Conceptual Models > Kinetics and rate controlling factors

Help Needed: Pyrite Not Dissolving Under Given Conditions in PHREEQC

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gmgmgm:
Dear all. I?m currently attempting to simulate the dissolution rate of pyrite under specific solution conditions. However, it seems that the pyrite does not dissolve with my current settings. I would greatly appreciate any insights or suggestions you might have regarding the possible reasons.
Thank you in advance!

--- Code: ---SOLUTION 1
    temp      25
    pH        2
    pe        0.85
    redox     pe
    units     mmol/kgw
    density   1
    O(0)      0.003715352
    S(6)      2.88403150
    Cl        0.00000010         
    Fe(2)     1.737800829
    Fe(3)     0.26915348
    -water    1 # kg

KINETICS 1
Pyrite
    -formula  pyrite  1
    -m        1
    -m0       1
    -parms    0.3 0.67 0.5 -0.11
    -tol      1e-08
-steps       1 in 1 steps # seconds
-step_divide 1
-runge_kutta 3
-bad_step_max 500

USER_GRAPH 1
    -headings               time Delta(Pyrite)
    -axis_titles            "Time, seconds" "Delta, moles" ""
    -initial_solutions      false
    -connect_simulations    true
    -plot_concentration_vs  x
  -start
10 GRAPH_X TOTAL_TIME
20 GRAPH_Y LOG10(-KIN_DELTA("Pyrite")/TOTAL_TIME)
  -end
    -active                 true
--- End code ---

dlparkhurst:
The Fe(2) in your system consumes all of the O2(aq), which results in a very small rate for pyrite dissolution. The MOL("O2") term makes the rate so small.

gmgmgm:
Thank you so much for that. I made such a rookie mistake.

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