It is better to prevent waste than to treat or clean up waste after it is formed.
Pollution prevention can be practiced in the lab by implementing just about any of the principles of Green Chemistry. For example, by investigating alternative solvents or by using no solvent at all (principle #5), solvent waste is reduced or eliminated. By switching to a catalytic reagent rather than a stoichiometric reagent (principle #9), much waste can be also be avoided. As you learn about each of the principles of Green Chemistry, you will learn that many of them are inter-related. Principle #1, Pollution Prevention, is the most over-arching of all the principles and when many of the other principles are practiced correctly, this principle is also acheived.
Within the laboratory setting, there are simple laboratory practices that will reduce your lab's environmental impact. Many of these are tied to conservation practices, rather than Green Chemistry, however, these simple improvements of common practices have a large effect.
- Use recirculating water baths:
- Traditional "once-through cooling" systems consist of water coming in through a spigot, circulating through some glassware (a condenser, for example) and leaving through a drain at a fairly high flow rate. This wastes a great deal of water. Recirculating water baths reuse a known amount of water and can be used for many cooling purposes within the laboratory setting. Not only does this prevent waste, it prevents flooding should any tubing come loose. Inexpensive recirculating water baths can be made by using a fish tank pump and styrofoam cooler (with ice water) for less than $20 for each set-up!
- Use water aspirators instead of sink water for vacuum purposes:
- If you do not have house vacuum within your laboratory setting, then consider purchasing a water aspirator that can be used to provide a vacuum for your filtering needs. This considerably reduces the amount of water used for regular water and sink aspirators.
- Conduct experiments on a small scale:
- Especially when conduction an experiment for the first time, minimize the amount of starting matterials and solvents you invest.
- Determine ideal conditions before scale-up:
- You can prevent waste and wasteful reactions by simply making sure you have the ideal conditions (limiting reagents, starting material ratios, solvent volumes, temperature, approximate heating times, etc.) needed for your synthesis. This can also include double-checking your calculations! Before weiging out your reactants, check your math to be sure you know the amounts you need. In a teaching lab make sure both lab partners do the calculations and check the numbers with an instructor or teaching assistant before beginning.
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