CO2 On Land, Sea, Air & as a Safe Solvent
other keywords: greenhouse, ozone
by Sol Steinberg, Pres. TBGS
Reprinted from TBGS newsletter issued June 1996. Revise March
1997
Foreword
The fossil marine sediments indicate that animal life began some
500 million years ago. Up until then, only fungi, algae and
bacteria were in evidence. What fostered animal beginnings? Was
it the required balanced levels of minerals in the oceans to form
shells? Very possibly --- water samples from that Pre-Cambrian
time have about the same calcium to sodium to potassium ratio as
does protoplasm in current animal cells. Was it the concentration
of Carbon Dioxide in the waters to achieve buffer-controlled pH
and the all-important acid-alkaline stability needed to sustain
life?
Then, the tremendous concentrations of carbon dioxide from
volcanic activity led to huge forests that boosted
photosynthesis. The increased availability of free oxygen tilted
changes in the direction of oxygen-loving organisms. Add to that
the balances of oxygen and ozone in the upper atmosphere that
held back intense, sometimes destructive UV from the skies; and
the concentrations of water vapor and carbon dioxide suitable to
form the roof of the "greenhouse" and catch and retain some of
the heat rising from the surface of the Earth
Dissolving ice caps, rising seas, drowning islands, and receding
shorelines are attributed to global warming. This article will in
a small measure discuss objections to the excessive releases of
industrial chemicals and combustion products. But the factors
controlling it are many.
Bear it in mind that gaseous releases also occur from flora and
fauna, and they are distinctly non-industrial. Another
reminder--long before modern civilization made the scene, the
land masses were repeatedly submerged, and then re-emerged. Ice
belts expanded when volcanic activity filled the skies
with masses of ash and gasses, clouding incoming energy and sharply
reducing temperatures worldwide. Finally, a prime cause-and-
effect temperature relationship exists with sun spot emissions,
for even as they increase and diminish is "Global Warming"
affected.
A major "path" of CO2 release today is combustion, as of fossil fuels,
wood, etc. In order to constrain serious global warming tendencies, the
world community - upwards of 150 countries - is seeking to establish
an agreed upon goal of 15% reduction of greenhouse gasses by 2010. A
meeting has been scheduled in Kyoto, Japan for December 1997 to make this accord
official. Only with the passage of time will we be able to confirm that
this is a major cause of global warming, and from this knowledge, chart
a course for the next century, and beyond.
CO2 --- A Wondrous Compound
What is known as the carbon dioxide cycle describes the chain of
events in which CO2 from the air together with water is converted
into sugars and other carbon/organic compounds via photo-
synthesis. As the name implies, it uses as "cooking" energy
radiation from the sun. Over time, the compounds eventually break
down and ultimately reappear as CO2 and water with the release
of energy.
The "Air" Layers Enveloping Earth
A Window that Absorbs and Reflects...
In the lower atmosphere, oxygen is largely in a gaseous form as
02, or formed from two oxygen atoms. Ozone, consisting of three
oxygen atoms, 03, is a relatively unstable form of oxygen
poisonous to us. It is formed by electric discharges, by
lightning, etc. It is also formed in a roundabout manner from
nitrogen oxides present in auto exhausts, and contributes to our
smog problems.
In the the ionic layer of our outer atmosphere, there are charged
atoms and molecules moving around at high speed. UV light and
cosmic rays separate (split) 0=0 into individual O atoms some of
which collide with nearby oxygen molecules, 02, to form ozone,
O3. It is this layer that bounces back to us our radio signals.
The upper atmosphere can be regarded as a special "window" that
exhibits two screening actions on light waves, to wit:
a) Incoming: the ozone layer shields the Earth's surface by
reflecting, or absorbing, "filtering out," some of the sun's
harmful (cancer producing) UV rays.
b) Outgoing: those light waves that do get through warm the
Earth, and some heat (infrared waves) radiate upward and outward.
When this energy, that would otherwise escape into space, strikes
the upper air, the CO2, water vapor, etc., present absorb and retain
part of the heat The more CO2 and water vapor present, the
greater the degree of heat trapping, and this is called the Greenhouse
Effect. So, any increases in the outer carbon dioxide level cause
the average Earth temperatures to increase a little, glaciers to
melt (recede) a little, and melting causes oceans to rise a
little, lands bordering oceans to be submerged a little more,
etc.
What Causes Openings in the Ozone?
The discovery of "holes" in the ozone layer led to a
determination by the scientific community that certain chemical
solvents, upon evaporating and reaching the upper levels, could
very conceivably interact with the ozone shield, and cause or
contribute to breaks or openings, permitting additional UV to
strike Earth.
