Problem while coupling surface complexation and SIT

[mbrandely]

Hello everyone,
I would be happy to have some help on a surface complexation issue I am dealing with.

I am trying to model oxyanions (molybdenum, selenium and antimony) leaching from naturally contaminated excavated earths. Depending on the composition of the bulk material, oxyanions leaching as a function of pH seems to be more or less affected by surface complexation at natural iron oxides surface sites.
For Mo and Sb, I managed to obtain good fit of my experimental data considering kinetic dissolution for most of the mineral phases and using DDL (with or without explicit calculation of the diffuse double layer) for complexation with thermodynamic data extracted from Gustafsson J.P. (2003) and Meima and Comans (1998). However for Se, no matter which complexation data I chose among the huge diversity available, an explicit calculation of the diffuse double layer seems to be critical to reproduce experimental data in my case.

My problem is the following: because I am working on strongly carbonated earths, ionic strength of leachates (especially at acidic pH) can reach values up to 3 to 4 mol/L. Hence, to account for potential ion interactions and since a Pitzer approach is not suitable to the elements I am studying, I chose to work with a version of Thermochimie database that use Specific Ion Interaction Theory for aqueous speciation calculation. However, for some reasons that I cannot clearly explain, considering SIT and complexation with an explicit calculation of the diffuse double layer is not possible or incorrect in the way I am using it.
I am getting error messages as : "No potential unknown found for surface species Surfa_CB"

Although it is more a conceptual problem, I can attach a piece of code if needed. I'd be happy to take any of your suggestion which could help me to build a consistent model able to represent my excavated earths behavior.

Thanks
Maxime

[dlparkhurst]

Sorry, I do not think that option is available. I get the following when trying to calculate an explicit diffuse layer with sit.dat:

ERROR: -diffuse_layer option not available for Pizer or SIT model

[dlparkhurst]

Looking at the code, it looks like there have been modifications to allow DDL calculation for the Pitzer model, and a quick test to allow sit.dat seemed to work. I don't have a lot of confidence, but attach a simple input file that shows the problem, and I will take a look.

Also attach the database, if it is not the standard Thermochemie database.

[mbrandely]

Thanks a lot for your answer.

Here is one simplified version of a code I wrote as long as the version of thermochimie I used (I think it is the standard version).
Since kinetic modelling is very important in my case, I needed to explicitely define each point of the pH dependency test I was trying to model. I could not figure out better ways although I am sure there are. I hope it won't be too difficult to understand..

Code: [Select]

SOLUTION_MASTER_SPECIES
Ntg Ntg 0 Ntg 28.0134
SOLUTION_SPECIES
Ntg = Ntg # N2
-log_k  0.0

##############################################################################################################
SURFACE_MASTER_SPECIES
        Hfo_s  Hfo_sOH
        Hfo_w  Hfo_wOH
       
SURFACE_SPECIES
Hfo_wOH = Hfo_wOH
        log_k 0.0
Hfo_sOH = Hfo_sOH
        log_k 0.0

Hfo_sOH + H+ = Hfo_sOH2+
log_k 7.29
Hfo_sOH = Hfo_sO- + H+
log_k -8.93
Hfo_wOH + H+ = Hfo_wOH2+
log_k 7.29
Hfo_wOH = Hfo_wO- + H+
log_k -8.93

###############################
####        CATIONS        ####
###############################

########## Calcium ##########
#ref : phreeqc.dat
Hfo_sOH + Ca+2 = Hfo_sOHCa+2
log_k 4.97
Hfo_wOH + Ca+2 = Hfo_wOCa+ + H+
log_k -5.85

########## Magnesium ##########
#ref : phreeqc.dat
Hfo_wOH + Mg+2 = Hfo_wOMg+ + H+
log_k -4.6

########## Strontium ##########
#ref : phreeqc.dat
Hfo_sOH + Sr+2 = Hfo_sOHSr+2
log_k 5.01
Hfo_wOH + Sr+2 = Hfo_wOSr+ + H+
log_k -6.58
Hfo_wOH + Sr+2 + H2O = Hfo_wOSrOH + 2H+
log_k -17.6

