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Batch reaction experiment for CO2
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Topic: Batch reaction experiment for CO2 (Read 993 times)
serhatttt
Frequent Contributor
Posts: 23
Batch reaction experiment for CO2
«
on:
December 12, 2023, 10:28:25 PM »
Hi Everyone,
I am doing a batch reaction experiment. My aim is to compare changes in pH with respect to CO2 concentration for high saline geothermal water. Also, I will measure pH values after the reactor experiment and compare pH values with experimental data.
I assign gas volume and pressure, but after running the code, pH values are not reasonable.
Can you help me with this?
Thank you.
Here is the code.
SOLUTION 1
temp 25
pH 7 charge
pe 4
redox pe
units mmol/kgw
density 1
Cl 1008.57
Na 769.56
-water 1 # kg
END
USE SOLUTION 1
REACTION 1
CO2(g) 1
0.065 moles in 100 steps
GAS_PHASE 1
-fixed_pressure
-pressure 6.95 #atm
-fixed_volume
-volume 0.3557 #liter V=m*R*T/P
-temperature 25
CO2(g) 0
H2O(g) 0
REACTION_TEMPERATURE
188
USER_GRAPH 1
-headings RXN Gas_volume pH
-axis_titles "CO2 addition, mol" "Gas volume, L" "pH"
10 GRAPH_X RXN
20 GRAPH_Y GAS_VM * GAS("CO2(g)")
30 GRAPH_SY -LA("H+")
END
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dlparkhurst
Global Moderator
Posts: 3802
Re: Batch reaction experiment for CO2
«
Reply #1 on:
December 12, 2023, 11:27:52 PM »
Look at your output for the initial solution.
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serhatttt
Frequent Contributor
Posts: 23
Re: Batch reaction experiment for CO2
«
Reply #2 on:
December 13, 2023, 06:45:30 AM »
Hi David,
Thank you so much for your quick reply.
I checked my output file, but the ph values are still not reasonable. They are at around 3.7
Also, I looked at the graphs; pH values seem to be 0.8 in the y2 axis.
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dlparkhurst
Global Moderator
Posts: 3802
Re: Batch reaction experiment for CO2
«
Reply #3 on:
December 13, 2023, 03:21:43 PM »
You are charge balancing your initial solution with pH, which results in a pH less than 1 to start your calculation. Because Cl > Na in your initial solution, to charge balance, H+ is added by lowering the pH.
Set the initial solution to a pH that fits your conceptual model, and either don't charge balance or charge balance on another element.
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serhatttt
Frequent Contributor
Posts: 23
Re: Batch reaction experiment for CO2
«
Reply #4 on:
December 14, 2023, 08:36:29 AM »
Thank you so much! Now it works.
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Batch reaction experiment for CO2