Environmental Engineering Reference
In-Depth Information
3.1 Description of the Environmental Problem
'Green chemistry' is essentially a way of thinking rather than a new branch of
chemistry and is about utilizing a set of principles that seek to reduce the
environmental impact of chemical processes and products. It involves pulling
together tools, techniques and technologies that can help chemists and chemical
engineers in research, development and production to develop more eco-
friendly and efficient products and processes, which may also have significant
financial benefits. Green chemistry aims to improve the way that chemicals are
both produced and used in chemical processes in order to reduce any impact on
man and the environment. The promotion of green chemistry is one of the most
important ways in which chemistry and chemists can contribute to sustainable
development.
Society has many concerns about 'chemicals' and their uses. For example,
safety issues such as fire and explosion, health effects such as carcinogenicity
and endocrine disruption, and environmental impacts such as global warming
and impacts on wildlife. Society's growing concern for the environment and
pressures for greater control of chemicals in the environment has now coalesced
in the arena of 'Sustainable Development'. Green chemistry is a major compo-
nent in the way that chemistry as well as the chemical and related industries,
have led and responded to sustainable development.
The term 'green chemistry' was first coined by the US Environmental Pro-
tection Agency. Their early definition of the subject is still widely quoted:
'''Green Chemistry'' is the utilization of a set of principles that reduces or elim-
inates the use or generation of hazardous substances in the design, manufacture
and application of chemical products'. However, in practice green chemistry is
nowadays taken to cover a much broader range of issues than the definition
suggests. Using and producing better chemicals with less waste, green chemistry
also involves reducing other associated environmental impacts, in particular
reducing the amount of energy used in chemical processes.
In practice, green chemistry embraces concepts such as (a) atom efficiency -
designing processes to maximize the amount of raw material that is converted
into the product; (b) energy conservation - designing more energy efficient
processes; (c) waste minimization - recognizing that the best form of waste
disposal is not to create waste in the first place; (d) substitution - using safer,
more environmentally benign raw materials and solvents or solvent free
processes.
Although the importance of green chemistry and its environmental impact
has been widely acknowledged, little work has been pursued to apply these
principles in the growing area of nanotechnology. Nanotechnology is a new
field of science broadly defined as research and technology development
intended to create, understand and use nano scale (0.1-100 nm) structures or
devices. Nanotechnology applies the principles of engineering, electronics,
physical and materials science and manufacturing to molecular and submicron
