Good news for coffee enthusiasts was recently published in ACS Sustainable Chemistry & Engineering journal, stating that used coffee pod plastic can be recycled into filament for 3D printers. This would significantly reduce the environmental impact of used coffee pods. The study was conducted by research groups in Brazil, at the Federal University of São Carlos (USFCar) and the State University of Campinas (UNICAMP), and in the United Kingdom, at Manchester Metropolitan University (MMU).
The researchers successfully created new conductive and non-conductive filaments using waste polylactic acid (PLA) from used coffee pods. These filaments can be used for various applications, such as creating conductive parts for machinery and sensors. Bruno Campos Janegitz, co-author of the article, and head of the Sensors, Nanomedicine and Nanostructured Materials Laboratory (LSNano) at UFSCar in Araras, São Paulo state, stated that there are numerous applications for these filaments.
Brazil is the world’s leading coffee producer and exporter, with the United States being its second-largest consumer. While most coffee consumed in Brazil is of low quality, demand for gourmet and specialty coffees is on the rise. Gourmet coffees consist of selected arabica beans (Coffea arabica) with a lower roast to preserve their natural sugars, aroma, and flavor. These coffees score 75-80 on the scale used by the Brazilian Coffee Industry Association (ABIC), while specialty coffees must have a socio-environmental certification and score at least 80 on the scale used by the Brazilian Specialty Coffee Association (BSCA).
The quality of coffee not only depends on the beans but also on how it’s prepared. Many Brazilians are shifting to the cafetière or stove-top Moka pot instead of the traditional cloth or paper filter. Portable electric espresso machines that use pods are also gaining popularity, but their usage leads to the problem of disposing of used pods.
While some suppliers promote recycling of aluminum pods, most consumers simply throw used pods in the garbage bin, mainly if they are made of plastic. São Paulo State Technological Research Institute (IPT) calculations show that a cup of pod coffee can be up to 14 times more environmentally damaging than a cup of filter coffee.
To address this issue, the researchers in Brazil and the UK created electrochemical cells and sensors with non-conductive and conductive filaments made from waste polylactic acid (PLA) from used coffee pods. The conductive filaments are made by adding carbon black to the PLA. They tested the sensors to determine the caffeine content in black tea and arabica coffee.
The process of producing the filament is simple. The researchers wash and dry the used PLA pods to obtain the non-conductive material, and for conductive material, they add carbon black before heating and extrusion. The spooled filament can be used for various purposes, such as making conductive parts for machinery and sensors.
This process is a great example of a circular economy where waste from one activity is converted into resources for another activity, rather than being considered an environmental problem. It creates added value from the polymer base obtained from used coffee pods.