Transcript Primary Air Pollution - Virginia K. Fox Translations

Primary Air Pollution
“Bad Stuff”
So What is
Primary Air Pollution Anyways?
DR.
KNOW
is
ASHAMED!
(and why do I care?)
Recall that Air Pollutants
are substances in the air at
such concentration as to
produce a harmful effect to
humans, animals,
vegetation, or materials.
So What is
Primary Air Pollution Anyways?
DR.
KNOW
(and why do I care?)
Air Pollutants are divided into two
separate categories:
Primary Air Pollutants
is
ASHAMED! Pollutants added directly to the
atmosphere as a result of a given process.
Secondary Air Pollutants
Pollutants formed in the air as a result of
chemical reactions.
CO
NOx
Carbon Monoxide
Nitrogen Oxides
SOx
Sulfur Oxides
Particulates
HCs Hydrocarbons
The Big Five Primary Air Pollutants
?
HC
?
SOx
So, No Cop, eH (C)Qi?CO
NOx
?
Particulates
?
The Big Five Primary Air Pollutants
:CΞO:
As we already know, Carbon
Monoxide is formed from the
incomplete combustion of
hydrocarbons in oxygendeprived environments.
Carbon Monoxide is both
toxic and undetectable to the
human senses.
Formed by 2 C(s) + O2(g)  2CO(g)
FACT: 90 percent of
all carbon monoxide
production is from
natural sources.
SO
What’s the big deal
about man made
carbon monoxide?
Man Made
CO is still a
problem!
Whereas natural sources of CO tend to be widely distributed, human production
is localized and comes in periods of high emission rates
Most of the human emission of carbon dioxide is produced in
small areas, such as downtown areas.
At rush hours, emissions are concentrated.
In areas of high man made CO concentration, there is little natural reduction of CO.
CO
CO
CO
Nitrogen fixation ability is only affected at high levels of carbon monoxide.
Plants are Happy.
Nitrogen fixation ability is only affected at high levels of carbon monoxide.
Hemoglobin, the oxygen carrier in animal blood cells, becomes
unable to carry oxygen in the presence of carbon monoxide.
Animals and humans can die of asphyxiation.
CO:
Metabolic
Poison
O2 bonds with hemoglobin to form oxyhemoglobin, which then
distributes oxygen through the body. This process is easily
reversible, so the hemoglobin can pick up more oxygen.
CO bonds with hemoglobin to form carboxyhemoglobin. This
bond, however, is much stronger than that of oxyhemoglobin, and
the reaction is hence much more difficult to reverse, thus inhibiting
the ability of the hemoglobin to carry oxygen.
CO:
Metabolic
Poison
Increasing carbon monoxide
Effects of Carbon Monoxide Poisoning
Heart beats faster
Shortness of breath
Headaches
Fatigue, drowsiness
Coma
Respiratory failure
Death
No natural venues are so packed with CO
that much more then headaches can occur.
Coma and death from CO poisoning
happens in enclosed areas.
Death from carbon monoxide can be
prevented by moving the victim from the
enclosed area into fresh air.
The reverse reaction of carbon monoxide
and hemoglobin is facilitated by the
presence of ample oxygen.
The primary man made source of carbon monoxide is
TO REDUCE
PRODUCTION:
theHOW
combustion
engine of CO
the contemporary
automobile,
The Top Three by
Methods
but the problem is complicated
the presence other
3. Investigation of new fuel burning techniques and engine
pollutants.
advancements
2. Development of new transportation technology
1.
STOP DRIVING SO MUCH!
Chemistry
of a
Cleaner Engine
Thermal Exhaust Reactor
Exhaust
2CO + O2  2 CO2
HC + O2  C2 + H2O(g)
(not an exhaustive list)
Air
Less CO, Less
Hydrocarbons
But more greenhouse
gasses
Allows usage of leaner burning engines, which minimize nitrogen oxide emissions but
have increased hydrocarbon and carbon monoxide outputs.
Chemistry
of a
Cleaner Engine
Catalytic Converters
Exhaust
Air compressor
Cooling Apparatus
Catalytic Converters have the amazing
ability to convert two pollutants to
mostly harmless substances.
Platinumbased catalyst
2 CO +2 NO 2 CO2 +N2
They have, however, added six to eight hundred dollars to the price of a
car and requires high octane, non-leaded, desulferized fuel.
Nitrogen Oxides
NOx
There are eight known oxides of nitrogen.
Some of these oxides natural, others are man made.
B
a
s
i
c
s
The stability of the N-N triple bond in elemental
nitrogen gas limits the natural production of
nitrogen oxides.
The three main Nitrogen Oxides present in the air are
Nitrous Oxide, Nitric Oxide, and Nitrogen Dioxide.
Formation: N2(g) +O2(g)  2NO(g) or N2(g) +O2(g)  2NO2(g)
Nitrogen Oxides
N2O
NO
NO2
Nitrous Oxide
Dinitrogen Oxide
Nitric Oxide
Nitrogen Monoxide
Nitrogen Oxide
+1
+2
+4
Lewis
Structure
:N=N=O:
:N=O:
:O-N=O
Properties
Colorless, non-toxic,
non-flammable gas with
slight odor.