###############################
####        ANIONS         ####
###############################

########## Sulfur ##########
#ref : phreeqc.dat
Hfo_sOH + SO4-2 + H+ = Hfo_sSO4- + H2O
log_k 7.78
Hfo_wOH + SO4-2 + H+ = Hfo_wSO4- + H2O
log_k 7.78
Hfo_sOH + SO4-2 = Hfo_sOHSO4-2
log_k 0.79
Hfo_wOH + SO4-2 = Hfo_wOHSO4-2
log_k 0.79

########## Antimony ##########
#ref : Meima and Comans (1998)
Hfo_sOH + Sb(OH)6- + H+ = Hfo_sSb(OH)6 + H2O
log_k 11.33
Hfo_wOH + Sb(OH)6- + H+ = Hfo_wSb(OH)6 + H2O
log_k 11.33
#Hfo_sOH + Sb(OH)6- = Hfo_sOHSb(OH)6-
# log_k 4.33
#Hfo_wOH + Sb(OH)6- = Hfo_wOHSb(OH)6-
# log_k 4.33

########## Fluor ##########
#ref : phreeqc.dat
Hfo_wOH + F- + H+ = Hfo_wF + H2O
log_k 8.7
Hfo_wOH + F- = Hfo_wOHF-
log_k 1.6

########## Carbonates ##########
# ref : Van Geen et al., 1994 reoptimized for D&M model #
Hfo_wOH + CO3-2 + H+ = Hfo_wCO3- + H2O
log_k 12.56
Hfo_wOH + CO3-2 + 2H+= Hfo_wHCO3 + H2O
log_k 20.62

########## Molybdenum ##########
# ref : Gustafsson J.P., 2003
Hfo_sOH + MoO4-2 = Hfo_sOHMoO4-2
log_k 3.14
Hfo_wOH + MoO4-2 = Hfo_wOHMoO4-2
log_k 3.14
Hfo_sOH + MoO4-2 + H2O + 2H+ = Hfo_sOMo(OH)5
log_k 17.8
Hfo_wOH + MoO4-2 + H2O + 2H+ = Hfo_wOMo(OH)5
log_k 17.8

#Sélénite (Dzombak and Morel, 1990; minteq.v4; Dijkstra et al. 2009)
Hfo_sOH + H(SeO3)- = Hfo_sSeO3- + H2O
     log_k 4.29
Hfo_sOH + H(SeO3)- = Hfo_sOHSeO3-2 + H+
     log_k -3.23
Hfo_wOH + H(SeO3)- = Hfo_wSeO3- + H2O
     log_k 4.29
Hfo_wOH + H(SeO3)- = Hfo_wOHSeO3-2 + H+
     log_k -3.23
#Selenate (Verbinen et al. 2013)
Hfo_sOH + SeO4-2 + H+ = Hfo_sOH2SeO4-
     log_k 11.7
Hfo_wOH + SeO4-2 + H+ = Hfo_wOH2SeO4-
     log_k 11.7

PHASES
Ntg(g)
Ntg = Ntg
-analytic -58.453 1.81800e-3  3199  17.909 -27460

## Dolomite written with Sr and oxyanion incorporation
CaMgSr(CO3)2
CaMg0.97Sr0.03(MoO4)0.00011(Sb(OH)6)0.0000033(SeO3)0.00001(CO3)1.9998767 + 1.9998767H+  = 1.9998767HCO3- + 1.000Ca+2 + 0.97Mg+2 + 0.03Sr+2 + 0.00011 MoO4-2 + 0.0000033 Sb(OH)6- + 0.0000033e- + 0.00001 SeO3-2
     log_k     2.754     
     delta_h  -60.916    #kJ/mol        #78hel/del,92ajoh
     -analytic -1.7923812E+3  -2.8963813E-1  9.9363286E+4  6.5115141E+2  -5.6008892E+6
     #References = LogK/DGf: Internal calculation; DHf/DHr: 78hel/del,92ajoh; S°: 78hel/del,92ajoh; Cp: 95rob/hem; V°: 78hel/del,92ajoh;
END