Chlorinated solvents such as the freons (chloro-fluoro-carbons =
CFC's), or 1-1-1 tri-chloroethane, and many others, have
traditionally been used as refrigerants, as "safer," less toxic
solvents for electronics, as degreasers. etc. But since they
could be doing damage to the ozone layer, they were
internationally "outlawed". The detectable amounts in the
atmosphere appear to have been reduced and some recent
observations show a healing of some of the openings, while others
claim a worsening
CO2 in the Seas
The oceans hold over 100 billion tons of CO2 while the air
carries about 25 billion tons. Plants are believed to take up
some 60 billion tons during the course of a year, and organic
breakdown from plants, combustion, fermentation, processings,
respiration, gas wells, etc., combined, balance out by releasing
about the same 60 billion tons per year. Since the oceans were
formed some 170 million years ago, the salt content, has remained
relatively stable. There are balancing actions:
Evaporation vs. Rainfall & Runoff
Salts washing in vs. Precipitation & Deposits
Now, as to CO2 in the water, it combines with H2O to form H2CO3.
For the non-chemist, this is a bicarbonate, and it acts as a
buffer, that helps maintain a reasonably "uniform" acid-base
balance absolutely essential to the lives of all aquatic life
forms.
CO2 becomes The Supercritical Solvent
When CO2, the colorless, odorless, non-toxic, non-flammable gas
is heated to 88 degrees F., introduced into a pressure chamber,
and subjected to pressures greater than 72.8 atmospheres, it is
converted into "supercritical" form, in that it becomes a dense
fluid. While it retains its properties as a gas, and is still
capable of penetrating porous surfaces, it now has properties of
a liquid as well, and has become capable of dissolving a
(limited) number of chemical compounds.
When the conditions are changed, as when the pressure is reduced,
it reverts to its to gaseous form, and the dissolved material
separates out. Since 1970, this non-toxic material has been used
for extracting nicotine and tar from tobacco; essential oils from
plants; processing hops; removing fat from milk... USDA has
extracted oils from soybeans, from corn, from cottonseeds at
much higher pressures - 200 to 670 atmospheres and 122 ° F.
(50 degrees C.).
Wherever liquid CO2 could be employed as a solvent in place of
the CFC's, and the other undesirables (presumed to cause holes in
the ozone), the ozone layer is safeguarded. Although the CO2
would indeed tend to increase the "greenhouse effect," that
increase would modest. But employed in the manner above, its
applications were severely limited. Carbon dioxide liquid can
only dissolve and extract relatively small molecules. In order to
dissolve larger, biological molecules, such as proteins, new
techniques were needed.
CO2 Micelle (Microemulsions) Researches
Prof. Keith Johnston, UT Austin, heads an international team
that has expanded the capabilities of CO2 to dissolve and extract
complex biological materials where before it was ineffective.
This is how he did it:
He introduced water into the system together with special
surfactants (wetting agents). Micro-emulsions (called micelles)
were formed within the supercritical CO2 liquid. As the system
took on additional water, the emulsions swelled up to the point
of looking just like water itself.
A water molecule, H20, is "bent," or tentlike in an H - O - H
configuration. It behaves as a dipole. Groups of molecules within
a body of pure water will stack, and break away, and re-associate
with others. It is always partly associated in stacks - until
driven off as steam or water vapor...
Soap molecules and detergents have a water-soluble head, and a
fat-soluble tail that connects or bridges "fatty" soils to water
in which they would otherwise not be miscible. A dispersion of
oil "droplets" in water or vice versa (like mayonnaise) will
separate unless there is present a surfactant to maintain the
emulsion. The same applies to CO2 droplets in water.
Keith Johnston's team successfully formed microemulsions of
supercritical CO2 and water (stacks) capable of dissolving bovine serum
albumin by employing a nontoxic surfactant
(ammonium-carboxylate-perfluoro-polyether.) That opened the door
to the solution of many problems hitherto found too costly, or
plainly unsolvable by previous extraction methods.
Supercritical Fluid Extractions--
Strong Attraction to Biological/Pharmaceutical Groups
Apart from the fact that some solvents are currently restricted
from release to the air, when they are used, they sometimes
"damage" and/or contaminate (hard to totally remove) the products
involved, thus adding a toxic hazard. Carbon dioxide not only
minimizes damage to proteins and enzymes, it basically avoids
toxic residues, doesn't contaminate the air, and does its job
more quickly.
Capital costs are not low. To avoid corrosion and failure, top
grades of stainless steel vessels capable of withstanding the
indicated high pressures are required, plus special seals,
packings and gaskets. In the paper industry, dioxins can be
removed while yeast and mold spores are deactivated. Toxic
organic wastes can be separated from contaminated water. Many
contaminants, pesticides, PCB's, benzenes, etc., can be removed
from soils. All of these are accomplished often with much less
energy costs, even while it is more efficient and environmentally
friendly.