Colorless, odorless, nonflammable, toxic gas
Toxic, reddish-brown,
non-flammable gas
with strong odor
Sources
Decomposition of
nitrogen containing
compounds in soil and
lightning.
Majority from natural
sources, twenty percent
from the oxidation of
nitrogen in automobiles.
Secondary pollutant
from nitric oxide
Nitrogen
Oxidation
Number
Odd number of electrons Odd number of electrons
B
a
s
i
c
s
Nitrogen Oxides
B
a
As with CO pollution, Human Activity produces only 10 Percent
s
of the total NOx pollution.
Most human NO emissions are NO, but this is readily converted to NO in
i
the atmosphere.
c
The majority of NO and N O pollution is natural, from decomposition of nitrogen
containing organisms, bacterial action and lightning strikes.
s
x
2
2
NOx
NOx
NOx
NOx
NOx
NOx
NOx
Localization and high emission rates, however, exacerbate the problem.
Nitrogen Oxides
Both NO and NO2 are toxic to humans and animals.
Similar effects, but NO2 is worse.
Effects of NOx are most harsh in the young
and the elderly.
- Eye and nose irritation
- Breathing difficulty, respiratory distress
- Accumulation of fluid in the
lungs (pulmonary edema)
- Death
NO or
NO2
AAHHH
(No living creatures were purposely harmed to study
these effects. Study has come from low NOx
pollution when smog is trapped near the earth)
H
e
a
l
t
h
Nitrogen Oxides
The catalytic converter and the thermal exhaust reactor discussed under CO
pollution both do very well to prevent the NOx pollution.
BUT in considering the control of NOx alone, it is important to note
that the concentration of NOx creation is dependant upon the
maximum temperature reached and the amount of oxygen gas
available.
Therefore, the engines that produce less NOx are those that have
designs that either limit the amount of oxygen present in the reaction
or recycle cooler exhaust so that the exhaust reaction is cooled.
Just Say NO to Smog
C
o
n
t
r
o
l
This family of pollutants contains the
infamous sulfur dioxide, produced in
prestigious amounts, and the lesser
produced sulfur trioxide.
T
h
e
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o
w
D
o
w
n
The vast majority of primary SOx pollution is anthropogenic
(big word meaning man made)
It is estimated that humans produce approximately 150
Million Tons of SO2 per year.
That’s about fifty pounds per person!
A large amount of SO2, however, does come as a natural
secondary pollutant.
About 200 Million Tons are produced as a natural
secondary pollutant annually.
Anthropogenic Sources
T
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Combustion of Impure
The Major Sulfur Oxide Pollutor
Coal:
Low grade coal contains as much as seven percent sulfur
impurity.
Coal is polluted with both elemental sulfur, iron pyrite (FeS2),
and organic sulfurs.
Combustion causes these sulfurs to mix with oxygen, thus
yielding Sulfur Oxides.
Essentially: S(s) + O2(g  SO2
Since sulfur is removed in the refinement of petroleum and
natural gas, they are not major sources of sulfur oxide pollution.
Anthropogenic Sources
BOO!
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Smelting Plants
Treat sulfur ores, since many ores exist as sulfides.
I thought I SMELT
somethin’ funny.
The Reaction : 2 Cu2S(s) + 3 O2(g)  2 Cu2O(s) +2 SO2
Sulfuric Acid Plants
Sulfur trioxide is produced by the oxidation of sulfur dioxide, and this
is then reacted with water to form sulfuric acid. Some of the sulfur
dioxide is released into the atmosphere rather than being properly and
fully oxidized.
As a Natural Secondary
Pollutant
T
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D
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n
In nature, decay of organic material creates hydrogen sulfide
gas. This reacts with oxygen to form sulfur dioxide.
2 H2S + 3 O2  2 SO2 + 2 H2O
It can also react with ozone:
H2S + O3  SO2 + H2O
“No Chemist ever goes undead. Being the bile of living decay is not only a
degrading state of being for them, but they know that every day they are
releasing hydrogen sulfide, which is going up into the air and producing
pollution.”
--Disowned
HealthEffects
Effects
Health
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Sulfur oxides have no particular health effect of
their own as primary pollutants, but when they mix
with water they become acid rain and acid fog, and
we well know by now that that ain’t good cool digs.
The Chemistry of
Controlling SOx pollution
T
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Purifying stuff before it’s burnt
High sulfur coal is converted to synthetic natural gas (SNG) to remove the
sulfur through gasification. Sulfur is converted to hydrogen sulfide, which
is easily removed.
S + H2  H2S
Precumbustion removal of sulfur from petroleum and natural gas
Hydrogen gas is bubbled through petroleum or natural gas so that
becomes hydrogen sulfide, and this is acidic and easily removed.
The Chemistry of
Controlling SOx pollution
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Coal Washing
A physical process by which coal is ground and washed
with water.
Iron Pyrite is dense, and sinks, thus removed easily.
Organic sulfur, however, is chemically bonded to carbon
and cannot be removed by this physical process.