RATES
## By pass precipitation
Goethite
-start
10 mole = 0
20 If (m <= 0) and (SR("Goethite") < 1) Then GoTo 250
30 S = 0.1 # average BET; suggested value in m2/g
40 Mm = 106.847 # molar mass in g/mol
50 If (SR("Goethite") > 1) Then GoTo 250
########## start dissolution bloc ##########
60 knu = 1.14815E-08  * exp((-86500 / 8.314) * ((1 / TK) - (1 / 298.15)))
80 k = knu
# kinetic data extracted from 92nag/las 93nag/las 08ben/pal
90 theta = 1 # default value
100 eta = 1 # default value
110 rate = S * m * Mm *(m/m0)^0.67 * k * ((1 - SR("Goethite") ^ theta) ^ eta)
120 GoTo 240
########## end dissolution bloc ##########
########## start precipitation bloc ##########
130 knu = 1.14815E-08 * exp((-86500 / 8.314) * ((1 / TK) - (1 / 298.15)))
150 kpre = (-1) * knu
160 theta = 1
170 eta =  1
# kinetic data extracted from 92nag/las 93nag/las 08ben/pal
180 If (m <= 0) then GoTo 210
190 rate = S * m * Mm *(m/m0)^0.67 * kpre * (ABS(1 - SR("Goethite") ^ theta) ^ eta)
200 GoTo 240
#start nucleation
210 rate = -1e-10
#end nucleation
########## end precipitation bloc ##########
240 mole = rate * Time
250 Save mole
-end

SOLUTION 1
-ph 7 charge
-redox pe
-units mol/kgw
-temp 25
-water 1
#Max. leached concentration
Mo 5.5e-06 #pHnatural ANC
Sb 2e-8
Se 1.3e-6 #pH=12.9

#Leached concentrations at natural pH
Si 4e-4
K 1e-4
Al 7e-6
Na 1.7e-4
S(6) 1e-4
N(5) 1e-5
SAVE SOLUTION 1
END

EQUILIBRIUM_PHASES 1
Calcite 0 0.67 dissolve_only
CaMgSr(CO3)2 0 0.0285 #dissolve_only
Aragonite 0 0.0496 dissolve_only
Gypsum 0 0.0009 #dissolve_only

#phases autorisées à précipiter
Strontianite 0 0
Ferrihydrite(am) 0 0.0018
Gibbsite 0 0
Brucite 0 0

SAVE EQUILIBRIUM_PHASES 1
END

GAS_PHASE 1
-fixed_volume
-equilibrate with solution 1
-volume 1.5
-pressure 1.000
Ntg(g) 0.78
O2(g) 0.21
CO2(g) 0.0004
SAVE GAS_PHASE 1
END

KINETICS 1-96; Goethite; -m0 0.001; -step 259200 in 1; -tol 1e-06; -bad_step_max 1000;

SURFACE 1
Hfo_sOH Goethite kinetic_reactant 0.005 600
Hfo_wOH Goethite kinetic_reactant 0.2
#-no_edl
END

USER_PUNCH 1
-headings Density Molarity_Ca Molarity_Mg Molarity_S(6) Molarity_Sr Molarity_Si Molarity_Al Molarity_K Molarity_Na Molarity_Fe Molarity_Mo Molarity_Se Molarity_Sb Molarity_F
-start
10 REM Calcul de molarité
20 PUNCH RHO
30 m_Ca = TOT("Ca") * RHO
40 m_Mg = TOT("Mg") * RHO
50 m_S = TOT("S(6)") * RHO
60 m_Sr = TOT("Sr") * RHO
70 m_Si = TOT("Si") * RHO
80 m_Al = TOT("Al") * RHO
90 m_K = TOT("K") * RHO
100 m_Na = TOT("Na") * RHO
110 m_Fe = TOT("Fe") * RHO
120 m_Mo = TOT("Mo") * RHO
130 m_Se = TOT("Se") * RHO
140 m_Sb = TOT("Sb") * RHO
150 m_F = TOT("F") * RHO
160 PUNCH m_Ca
161 PUNCH m_Mg
162 PUNCH m_S
163 PUNCH m_Sr
164 PUNCH m_Si
165 PUNCH m_Al
166 PUNCH m_K
167 PUNCH m_Na
168 PUNCH m_Fe
169 PUNCH m_Mo
170 PUNCH m_Se
171 PUNCH m_Sb
172 PUNCH m_F
-end

