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Acid mine/rock drainage
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monomethyl arsenic
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Topic: monomethyl arsenic (Read 4428 times)
Scarlet
Top Contributor
Posts: 28
monomethyl arsenic
«
on:
May 21, 2018, 11:26:01 AM »
please, I want to enter the element (monomethyl arsenic and dimethyl arsenic) on solution but I do not know how to do.
thank you
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John Mahoney
Top Contributor
Posts: 81
Re: monomethyl arsenic
«
Reply #1 on:
May 21, 2018, 09:41:10 PM »
You enter them just like any other component.
you need to define them in a SOLUTION_MASTER_SPECIES block and then put them in a SOLUTION_SPECIES block. You might want to check the formula weights. When I set this up about a year ago I also left the alkalinity factors at zero, that might need to be changed. but I would have to look into that. My feeling is that unless there are really large amounts of these compounds in your solution then they will not impact the distribution of alkalinity. If you are in low ppm concentration or less for these compounds and have reasonably high alkalinities (dominantly carbonate alkalinity) you can probably get away with 0.0 values.
SOLUTION_MASTER_SPECIES
Dmasv Dmasv- 0.0 Dmasv 136.92
Mmasv Mmasv-2 0.0 Mmasv 139.92
SOLUTION_SPECIES
Dmasv- = Dmasv-
log_k 0.0
Dmasv- + H+ = HDmasv
log_k 6.14
Mmasv-2 = Mmasv-2
log_k 0.0
Mmasv-2 + H+ = HMmasv-
log_k 8.77
Mmasv-2 + 2H+ = H2Mmasv
log_k 12.97
As these are set up above they behave as independent components. They are not linked to any other form of arsenic or even to each other. So they behave essentially as independent "elements". This is because as I set up the SMS lines, I did not define the formula weights as a type of arsenic (which would be 74.922 g/mol for the element weight for As). The reactions were taken from Lafferty and Loeppert (2005). Nor are there any type of reactions that couple these back to arsenic forms.
I also have done some PhreePlot fits for sorption onto ferrihydrite from the L and L paper (more as an exercise so far). Using the diffuse Layer model. But you did not ask about that so I decided to just answer the question.
Lafferty, B.J., and Loeppert, R.H., 2005. Methyl arsenic adsorption and desorption behavior on iron oxides. Environ. Sci. Technol. vol. 39, no. 7, p. 2020-2127.
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Scarlet
Top Contributor
Posts: 28
Re: monomethyl arsenic
«
Reply #2 on:
May 24, 2018, 01:55:03 PM »
thank you very much for your answer, I entered the database as it should.
but I do not know how to enter the value of DMA and MMA.
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John Mahoney
Top Contributor
Posts: 81
Re: monomethyl arsenic
«
Reply #3 on:
May 24, 2018, 09:37:09 PM »
You will need to add the Solution_master_species and SOLUTION_SPECIES blocks at the top of the inputfile, or in the default database.
I did not see SMS or SS blocks listed in the workspace (Left side of file) you just showed the SOLUTION block. Alternatively, if you put the Components in the selected database then they should have show up.
Then I think the Program will find them and add them to the element list in the solution block.
OR iust copy this and paste into a blank pqi file and then you should be able to use the dropdowns.
SOLUTION_MASTER_SPECIES
Dmasv Dmasv- 0.0 Dmasv 136.92
Mmasv Mmasv-2 0.0 Mmasv 139.92
SOLUTION_SPECIES
Dmasv- = Dmasv-
log_k 0.0
Dmasv- + H+ = HDmasv
log_k 6.14
Mmasv-2 = Mmasv-2
log_k 0.0
Mmasv-2 + H+ = HMmasv-
log_k 8.77
Mmasv-2 + 2H+ = H2Mmasv
log_k 12.97
SOLUTION 1
temp 25
pH 7
pe 4
redox pe
units mmol/kgw
density 1
Dmasv 0
Mmasv 0
-water 1 # kg
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Scarlet
Top Contributor
Posts: 28
Re: monomethyl arsenic
«
Reply #4 on:
June 01, 2018, 11:20:19 AM »
thank you very much Mr John,for your answer
after run,I find this result (Attach)
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John Mahoney
Top Contributor
Posts: 81
Re: monomethyl arsenic
«
Reply #5 on:
June 03, 2018, 03:30:51 AM »
Your equations do not match the ones I put on the earlier email.
you are missing this equation
Mmasv-2 = Mmasv-2
log_k 0.0
The equation above is critical to the setup as it essential defines the component
and you have two of the following reaction with different log_k values
Mmasv-2 + H+ = HMmasv-
log_k 8.77
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Scarlet
Top Contributor
Posts: 28
Re: monomethyl arsenic
«
Reply #6 on:
June 11, 2018, 01:17:48 PM »
Hello Mr John, please can I have your email?
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Scarlet
Top Contributor
Posts: 28
Re: monomethyl arsenic
«
Reply #7 on:
June 11, 2018, 01:26:42 PM »
I brought in the elements, and found the elements in the solution table.
but after I returned my results I did not find the DMA and MMA in the OUTPUT results
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John Mahoney
Top Contributor
Posts: 81
Re: monomethyl arsenic
«
Reply #8 on:
June 11, 2018, 02:58:05 PM »
my email is jmahoney@mahoneygeochem.com
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Scarlet
Top Contributor
Posts: 28
Re: monomethyl arsenic
«
Reply #9 on:
June 13, 2018, 11:42:55 AM »
Thanks Mr.John.my email is: lami.elalaoui@gmail.com
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monomethyl arsenic