The Chemistry of
Controlling SOx pollution
T
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After Burning Stuff
Limestone injection or fluidized beds
Powdered limestone, CaCO3, mixes with the coal in the
combustion.
Heat from the combustion decomposes the limestone into
calcium oxide and carbon dioxide.
Calcium oxide reacts with the SO2.
CaO + SO2  CaSO3 or 2 CaO + 2 SO2 + O2  2 CaSO4
The Chemistry of
Controlling SOx pollution
T
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Wet Scrubbers
A wet-scrubber is a cleaning device that uses a liquid, usually water, to remove
contaminants.
Wet scrubbers are used to remove calcium sulfates, calcium oxides, extra sulfur
dioxide, and particulates.
The Chemistry of
Controlling SOx pollution
T
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Wet Scrubbers
Air + Coal +
CaCO3
CO2 + SO2
+CaO + O2
CaO + H2O
Alkaline Scrubber
CO2
spray
SO2 + CO2
CaO + CO2 + SO2 + CaSO4 Slurry
Slurry
Intermission
•Pressing Questions?
•Natural Needs?
Particulates
What are they?
Particulates, also called aerosol, are solid particles or
liquid droplets suspended or carried in the air. They are
generally big enough to be seen.
Smoke and soot produced by combustion.
Dust from physical breakup of solid matter.
Asbestos from industrial plants
Metallic particles
beryllium, mercury, arsenic, lead
Particulates
And their effects on health
Unsurprisingly, most particulates invade the body of the animal
through their process of respiration.
The two genres of health effects, therefore, are
directly related to the nature of the chemicals.
BlahBlahosis is the scaring of lung tissue by small quantities of
the chemical [blahblah], thus causing respiratory difficulties and
increasing risk of cancer.
Whatever Poisoning is caused by inhalation of particulates of the
chemical [whatever], little tiny bits of a highly toxic chemicals which
either cause damage in their tiny quantities or accumulate in the
body to toxic levels.
Particulates
Asbestos and Beryllium
Cause rather unpleasant respiratory conditions.
Asbestos comes in a bunch of tiny crystals, which, when
inhaled, and fart around in the lungs indefinitely. Asbestosis
occurs: lung tissue is scarred and the lining of the lungs
thicken. As a result, one experiences shortness of breath and
is more prone to lung cancer.
Beryllium is a toxic little devil of a chemical. When it gets in
the lungs, it causes a problem called berylliosis. it inflames the
tissue, causing pneumonia-like symptoms. Like asbestosis, it
causes scarring of the lung tissue, and this in turn yields
constant shortness of breath.
Particulates
Lead and Mercury
These puppies are poison stuff.
Lead, and more specifically, lead poisoning inhibits enzyme
actions. Acute lead poisoning causes an array of problems in the
human body from abdominal pain, nausea, numbness, muscle
cramps, and brain damage.
Mercury, also a metabolic poison, causes mercury poisoning,
also known as Minamata disease. It reacts with and inhibits the
human enzyme system, thus causing nerve damage and death.
Particulates
Being that particulates are just a bunch of little chunks of stuff floating around in the air,
they are relatively easy to remove.
Gravity settling chambers have a large tank which allows the
solid dusts to settle, but this only works with large particles.
Cyclone separators are essentially large scale centrifuges. The
gas is sent through a spinning cylindrical camber. Centrifugal
force causes the particles to move to the outsides and fall to the
bottom while the gases escape from the top.
Wet scrubbers are also effective.
Baghouse filters are mentioned in the packet, but we know
nothing about them.
Particulates
Electrostatic precipitators are particularly important in the
removal the tiny particles. More than 98 percent of the particulate
matter is removed.
Gas
Solids
Hydrocarbons tend to exist as extremely
volatile liquids.
C1 to C4 are gases and C5 to C12 are liquids.
Most are produced by nature, similar to NOx and
CO pollution.
Hydrocarbons are actually very similar in their
nature as pollutants to those already mentioned.
(makes it easy, but boring to learn and teach.)
Natural Sources
Geothermal Activity
Bacterial Decomposition of Organic Matter
Trees and Plants
Anthropogenic Sources
Creation of Petroleum
Incomplete Combustion of Fuel
Incomplete Combustion of Other Stuff
Healthy Ef
fects
We are immune to aliphatic hydrocarbons unless they
are in large amounts.
eg. Methane may smell bad, but it ain’t killin’ ya
Watch out for the aromatic compounds, though. They
cause irritation of the mucous membrane and can be
fatal in large amounts.
(Dramatization)
Ha
Ha
Oh
cough
ha!
crap.
!
Aromatic
HC
HC
The Automobile Problem: A Summary
-A Problem of Numbers
The Cleaner Car
-Non-Leaded Gas
-Valves
-Different Fuel to Air Ratios
-Exhaust Recycling
-Thermal Exhaust Reactors
-Catalytic Converters
Now that you have written all of
this down, a summary of this
information is available on the
web.
http://www.geocities.com/ib_homework
Questions? Comments? Angry,
Ranting, Foaming Criticisms?
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forum will be open on the website.