Sustainable inherently safer processes

The welfare of the people who work with chemical products and processes is at least as important as the welfare of the environment. Green chemistry is anthropocentric (as is sustainable development). Several green chemistry principles reflect this anthropocentrism. Principles 3 (less-hazardous chemical synthesis), 4 (design of safer chemicals), 5 (safer solvents and auxiliaries), and 12 (inherently safer chemistry for accident prevention) express concern for the health of the people who handle materials or attend to processes (Anastas and Warner, 1998). While many of these safety benefits also accrue to nonhuman organisms, the focus of the principles is on the people who are exposed to these materials and methods. Inasmuch as we cannot know all of the environmental needs of nonhuman things, it is hard to imagine how the focus could be on anything else. 

Sustainable Chemistry and Inherently Safer Design 49 Table 1.9 Examples of process risk management strategies. Source adapted from Mannan [90]. 

Substitution of an hazardous chemical is often an even more complex problem, in particular regarding the trade-off between inherently safer design and sustainable chemistry. Several examples are discussed in subsequent chapters. We thus limit our discussion here to a few aspects. Up until around the 1960s the Reppe process was employed for of synthesis of acrylic esters ... 

Successfui appiication of these principles can potentially reduce the risk enough that an SIF is not required, or if an SiF is required, a lower risk reduction than SIL 4 can be used. It should be noted that there is aiways a trade-off in applying inherently safer principles one type of risk may be reduced, but another risk may increase. There may be trade-offs between yield, productivity, cost, and safety risk. These trade-offs should be evaluated from a system perspective, looking at all of the requirements for a process including environmental, health and safety, sustainable development, operational, quality, and business. 

Degradability, in particular, could be a bottleneck in designing inherently safer and sustainable ionic liquids, because the technologically high desirable tendency of certain ionic liquids to be very stable, both thermally and chemically, is often reflected by their recalcitrance towards biological degradation processes. 

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