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“Your Safer Source for Science” Greening the School Science Lab
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Greening the School Science Lab
For more than 40 years, Flinn Scientific has embraced a consistent philosophy regarding the use of chemicals in academic science labs: “Chemicals in any form can be safely stored, handled or used if the physical, chemical, and hazardous properties are fully understood and the necessary precautions, including the use of proper safeguards and personal protective equipment, are observed.”
We still believe this philosophy is appro- priate. Nevertheless, the list of banned or restricted lab chemicals continues to grow. A majority of states, for example, have banned mercury, even in thermometers. With so much negative attention on “problem” chemi- cals, the idea of “green chemistry” may seem like an oxymoron. Green chemistry, however, is real, and it carries a positive message about chemistry and science. The Green Chemistry Program was initiated by the U.S. Environmental Protection Agency in the 1990s with the goal of applying chemical principles to prevent pollution. The program calls for the design of chemical products and processes that will reduce the use and generation of hazardous substances. How can your institution benefit from the principles of green chemistry?
As your “Safer Source for Science,” Flinn Scientific believes that knowledge is the most important tool we can provide to reduce waste and improve safety. We strive to provide the most reliable and helpful information possible concerning the safe purchase, storage, handling, use, and disposal of laboratory chemicals.
Basic Principles
of Green Chemistry
Green chemistry presents a wonderful oppor- tunity for science instructors to increase safety, improve science education, and impart the values and benefits of science to the next gener- ation. The basic principles of green chemistry as they relate to academic science labs include:
• Design lab activities to avoid generating hazardous byproducts that require waste disposal.
• Substitute less hazardous and less toxic chemicals in chemical reactions or lab tests.
• Perform lab activities on a small-scale or microscale level to reduce the amounts of chemicals used.
• Use catalysts to avoid byproduct formation in chemical reactions.
• Use safer solvents.
• Avoid high temperature or high pressure conditions for chemical reactions.
Reviewing and Planning
Lab Activities
To implement green chemistry, faculty and staff need to know what chemicals are being used in lab activities. This requires two things—an accurate inventory of chemicals, and a list of chemicals used in experiments and demonstrations for all lab courses. The second requirement may seem like tall order, but it is vital. After compiling this list of chemicals, most departments find that half of the chemicals in their inventory are never used! In reviewing current lab activities, carefully compare the hazards of chemicals versus the learning goals and objectives. A lab activity may use lead nitrate, for example, to precipitate lead iodide and demonstrate crystal formation. No doubt, it is a beauti- ful demonstration! Is the need for licensed hazardous waste disposal of the heavy metals used in this demonstration justified in terms of the learning goals? Would another demon- stration accomplish the same objective? Mixing copper chloride and sodium phos- phate solutions gives a turquoise solid. This reaction is “greener” and safer than lead iodide.
Set up regular department meetings to discuss some of the “not so green” lab activi- ties in the curriculum and to share ideas for possible alternatives. Also, don’t think that just because you don’t have time to review every single chemical, you shouldn’t do anything. Remember, a journey of a thousand miles begins with a single step. Take the first step!
Advantages of Microscale Labs
The advantages of microscale lab activi- ties are well known—the labs are faster, so students can do more trials and gather more data, students and instructors are exposed to lower concentrations of possibly hazardous chemicals (especially for vola- tile substances), departments save money
in the cost of chemicals, glassware, and equipment, faculty and staff spend less time setting up and cleaning up, and the amount of waste generated is greatly reduced. Many common lab activities can be reduced to the microscale level simply by combining drops of liquids in a well plate instead of mixing milliliters of liquid in a beaker.
Color the Curriculum Green!
Try the following suggestions to get started on the path to greener science labs in your school:
• Incorporate disposal treatment into the lab
procedure—neutralize acid products with sodium carbonate, reduce halogen waste with sodium thiosulfate, precipitate silver ions with sodium chloride, etc.
• Purchase digital thermometers—they are safer and more precise than spirit-filled glass thermometers.
• Use lower concentrations or less hazardous forms of chemicals whenever possible.
−Always work with the lowest concen- tration possible of strong acids. If a procedure calls for 3 M hydrochloric acid, try 1 or 2 M HCl. Copper wire requires concentrated nitric acid to dissolve, but copper foil will dissolve in 6 M HNO .
3 −Substitute solutions for pure solids when- ever possible. The LD50 of copper(II) chloride is 140 mg/kg—extremely toxic. Using 1 M CuCl2 solution reduces the toxicity hazard almost tenfold! There is also a reduced risk of exposure to toxic fumes or dust when working with
The goals of the Green Chemistry Program are embodied in the Twelve Principles of Green Chemistry, origi- nally published by Paul Anastas and John Warner in 1998, which provide a roadmap for scientists to reduce and prevent pollution. The program supports fundamental research, spon- sors educational and scientific outreach activities, and recognizes achieve- ment through the Presidential Green Chemistry Challenge Awards. For more information about the principles of green chemistry, visit the EPA Web site at www2.epa.gov/greenchemistry/ basics-green-chemistry.
solutions.
−Avoid finely divided forms of metals.
Granular zinc is safer than zinc dust; magnesium ribbon is safer than magne- sium powder. Finally divided metals may be both a reactivity or flammability hazard (Zn, Mg) and an inhalation hazard (Pb, Cr, etc).
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