SELECTED_OUTPUT
    -file                  Calcareous-sample_SIT.txt
-ionic_strength true
-reaction true
-equilibrium_phases Calcite CaMgSr(CO3)2 Strontianite Gypsum Aragonite Gibbsite Ferrihydrite(am) Brucite
-kinetic_reactants Goethite
-totals Ca Mg S(6) Sr Si Al K Na Fe Mo Se Sb F Hfo_s Hfo_w
      -molalities ### Mo ###
H2MoO4 HMoO4- MoO4-2
### Sb ###
    Sb(OH)3 Sb(OH)2+ Sb(OH)4-
Sb(OH)6- Sb(OH)5
### Se ###
HSe-
SeO3-2 H(SeO3)- H2(SeO3)
SeO4-2 H(SeO4)-

Hfo_sO- Hfo_sOH2+ Hfo_wO- Hfo_wOH2+
### Anions complexation - Hfo ###
Hfo_sOMo(OH)5 Hfo_sOHMoO4-2 Hfo_wOMo(OH)5 Hfo_wOHMoO4-2
Hfo_sSeO3- Hfo_sOHSeO3-2 Hfo_wSeO3- Hfo_wOHSeO3-2 Hfo_sOH2SeO4- Hfo_wOH2SeO4-
Hfo_sSb(OH)6 Hfo_wSb(OH)6

## ETM

USER_GRAPH 1 Mo
-headings pH tot_Mo Hfo_sOHMoO4-2 Hfo_wOHMoO4-2 Hfo_sOMo(OH)5 Hfo_wOMo(OH)5
-chart_title "Evolution of Mo"
-axis_titles "pH" "Mo (mol/L))"
#-axis_scale x_axis 0 20 1
-start
10 graph_x -la("H+")
30 graph_y TOT("Mo"), MOL("Hfo_sOHMoO4-2"), MOL("Hfo_wOHMoO4-2"), MOL("Hfo_sOMo(OH)5"), MOL("Hfo_wOMo(OH)5")
-end

USER_GRAPH 2 Se
-headings pH tot_Se Se(IV) Se(VI) Hfo_wOH2SeO4- Hfo_wSeO3- Hfo_wOHSeO3-2 pe
-chart_title "Se concentration = f(pH)"
-axis_titles "pH" "Se (mol/L))" "pe"
#-axis_scale x_axis 0 20 1
-start
10 graph_x -la("H+")
30 graph_y TOT("Se"), TOT("Se(4)"), TOT("Se(6)"), MOL("Hfo_wOH2SeO4-"), MOL("Hfo_wSeO3-"), MOL("Hfo_wOHSeO3-2")
40 graph_sy -LA("e-")
-end

USER_GRAPH 3 Sb
-headings pH tot_Sb Sb(III) Sb(V) Hfo_sSb(OH)6 Hfo_wSb(OH)6
-chart_title "Evolution of Sb"
-axis_titles "pH" "Sb (mol/L))"
#-axis_scale x_axis 0 20 1
-start
10 graph_x -la("H+")
30 graph_y TOT("Sb"), TOT("Sb(3)"), TOT("Sb(5)"), MOL("Hfo_sSb(OH)6"), MOL("Hfo_wSb(OH)6")
-end

USER_GRAPH 4 F
-headings pH tot_F Hfo_wF Hfo_wOHF-
-chart_title "Evolution of F"
-axis_titles "pH" "F (mol/L))"
#-axis_scale x_axis 0 20 1
-start
10 graph_x -la("H+")
30 graph_y LOG10(TOT("F")), MOL("Hfo_wF"), MOL("Hfo_wOHF-")
-end

USER_GRAPH 5 SO4
-headings pH SO4
-chart_title "Evolution of SO4"
-axis_titles "pH" "SO4(mol/L))"
#-axis_scale x_axis 0 20 1
-start
10 graph_x -la("H+")
30 graph_y LOG10(TOT("S(6)"))
-end

USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 85; USE SURFACE 1; REACTION 85; HNO3 1; 2.5 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 84; USE SURFACE 1; REACTION 84; HNO3 1; 2.25 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 83; USE SURFACE 1; REACTION 83; HNO3 1; 2.0 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 82; USE SURFACE 1; REACTION 82; HNO3 1; 1.99 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 81; USE SURFACE 1; REACTION 81; HNO3 1; 1.98 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 80; USE SURFACE 1; REACTION 80; HNO3 1; 1.97 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 79; USE SURFACE 1; REACTION 79; HNO3 1; 1.96 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 78; USE SURFACE 1; REACTION 78; HNO3 1; 1.95 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 77; USE SURFACE 1; REACTION 77; HNO3 1; 1.9 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 76; USE SURFACE 1; REACTION 76; HNO3 1; 1.85 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 75; USE SURFACE 1; REACTION 75; HNO3 1; 1.8 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 74; USE SURFACE 1; REACTION 74; HNO3 1; 1.79 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 73; USE SURFACE 1; REACTION 73; HNO3 1; 1.78 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 72; USE SURFACE 1; REACTION 72; HNO3 1; 1.77 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 71; USE SURFACE 1; REACTION 71; HNO3 1; 1.76 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 70; USE SURFACE 1; REACTION 70; HNO3 1; 1.75 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 69; USE SURFACE 1; REACTION 69; HNO3 1; 1.74 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 68; USE SURFACE 1; REACTION 68; HNO3 1; 1.73 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 67; USE SURFACE 1; REACTION 67; HNO3 1; 1.72 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 66; USE SURFACE 1; REACTION 66; HNO3 1; 1.71 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 65; USE SURFACE 1; REACTION 65; HNO3 1; 1.7 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 64; USE SURFACE 1; REACTION 64; HNO3 1; 1.69 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 63; USE SURFACE 1; REACTION 63; HNO3 1; 1.68 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 62; USE SURFACE 1; REACTION 62; HNO3 1; 1.67 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 61; USE SURFACE 1; REACTION 61; HNO3 1; 1.66 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 60; USE SURFACE 1; REACTION 60; HNO3 1; 1.65 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 59; USE SURFACE 1; REACTION 59; HNO3 1; 1.64 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 58; USE SURFACE 1; REACTION 58; HNO3 1; 1.63 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 57; USE SURFACE 1; REACTION 57; HNO3 1; 1.62 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 56; USE SURFACE 1; REACTION 56; HNO3 1; 1.61 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 55; USE SURFACE 1; REACTION 55; HNO3 1; 1.6 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 54; USE SURFACE 1; REACTION 54; HNO3 1; 1.59 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 53; USE SURFACE 1; REACTION 53; HNO3 1; 1.58 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 52; USE SURFACE 1; REACTION 52; HNO3 1; 1.57 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 51; USE SURFACE 1; REACTION 51; HNO3 1; 1.56 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 50; USE SURFACE 1; REACTION 50; HNO3 1; 1.55 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 49; USE SURFACE 1; REACTION 49; HNO3 1; 1.54 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 48; USE SURFACE 1; REACTION 48; HNO3 1; 1.53 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 47; USE SURFACE 1; REACTION 47; HNO3 1; 1.52 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 46; USE SURFACE 1; REACTION 46; HNO3 1; 1.51 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 45; USE SURFACE 1; REACTION 45; HNO3 1; 1.5 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 44; USE SURFACE 1; REACTION 44; HNO3 1; 1.2 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 43; USE SURFACE 1; REACTION 43; HNO3 1; 1.0 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 42; USE SURFACE 1; REACTION 42; HNO3 1; 0.8 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 41; USE SURFACE 1; REACTION 41; HNO3 1; 0.7 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 40; USE SURFACE 1; REACTION 40; HNO3 1; 0.6 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 39; USE SURFACE 1; REACTION 39; HNO3 1; 0.5 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 38; USE SURFACE 1; REACTION 38; HNO3 1; 0.4 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 37; USE SURFACE 1; REACTION 37; HNO3 1; 0.35 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 36; USE SURFACE 1; REACTION 36; HNO3 1; 0.3 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 35; USE SURFACE 1; REACTION 35; HNO3 1; 0.25 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 34; USE SURFACE 1; REACTION 34; HNO3 1; 0.2 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 33; USE SURFACE 1; REACTION 33; HNO3 1; 0.15 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 32; USE SURFACE 1; REACTION 32; HNO3 1; 0.1 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 31; USE SURFACE 1; REACTION 31; HNO3 1; 0.09 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 30; USE SURFACE 1; REACTION 30; HNO3 1; 0.08 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 29; USE SURFACE 1; REACTION 29; HNO3 1; 0.07 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 28; USE SURFACE 1; REACTION 28; HNO3 1; 0.06 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 27; USE SURFACE 1; REACTION 27; HNO3 1; 0.05 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 26; USE SURFACE 1; REACTION 26; HNO3 1; 0.04 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 25; USE SURFACE 1; REACTION 25; HNO3 1; 0.03 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 24; USE SURFACE 1; REACTION 24; HNO3 1; 0.02 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 23; USE SURFACE 1; REACTION 23; HNO3 1; 0.01 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 91; USE SURFACE 1; REACTION 91; HNO3 1; 0.005 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 92; USE SURFACE 1; REACTION 92; HNO3 1; 0.001 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 93; USE SURFACE 1; REACTION 93; HNO3 1; 0.00075 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 94; USE SURFACE 1; REACTION 94; HNO3 1; 0.0005 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 95; USE SURFACE 1; REACTION 95; HNO3 1; 0.00025 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 96; USE SURFACE 1; REACTION 96; HNO3 1; 0.0001 mole in 1 steps; END

USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 1; USE SURFACE 1; REACTION 1; NaOH 1; 0 mole in 1 steps; END

USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 86; USE SURFACE 1; REACTION 86; NaOH 1; 0.00025 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 87; USE SURFACE 1; REACTION 87; NaOH 1; 0.0005 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 88; USE SURFACE 1; REACTION 88; NaOH 1; 0.00075 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 89; USE SURFACE 1; REACTION 89; NaOH 1; 0.001 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 90; USE SURFACE 1; REACTION 90; NaOH 1; 0.005 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 2; USE SURFACE 1; REACTION 2; NaOH 1; 0.01 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 3; USE SURFACE 1; REACTION 3; NaOH 1; 0.02 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 4; USE SURFACE 1; REACTION 4; NaOH 1; 0.03 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 5; USE SURFACE 1; REACTION 5; NaOH 1; 0.04 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 6; USE SURFACE 1; REACTION 6; NaOH 1; 0.05 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 7; USE SURFACE 1; REACTION 7; NaOH 1; 0.06 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 8; USE SURFACE 1; REACTION 8; NaOH 1; 0.07 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 9; USE SURFACE 1; REACTION 9; NaOH 1; 0.08 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 10; USE SURFACE 1; REACTION 10; NaOH 1; 0.09 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 11; USE SURFACE 1; REACTION 11; NaOH 1; 0.1 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 12; USE SURFACE 1; REACTION 12; NaOH 1; 0.15 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 13; USE SURFACE 1; REACTION 13; NaOH 1; 0.2 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 14; USE SURFACE 1; REACTION 14; NaOH 1; 0.25 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 15; USE SURFACE 1; REACTION 15; NaOH 1; 0.3 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 16; USE SURFACE 1; REACTION 16; NaOH 1; 0.35 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 17; USE SURFACE 1; REACTION 17; NaOH 1; 0.4 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 18; USE SURFACE 1; REACTION 18; NaOH 1; 0.5 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 19; USE SURFACE 1; REACTION 19; NaOH 1; 0.6 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 20; USE SURFACE 1; REACTION 20; NaOH 1; 0.7 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 21; USE SURFACE 1; REACTION 21; NaOH 1; 0.8 mole in 1 steps; END
USE SOLUTION 1; USE EQUILIBRIUM_PHASES 1; USE GAS_PHASE 1; USE KINETICS 22; USE SURFACE 1; REACTION 22; NaOH 1; 1.0 mole in 1 steps; END

[dlparkhurst]

Sorry, the current code does not allow an explicit diffuse-layer calculation with SIT. What is worse is that there is a bug for the combination of SIT, surface, and some redox situations, and your calculation may fall into that category.

I will fix the bug in the next version, which may be coming out fairly soon; there are a few glitches in 3.7.0 that we need to fix. I will also enable the diffuse-layer calculation for SIT, but be warned, it has not been tested with SIT. It was developed with ion-association models, and has been extended to Pitzer, but I am not sure if it works correctly with SIT.

[mbrandely]

OK, thanks for your time.
I am looking forward to try the next version and in the meantime I will set aside the SIT since it has an influence only at extreme pH values.
Best regards