What waste is created when you buy and consume a bottle of soda? Is the plastic bottle, which you can recycle, the only waste? What are the negative environmental effects associated with this bottle of soda? The bottle is not the only waste. When considering the effect that the bottle of soda has on the environment you must think about the process of creating the bottle of soda. What waste was created when the plastic bottle was made? What chemicals were used and how were these chemicals made? How much electricity and water was needed? What about in the making of the soda? Is that it? No, we can take this a step further. The bottle still has to be disposed. What is needed to recycle the bottle? What chemicals and waste were made? Green chemists examine the entire process used to make a product and try to improve it.

Green chemistry is practicing chemistry in a way that reduces the use or generation of hazardous substances in making products. Green chemistry also tries to reduce the amount of waste produced. The entire process is considered, including creating, manufacturing, use and disposal of the product. Green chemistry processes try to be "benign by design." In other words, they are designed to have minimal environmental impact.

Processes are not usually considered green or not green. In general we look to see if a process is greener or less green. A process may be much more green than an old process but the process probably still has some negative environmental effects.

How do green chemists decide if a chemical should be used or not? Two major factors are considered when calculating the risk of a substance: the toxicity of the substance and the exposure level of the substance. If a substance has a high toxicity, but no one is exposed to it during the process, it has low risk. Similarly, if a substance has low toxicity and people are exposed to it frequently, it still has low risk. What if a substance has medium toxicity and medium exposure? The risk is greater.

Using green chemistry principles is often beneficial in more ways than the obvious. The new processes are less harmful to the environment. Often this means that the new processes are safer for workers, less expensive, more energy efficient, and require fewer materials.

Green chemists have to be creative to try to design new processes that are less harmful. The chemists in our center, CERSP, try to follow green chemistry principles to improve process related to polymers. Often our chemists use supercritical carbon dioxide to create improvements. Try some of our activities to learn more about polymers and carbon dioxide.

One of the projects that our scientists worked on was helping to icreate the new technology used for "Hangers Dry Cleaners." Hangers dry cleans clothes using carbon dioxide instead of perchloroethylene (PERC). PERC is a very toxic substance and people are exposed to the residue any time they have clothes dry cleaned using the old method. The new process is more green. Carbon dioxide is removed from the air, used to clean the clothes, captured, cleaned and reused. The dirt from the clothes is seprated and can be disposed of safely. You can learn more about "Hangers Dry Cleaners" by visiting their web site. This is just one of the projects that our scientists have worked on. Some other projects are listed below:

• Recycling - The current process used for recycling soda bottles (PET) is very inefficient. The new method being worked on replaces a long process (several hours) with a very short process that requires much less electricity and water.
• Microchip processing - The current process for etching microchips creates a lot of waste, uses a lot of water, and uses harmful chemicals. The new process being investigated would use supercritical carbon dioxide, little water, and create less waste.
• Polymer foams and nanotubes - Research is being done in these areas to improve the process that is used to create these and find new ways to use this technology.
• Fuel cells - Fuel cells are like batteries that charge themselves. They are used in hybrid cars. The old process for making fuel cell materials uses some harmful organic solvents. The new one uses carbon dioxide instead and uses less water.

To learn more about the "Twelve Principles" of green chemistry or to find resources for green chemistry, use the left-hand menu. You can learn more about our scientists and the research listed above by reading interviews and trying related activities found at "Focus On A Scientist" located under "Meet Our Scientists".