H4SIO4 in llnl data

[m.gamrani]

Hello
I have a question regarding H4SIO4 which does not exist in the llnl data.base, I need to introduce this H4SIO4 because it controls the pH of my solution. in addition it is really difficult to use another data.base because I work in balance with many minerals present only on llnl.
I use the following command to introduce H4SIO4 but I don’t know where the problem is.

#SOLUTION_MASTER_SPECIES
Si H4SiO4 0 SiO2 28.0843

 
SOLUTION_SPECIES
H4SiO4 = H4SiO4
      -dw  1.10e-9
      -Vm  10.5  1.7  20  -2.7  0.1291 # supcrt + 2*H2O in a1

 

H4SiO4 = H3SiO4- + H+
      -log_k  -9.83; -delta_h 6.12 kcal
      -analytic   -302.3724   -0.050698   15669.69    108.18466   -1119669.0
      -Vm  7.94  1.0881  5.3224  -2.8240  1.4767 # supcrt + H2O in a1

H4SiO4 = H2SiO4-2 + 2 H+
      -log_k  -23.0;  -delta_h 17.6 kcal
      -analytic   -294.0184   -0.072650   11204.49    108.18466   -1119669.0

you will find below the errors I find :

ERROR: Could not reduce equation to secondary master species, H4(H2SiO4)4-4.
ERROR: Non-master species in secondary reaction, H4(H2SiO4)4-4.
ERROR: Could not reduce equation to secondary master species, H6(H2SiO4)4-2.
ERROR: Non-master species in secondary reaction, H6(H2SiO4)4-2.
ERROR: Could not reduce equation to secondary master species, HSiO3-.
ERROR: Non-master species in secondary reaction, HSiO3-.
ERROR: Could not reduce equation to secondary master species, NaHSiO3.
ERROR: Non-master species in secondary reaction, NaHSiO3.
ERROR: Could not reduce equation to secondary master species, SiF6-2.
ERROR: Non-master species in secondary reaction, SiF6-2.
ERROR: Could not reduce equation to secondary master species, SiO2.
ERROR: Non-master species in secondary reaction, SiO2.

[dlparkhurst]

llnl.dat was written using the species SiO2. It is essentially the same species as H4SiO4 without two waters of hydration. llnl.dat still has H3SiO4- and H2SiO4-2 and other polymeric Si species, so the Si system still has pH effects and buffering capacity.

H4SiO4 should not be used in llnl.dat. Most of the mineral equations in llnl.dat use SiO2 (aqueous) in the dissociation reactions. If you have mineral equations with H4SiO4(aq) that you want to add to llnl.dat, convert to SiO2 with the equation H4SiO4 = SiO2 + 2H2O, log K 0.0.

Basically, just think H4SiO4 whenever you see SiO2 (aqueous) in the distribution of species for an llnl.dat calculation, and everything will be alright.