Iodine Chemistry And It

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Iodine Chemistry And Its Role In Ozone Depletion

• PRESENTED BY
• Farhana Yasmin

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Introduction
Ozone depletion in the troposphere has always
been the main concern to the environment.
There are many factors, most of them coupled,
that causes the depletion of the ozone, such as
reactions and transport.
The reaction mechanism includes
tropospheric chemistry of ozone, hydrocarbon,
nitrogen as well as sulfur and the halogens Cl,
Br and I.
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Objective
Model of ozone depletion using FACIMILE that
will allow us to investigate the effect of the
iodine on ozone depletion.
Since iodine is a much more effective agent
compared to bromine and chlorine, it is
suspected that even in small amount iodine may
have a profound impact on ozone depletion.
The modeling of ozone depletion will allow us to
see the effect on the rate of ozone depletion
with iodine concentration
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OH/NOx Cycle
CO
hv H2O
OH
HO2
H2O2
DEPOSITION
HO2
HNO4
O3
OH
HNO3
NO2
NO
hv
hv
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Iodine Cycle
INO3
NO2
IO
IO
IO
HO2
HOIaq
O3
I2O2
HOI
NO
Aerosol
HI
OH
hv
I-
I
I2
hv
hv
hv
hv
hv
hv
INO2
NO2
CH3I
CH2I2
C3H7I
CH2ClI
OCEAN
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Photochemistry
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Bimolecular Reaction
Arrhenius Equation
k rate constant A Pre-exponential constant E
activation Energy R Gas constant T
Temperature in K
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Termolecular Reactions
OH NO2 M -------gt HNO3 M HO2 NO2 M
-----? HNO4 M I NO2 M -------gt INO3
M IO NO2 M -----? INO3 M
M
The low pressure-limiting rate constant
The high pressure-limiting rate constant
Effect Second Order Rate Constant
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Heterogeneous Reactions
Forward Reaction
Backward Reaction
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Effect of I and IO on Ozone Depletion
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Effect of O3 concentration on Iodine
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Effect of NOx on Ozone Depletion
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Effect of NOx on Ozone Depletion
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Conclusion

• The magnitude of catalytic ozone destruction
• depends on the amount of reactive iodine present.

• As the iodine concentration increases the ozone
  depleted faster

• I reaches steady state faster as O3
  concentration
• decreases

• O3 depletion rate increases as NOx concentration
  is decreased

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Recommendations

• Problems using FACSIMILE
• Easy to make mistake
• Does not allow to add reactions
• Order of reaction matters

• This study is highly theoretical and our
  conclusions, therefore,
• strongly need testing with observational data.

• Further identification of the marine biological
  processes leading
• to the production of organic iodine gases and
  their releases
• to the atmosphere.

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THANK YOU
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THAT'S ALL FOLKS!!!