Circular Economy Electrochemistry: Creating Additive Manufacturing Feedstocks for Caffeine Detection from Post- Industrial Coffee Pod Waste

Author(s)

Sigley, Evelyn ; Kalinke, Cristiane ; Crapnell, Robert D. ; Whittingham, Matthew J. ; Williams, Rhys J. ; Keefe, Edmund M. ; Janegitz, Bruno Campos ; Bonacin, Juliano Alves ; Banks, Craig E.

• Document type: Journal article
• Source: ACS SUSTAINABLE CHEMISTRY & ENGINEERING; v. 11, n. 7, p. 11-pg., 2023-02-20.

Abstract

The recycling of post-industrial waste poly(lactic acid) (PI-PLA) from coffee machine pods into electroanalytical sensors for the detection of caffeine in real tea and coffee samples is reported herein. The PI-PLA is transformed into both nonconductive and conductive filaments to produce full electroanalytical cells, including additively manufactured electrodes (AMEs). The electroanalytical cell was designed utilizing separate prints for the cell body and electrodes to increase the recyclability of the system. The cell body made from nonconductive filament was able to be recycled three times before the feedstock-induced print failure. Three bespoke formulations of conductive filament were produced, with the PI-PLA (61.62 wt %), carbon black (CB, 29.60 wt %), and poly(ethylene succinate) (PES, 8.78 wt %) chosen as the most suitable for use due to its equivalent electrochemical performance, lower material cost, and improved thermal stability compared to the filaments with higher PES loading and ability to be printable. It was shown that this system could detect caffeine with a sensitivity of 0.055 +/- 0.001 mu A mu M-1, a limit of detection of 0.23 mu M, a limit of quantification of 0.76 mu M, and a relative standard deviation of 3.14% after activation. Interestingly, the nonactivated 8.78% PES electrodes produced significantly better results in this regard than the activated commercial filament toward the detection of caffeine. The activated 8.78% PES electrode was shown to be able to detect the caffeine content in real and spiked Earl Grey tea and Arabica coffee samples with excellent recoveries (96.7-102%). This work reports a paradigm shift in the way AM, electrochemical research, and sustainability can synergize and feed into part of a circular economy, akin to a circular economy electrochemistry. (AU)

• FAPESP's process: 19/01844-4 - Development of nanostructured electrodes for determination of agrotoxic residues in honey
• Grantee: Paulo Roberto de Oliveira
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 19/00473-2 - Development of 3-dimensional (3D) printed electrochemical biosensors with PLA polymer and graphene for the determination of biomolecules and diagnosis of diseases
• Grantee: Cristiane Kalinke
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 17/21097-3 - Bee-agriculture interactions: perspectives to sustainable use
• Grantee: Osmar Malaspina
• Support Opportunities: BIOTA-FAPESP Program - Thematic Grants
• FAPESP's process: 21/07989-4 - Additive-manufactured (3D printed) electrochemical devices for the diagnosis of viral diseases
• Grantee: Cristiane Kalinke
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• FAPESP's process: 13/22127-2 - Development of novel materials strategic for integrated analytical devices
• Grantee: Lauro Tatsuo Kubota
• Support Opportunities: Research Projects - Thematic Grants