The National Academies Press

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Pages 55-71

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From page 55... ... As they begin to understand the environmental fate of various products, scientists are searching for ways to make them "greener." How can commercial products and industrial waste materials be made more environmentally benign? Read the entire page →
From page 56... ... In the troposphere, nitrogen oxides produced by the combustion of fossil fuels combine with many organic molecules under the influence of sunlight to produce urban smog. The volatile hydrocarbon isoprene, well known as a building block of synthetic rubber, is also produced naturally in forests. Read the entire page →
From page 57... ... And the chIorofluorocarbons, better known as CFCs, are inert in automobile air conditioners and home refrigerators but come apart under ultraviolet bombardment in the mid-stratosphere with devastating effect on the earth's stratospheric ozone layer. The glob ally averaged atmospheric concentration of stratospheric ozone itself is only 3 parts in 10 million, but it has played a crucial protective role in the development of all biological life through its absorption of potentially harmful short-wavelength solar ultraviolet radiation. Read the entire page →
From page 58... ... To minimize waste and polluting by-products, new kinds of chemical process schemes will have to be developed. Improved chemical separation techniques are needed to enhance efficiency and to remove residual pollutants, which in turn will require new chemical treatment methods in order to render them harmless. Read the entire page →
From page 59... ... The threat to the ozone layer posed by CFCs was correctly anticipated through fundamental studies of atmospheric chemistry, eventually leading to international agreements for phasing out the production of these otherwise useful chemicals in favor of equally functional but environmentally more compatible alternatives. On the other hand, the appearance of the ozone hole over the Antarctic came as a surprise to scientists and only subsequently was traced to previously unknown chlorine reactions occurring at the surface of nitric acid crystals in the frigid antarctic stratosphere. Read the entire page →
From page 60... ... In health effects research, for example, the fields range from molecular and cellular biology to studies of exposed populations. Deliberate exposure of humans to toxic substances is unacceptable, and so data on humans are limited; risk analysis must rely on animal studies coupled with the fundamentals of biochemistry. Read the entire page →
From page 61... ... Manufacturing with Minimal Environmental impact Discharge of waste chemicals to the air, water, or ground not only has a direct environmental impact, but also constitutes a potential waste of natur al resources. Early efforts to lessen the environmental impact of chemical processes tended to focus on the removal of harmful materials from a plant's waste stream before it was discharged into the environment. Read the entire page →
From page 62... ... Water-based release agents provide an effective substitute for solvent-based products, allowing solvent emissions to be greatly reduced in the process of "demolding" polyurethane foam. Read the entire page →
From page 63... ... For example, catalytic methods allow carbon monoxide to be oxidized at the same time that nitrogen oxides are being chemically reduced in gas turbine exhaust. Other research efforts are aimed at pilot-plant evaluation of the simultaneous removal of sulfur and nitrogen oxides from flue gas by the action of a single sorbent and without the generation of massive volumes of waste products. Read the entire page →
From page 64... ... An extensive research effort to understand the appropriate biochemical processes permitted chemists to design and synthesize another new class of surfactants, linear alky~benzene sulfonates. The similarity in molecular structure between these new compounds and the natural fatty acids of traditional soaps allowed the microorganisms to degrade the new formulations, and the similarity to the branched alky~benzene sulfonates afforded outstanding detergent performance. Read the entire page →
From page 65... ... Potent yet environmentally friendly products can be extracted from plants growing in nature. An example is azidirachtin, a powerful pesticide that can be extracted from the seeds of the neem tree, indigenous to India and certain regions of Africa. Read the entire page →
From page 66... ... Substantial savings would be achieved if the volume and complexity of nuclear waste requiring storage could be significantly reduced; this reduction would require economic separation of the radioactive components from the large volumes of other materials that accompany the nuclear waste. The hazardous chemical waste might then be disposed of separately. Read the entire page →
From page 67... ... Their efforts may lead to the design and operation of a new generation of biological waste treatment facilities. A major advance in recent years is the immobilization of such microorganisms in bioreactors, anchoring them in a reactor while they degrade waste materials. Read the entire page →
From page 68... ... Whether chemical or biological methods are employed, remediation efforts must be based on an understanding of the chemistry of natural systems. Research by chemists and chemical engineers is essential to the development of effective ways to attack this pressing national problem. Read the entire page →
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From page 55...

... As they begin to understand the environmental fate of various products, scientists are searching for ways to make them "greener." How can commercial products and industrial waste materials be made more environmentally benign?