Ohmic Heating as a Strategy for Upcycling PET Plastic Waste for New Supramolecular Structures
6 affiliations
- 1LAQV-REQUIMTE, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, 4169-007 Porto, Portugal
- 2LAQV-REQUIMTE, Chemistry Department, NOVA School of Science and Technology, NOVA FCT, Campus de Caparica, 2829-516 Caparica, Portugal
- 3CIMAR, Instituto de Ciências Biomédicas de Abel Salazar, University of Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal
- 4CIQUP, Institute of Molecular Sciences (IMS), Departamento de Química e Bioquímica, Faculdade de Ciências, University of Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal
- 5LNEG—National Laboratory of Energy and Geology IP, Campus do Lumiar, 1649-038 Lisboa, Portugal
- 6LAQV-REQUIMTE, School of Medicine and Biomedical Sciences, University of Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal
Abstract
The massive accumulation of poly(ethylene terephthalate) (PET) plastic waste poses a significant global environmental challenge, requiring the development of more sustainable upcycling strategies. This study investigated the alkaline hydrolysis of PET flakes to recover terephthalic acid (TPA) using ohmic heating and compared its performance with conventional and microwave heating methods. The sequential PET loading in the same reaction medium, as well as the use of opaque white and opaque colored PET feedstocks, was also evaluated. The spectroscopic characterization by 1H NMR and powder X-ray diffraction (PXRD) confirmed the successful recovery of TPA from different PET sources. This recovered TPA was subsequently co-crystallized with 4-(dimethylamino)pyridine (DMAP) and 4-aminopyridine (AP) in low-temperature methanol to synthesize new supramolecular structures 1 and 2, respectively. Both compounds were characterized by scanning electron microscopy (SEM) and PXRD. Single-crystal X-ray diffraction analysis of compound 1 revealed a three-dimensional supramolecular network stabilized by ionic/hydrogen bonding interactions between the TPA and DMAP units. Overall, ohmic heating emerged as a potentially energy-efficient and sustainable approach for PET hydrolysis. Furthermore, the successful synthesis of these supramolecular architectures demonstrates that recycled TPA can serve as a valuable building block for advanced functional materials, highlighting a promising route for the high-value upcycling of PET waste.
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BibTeX
@article{guimaraes2026ohmic,
title = {{Ohmic Heating as a Strategy for Upcycling PET Plastic Waste for New Supramolecular Structures}},
author = {Susana Guimarães and Susana L. H. Rebelo and Sandra Gago and Maria A. Salgado and Luís M. N. B. F. Santos and Salete S. Balula and Luís Cunha-Silva and Ana M. G. Silva},
journal = {Molecules},
year = {2026},
month = oct,
doi = {10.3390/molecules31203698},
url = {https://www.mdpi.com/1420-3049/31/20/3698},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Ohmic Heating as a Strategy for Upcycling PET Plastic Waste for New Supramolecular Structures
AU - Susana Guimarães
AU - Susana L. H. Rebelo
AU - Sandra Gago
AU - Maria A. Salgado
AU - Luís M. N. B. F. Santos
AU - Salete S. Balula
AU - Luís Cunha-Silva
AU - Ana M. G. Silva
PY - 2026
DA - 2026/10/01
JO - Molecules
DO - 10.3390/molecules31203698
UR - https://www.mdpi.com/1420-3049/31/20/3698
AB - The massive accumulation of poly(ethylene terephthalate) (PET) plastic waste poses a significant global environmental challenge, requiring the development of more sustainable upcycling strategies. This study investigated the alkaline hydrolysis of PET flakes to recover terephthalic acid (TPA) using ohmic heating and compared its performance with conventional and microwave heating methods. The sequential PET loading in the same reaction medium, as well as the use of opaque white and opaque colored PET feedstocks, was also evaluated. The spectroscopic characterization by 1H NMR and powder X-ray diffraction (PXRD) confirmed the successful recovery of TPA from different PET sources. This recovered TPA was subsequently co-crystallized with 4-(dimethylamino)pyridine (DMAP) and 4-aminopyridine (AP) in low-temperature methanol to synthesize new supramolecular structures 1 and 2, respectively. Both compounds were characterized by scanning electron microscopy (SEM) and PXRD. Single-crystal X-ray diffraction analysis of compound 1 revealed a three-dimensional supramolecular network stabilized by ionic/hydrogen bonding interactions between the TPA and DMAP units. Overall, ohmic heating emerged as a potentially energy-efficient and sustainable approach for PET hydrolysis. Furthermore, the successful synthesis of these supramolecular architectures demonstrates that recycled TPA can serve as a valuable building block for advanced functional materials, highlighting a promising route for the high-value upcycling of PET waste.
SN - 1420-3049
ER -