Environmentally benign

The terms green chemistry and environmentally benign synthesis have been coined to refer to procedures explicitly designed to minimize the for mation of byproducts that present disposal problems Both the National Science Foundation and the Envi ronmental Protection Agency have allocated a por tion of their grant budgets to encourage efforts m this vein... 

There is a curious irony in the nomination of hypochlorite as an environmentally benign oxidizing agent It comes at a time of increasing pressure to eliminate chlorine and chlorine containing com pounds from the environment to as great a degree as possible Any all inclusive assault on chlorine needs to... 

Work on other routes to ceUulosic fibers continues, driven by a desire to identify an environmentally benign route to ceUulosic fibers that can utilize the large capital investment in the xanthate route and hence cost less than a completely new fiber process. 

As CFG refrigerants are phased out of production, their replacements in the cold storage appHcations will be HFC candidates such as R-134a, R-404A, and R-507. The use of ammonia, which is considered an environmentally benign refrigerant, will continue to play an ever-increasing role. 

Zeolite-Based All lation. Zeohtes have the obvious advantages of being noncorrosive and environmentally benign. They have been extensively researched as catalysts for ethylbenzene synthesis. Eadier efforts were unsuccessful because the catalysts did not have sufficient selectivity and activity and were susceptible to rapid coke formation and deactivation. 

With respect to the formation of unwanted polyaromatic hydrocarbons in the pyrolytic process, it has been shown that conditions can be maintained where such fonuation is negligible according to EPA and OSHA standards. As production rates are increased, it will be incumbent on any manufacturer to maintain a set of operating parameters which produce an environmentally-benign product however, current information regarding the process for fiber formation reveals no barriers to accomplishing this. 

Source reduction includes any in-plant actions to reduce the quantity or the toxicity of the waste at the source. Examples include equipment modification, design and operational changes of the process, reformulation or redesign of products, substitution of raw materials, and use of environmentally benign chemical reactions. 

An important element of pollution prevention is the selection of environmentally benign chemical reactions, raw materials, solvents, and products. Over the past few years, significant progress has been made in this area. This chapter provides a brief overview of the recent advances in synthesizing green reactions and species. For more detailed discussion, the reader is referred to Anastas and lliamson (1996), Anastas and Farris (1994), and Chase (1995). 

For a given desired product, there are typically numerous reaction alternatives that should be identified and screened. The identification of these reactions is not a straightforward task. The problem is further compounded when the search is limited to environmentally benign cost-effective chemistry. In this context, the following questions should be answered ... 

CHAPTER TWELVE Environmentally benign chemistry and species... 

Environmentally benign hydrogen is clearly the ideal fuel for use with fuel cells. The question is whether to store the hydrogen nn-bnard or to generate it on board from liquid fuels that are easier to store and distribute. 

Restructuring will promote the introduction of other advanced technologies and practices as well. For example, the use of combined-cycle, gas turbine power plants are expected to proliferate under restructuring. These plants are generally more efficient and more environmentally benign than many fossil fuel plants currently in use. 

Illman, D. Environmentally Benign Chemistry Aims for Processes That Don t Pollute, Chemical and Engineering News, Sept. 5, 1994,... 

In conclusion, the above summary of oxidation methods shows that there is still room for further improvements in the field of selective olefin epoxidation. The development of active and selective catalysts capable of oxidizing a broad range of olefin substrates with aqueous hydrogen peroxide as terminal oxidant in inexpensive and environmentally benign solvents remains a continuing challenge. 

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