
#     -comp Al2O3 1
#     -comp Fe2O3 1
#     -comp H2O   1

SOLID_SOLUTIONS 4 Cement containing Pb
CementPb
-comp Pb(OH)2           2.3
-comp Ca(OH)2           4.97
-comp Al(OH)3           0.04
-comp Fe(OH)3           0.03
-comp Mg(OH)2           0.02
#     -comp CaO(x)SiO2(y)H2O(1-x-y)             1.42
-comp CaO         4.26    # 3*1.42
-comp SiO2        2.84    # 2*1.42
-comp H2O         4.26    # 3*1.42
#     -comp CaO(x)Al2O3(y)H2O(1-x-y)            0.22
#     -comp CaO(x)Al2O3(y)Fe2O3(z)H2O(1-x-y-z)  0.10
#     -comp Calciumcarbonate              0
END

David Parkhurst (dlpark@xxxxxxxx)
U.S. Geological Survey
Box 25046, MS 413
Denver Federal Center
Denver, CO 80225

Project web page: https://wwwbrr.cr.usgs.gov/projects/GWC_coupled

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• References:

Complete Water Resources Division Software