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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

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.