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PROJECT BACKGROUND
The “How Can We Prevent
Chemical Pollution and Waste?” project challenges students in high
school chemistry classes to critically evaluate the environmental and
human health impact of a lab activity from a general chemistry lab at a
local school or college. “Green
chemistry,” a term coined by the Environmental Protection Agency in the
1990s to describe the practice of chemistry that seeks to reduce the
chemical profession’s impact on the environment, provides the framework
students work within when evaluating the lab activities at other
schools. The students use the set of 12
green chemistry principles listed in Table 1 to evaluate and redesign
the lab activity. More information about
the EPA’s Green Chemistry program is available at http://www.epa.gov/greenchemistry/:
Table 1.
The Twelve Principles of Green Chemistry
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1.
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Prevention
It is
better to prevent waste than to treat or clean up waste after it has
been created.
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2.
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Atom
Economy
Synthetic
methods should be designed to maximize the incorporation of all
materials used in the process into the final product.
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3.
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Less
Hazardous Chemical Syntheses
Wherever
practicable, synthetic methods should be designed to use and generate
substances that possess little or no toxicity to human health and the
environment.
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4.
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Designing
Safer Chemicals
Chemical
products should be designed to effect their desired function while
minimizing their toxicity.
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5.
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Safer
Solvents and Auxiliaries
The
use of auxiliary substances (e.g., solvents, separation agents, etc.)
should be made unnecessary wherever possible and innocuous when used.
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6.
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Design
for Energy Efficiency
Energy
requirements of chemical processes should be recognized for their
environmental and economic impacts and should be minimized. If
possible, synthetic methods should be conducted at ambient temperature
and pressure.
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7.
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Use
of Renewable Feedstocks
A raw
material or feedstock should be renewable rather than depleting
whenever technically and economically practicable.
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8.
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Reduce
Derivatives
Unnecessary
derivatization (use of blocking groups, protection/ deprotection,
temporary modification of physical/chemical processes) should be
minimized or avoided if possible, because such steps require additional
reagents and can generate waste.
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9.
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Catalysis
Catalytic
reagents (as selective as possible) are superior to stoichiometric
reagents.
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10.
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Design
for Degradation
Chemical
products should be designed so that at the end of their function they
break down into innocuous degradation products and do not persist in
the environment.
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11.
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Real-time
analysis for Pollution Prevention
Analytical
methodologies need to be further developed to allow for real-time,
in-process monitoring and control prior to the formation of hazardous
substances.
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12.
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Inherently
Safer Chemistry for Accident Prevention
Substances
and the form of a substance used in a chemical process should be chosen
to minimize the potential for chemical accidents, including releases,
explosions, and fires.
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*Anastas, P. T.; Warner,
J. C. Green Chemistry: Theory and Practice, Oxford University
Press: New York,
1998, p.30. http://www.chemistry.org/portal/a/c/s/1/acsdisplay.html?DOC=greenchemistryinstitute\whatare\12-principles-green-chemistry.html
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An effort to involve schools in the
quest for “greener” chemistry is exemplified by the State of Illinois
Environmental Protection Agency’s “Greening Schools” program (http://www.greeningschools.org/). To prepare students for the analysis
from the green chemistry perspective, students will be involved in
several lab activities that connect ecology with chemistry over the
course of four and a half weeks. The ecological activities consist of a
lab and internet research aimed at helping them discover how pollution
affects plant life in Barton Creek, a popular creek in Austin. Another lab has students create their own
habitat to discover and report through a presentation the effects of
pollution on both plant and animal life.
After
students develop an understanding of the impacts of pollution, the
chemistry lessons develop the students’ skills needed to assess lab
activities’ impact on the environment. The
chemistry benchmark lessons cover the dimensional analysis and
stoichiometry skills needed to assess the second green chemistry
principle of economizing atoms. The
laboratory lesson that has students create ethanol from molasses
exposes students to the seventh green chemistry principle of using
chemicals from renewable feedstocks. Additional
laboratory exercises that demonstrate green chemistry principles are
available at the University
of Oregon’s Green
Chemistry website: http://www.uoregon.edu/~hutchlab/greenchem/
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