Hydrolysis of Post-Consumer Polylactic Acid Waste

Laboratory Procedures (PDF)

Author Contact: gurney@simmons.edu

Summary

The preparation of lactic acid from (poly)lactic acid (PLA) cups is feasible at the middle school, high school and undergraduate level and can be used as a fantastic demonstration to non-science majors. Not only does it educate the community about the use of the greener Natureworks PLA cups, but it also is a visual and concrete demonstration of recycling at the molecular level. This technique transforms a waste product (PLA) into a treasure that can be used by students. Several principles of green chemistry can be directly presented to both students and the community through this laboratory experience. Historically, alchemists toiled for centuries to uncover a means of converting lead to gold. Although the search for the coveted philosopher’s stone was lost over time, the principle of converting “common” to “precious” remains highly coveted. How could one argue with a method to convert garbage to food or trash to treasure; especially if it could be done in a simple, cost effective, and environmentally friendly manner.

The link to the laboratory procedure includes background information on polymers, a laboratory procedure with instructor’s notes that have been adopted for a sophomore organic chemistry laboratory course. The generation of lactic acid from polylactic acid post-consumer waste provides a unique opportunity to involve students in the application of the Twelve Principles of Green Chemistry both in theory and in practice in a variety of laboratory courses, including general chemistry, organic chemistry, GOB series and high school. The experiment can be performed in 20 minutes if performed in a microwave or in 90 minutes if using traditional heating methods.

Summary prepared July 2008 by Dr. Rich Gurney, Department of Chemistry, Simmons College. These materials are currently in press within the Journal of Materials Education (July 2008).

Category Descriptors

Chemistry Concepts

• Catalysis
• Esters (Reactivity)
• Fatty Acids
• Polymerization
• Solutions/Solvents

Laboratory Techniques

• Biological Assays
• IR Spectroscopy
• Mass Spectrometry
• NMR Spectroscopy
• pH
• Sterile Techniques

Green Chemistry Principles

• Design for Degradation
• Design Less Hazardous Chemical Syntheses
• Design Safer Chemicals and Products
• Increase Energy Efficiency
• Maximize Atom Economy
• Prevent Waste
• Use Catalysts
• Use Renewable Feedstocks
• Use Safer Solvents/Reaction Conditions

Chemistry Subdiscipline

• Environmental Chemistry
• Materials Science
• Organic Chemistry

Target Audience

• Colleges/Universities
• General Public
• Primary Schools
• Secondary Schools

Source

• Original Contributions - unpublished