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Beginners => PHREEQC basics => Topic started by: frenzy_geochem on April 02, 2020, 01:00:57 PM

Title: Using H2S output Solution 1 in Solution 2
Post by: frenzy_geochem on April 02, 2020, 01:00:57 PM
Hii all,

Today, I got stuck on a little problem. I want to try and simulate how H2S(g) created from Solution 1 reacts with Solution 2. I cannot put 'USE solution 1' as I want to keep the solutions seperated. It is only the H2S(g) I want to add to Solution 2. When that has happened, I want to heat solution 2 (but I don't think that is a problem). Any ideas?

Code: [Select]
PHASES
      H2S(g)
        H2S  =  + 1.0000 H+ + 1.0000 HS-     
        log_k    -7.9759
  delta_h 1.08  kcal
      Fix_pH
        H+ = H+
        log_k 0

SOLUTION 1
-water 0.0155
temp 25
pH -0.15
Na 1.29
S(-2) 0.645
S(6) 0.71
END

EQUILIBRIUM_PHASES
Fix_pH   -7 NaOH 10

SOLUTION 2
-water 0.04
temp 25
pH 2
Fe(+3) 0.3
Cl 0.9
END

REACTION_TEMPERATURE 1
        25.0 85.0 in 12 steps

USE Solution 2
USE Reaction_temperature 1
END

Title: Re: Using H2S output Solution 1 in Solution 2
Post by: dlparkhurst on April 02, 2020, 04:16:44 PM
You haven't created any H2S(g) with solution 1. You need to use either EQUILIBRIUM_PHASES or GAS_PHASE to partition H2S(g) out of solution into a gas phase. If the gas evolves to a known partial pressure, you could use EQUILIBRIUM_PHASES. If the gas evolves into a fixed volume (or fixed pressure), you could use GAS_PHASE.

Here is one experiment where 1 L (kg water) evolves H2S(g) into 1 liter of head space.

Code: [Select]
SOLUTION 1
-water 0.0155
temp 25
pH -0.15
Na 1.29
S(-2) 0.645
S(6) 0.71
END
USE solution 1
GAS_PHASE 1
    -fixed_volume
    -pressure 1
    -volume 1
    -temperature 25
    H2S(g)    0
SAVE gas_phase 1
END
SOLUTION 2
USE gas_phase 1
END