Recycling Solvents in the Chemistry Lab

Teaching labs in the chemistry department have large numbers of inexperienced students dealing with chemicals of all sorts. These chemicals range from the reagents being used for a synthesis to solvents being used for the cleanup of glassware. When a procedure is written, the minimal amount of starting materials and solvents needed for reactions or work-up is usually suggested. In my experience, undergraduates usually do a fair job of sticking to the suggested amounts, which minimizes cost and waste for the department. In the case of glassware cleaning and drying, acetone is used universally in this Chemistry department, and many others around the globe. Glassware cleaning is an area where no volume amount is suggested to students and, as a result, copious amounts of acetone is used and wasted in the labs daily.

I teach, coordinate, and run the Advanced Inorganic Synthesis lab here at The University of Arizona. Chemicals, particularly solvents, are a major portion of the chemical cost associated with the lab course and makes up a bulk of the lab fees paid by each student. Acetone is used to clean and dry glassware and nuclear magnetic resonance (NMR) tubes, but is also used as a solvent in some of the experiments performed in my class. It is not uncommon to go through 10-15 gallons of acetone in a semester with a 32-person class. This can cost up to $300-$500 depending on the grade and vendor, and obviously is a huge amount of waste each semester. Much of this is due to washing glassware with unnecessary amounts of the solvent. Purification systems exist and are used in the department for the larger chemistry courses, such as organic chemistry. If it were not for the costs of these purification systems, they would currently be implemented into my lab. Until then, what is the solution to students wasting so much acetone? My current solution is not leaving it out by the sinks or waste hood (where it is normally kept for easy accessibility to the student). I have found students do not go out of their way to look for it unless they feel it is truly necessary for cleaning.

Another way I have started to search for a solution to this issue is through a special project. The special project I have implemented into my curriculum is intended to force the students to start thinking about what they are doing and the impacts associated with simply following the procedure. For their project, the students take a lab previously performed and make it “greener” by implementing one or more of the 12 Principles of Green Chemistry to the existing procedure. Last semester a student decided to use the recycled acetone from the organic chemistry labs in place of new acetone for a results comparison. The experiment run was the oxidation of alcohols using a Ruthenium catalyst. The efficiency of the oxidation was determined using turn over frequencies (TOF), and NMR was used to characterize the products. The TOF values in each case were similar and NMR results showed the desired peaks were present in both samples with similar intensities, indicating the recycled acetone was just as successful as using new acetone in this particular experiment.

Due to the results of this special project I am currently working on writing a grant for a similar purification system used by the organic division. The hope is that other experiments show similar results and solvents can be recycled not only for cleaning glassware but also for use in reactions. This would not only cut back costs for the mandatory student lab fee but will also allow far less waste. In acetone’s case, we could eliminate 10-15 gallons of waste each semester from my class! The next step is to see how many reactions currently implemented in the curriculum can support the use of recycled solvents.

Faculty Advisor