Byproduct Valorization:From Spent Coffee Grounds to Fatty Acid Ethyl Esters

A laboratory experiment was designed to provide students with an introduction to byproduct valorization by producing an analogue of biodiesel (fatty acid ethyl esters, FAEE) via lipid extraction and subsequent transesterification from spent coffee grounds (SCG). Valorization is the process of upgrading underutilized or discarded wastes or byproducts into chemicals, materials, and (bio)energy. Upon isolation of the intermediate and FAEE, students analyzed the respective spectroscopic characteristics using infrared and nuclear magnetic resonance spectroscopy as well as evaluated gas chromatography spectra that were provided. Associated green metrics for the reaction were determined to obtain a quantitative measure of the “greenness” of the experiment. In this laboratory experiment, students are introduced to key concepts such as whole systems thinking and the United Nations Sustainable Development Goals where they apply these frameworks to real-world problems such as consumption and waste disposal. In addition to providing a greener alternative to traditional methods for biodiesel analogue production from SCG by solvent alterations, this experiment demonstrates the value of waste that would otherwise be overlooked to generate products that can help reduce the continued use of finite fossil fuels.