| One of the undesirable features of the modern day world is widespread contamination associated with the release of a large number of chemicals into the environment. In recent years there has been a tremendous amount of work done to quantify the harmful effect of these trace contaminants. Society's growing concern has led many governments to establish stricter standards for clean air and water, many of them in the ppb range. This necessitates the development of greatly improved methods for controlling the release of toxic contaminants and on designing new materials tailored to selectively remove a wide range of contaminants and permit for recovery and reuse. One technology which is extremely attractive for this purpose is the use of dry adsorbents such as activated carbons.; Activated carbons have been used for many years for both air and water purification through a physical adsorption process in the micropores. Activated carbon granules (ACG's) have been the industry standard for many years. They are used as adsorbents to purify polluted waste streams because of their low cost and because they have been determined to be the best available technology for removal of many contaminants. However, the ACG's suffer from a number of drawbacks including poor selectivity, slow kinetics, the need for expensive containment systems, less than 100% working capacity, and costly reactivation. Perhaps the most serious problem is the absence of a comprehensive understanding as to the effect of pore size and chemistry on the adsorption properties. Such knowledge would allow one to tailor activated carbons for control of specific contaminants. There is a definite need for the development of improved materials designed specifically for a wide range of environmental problems. |
