Solubilization and Upgrading of High Polyethylene Terephthalate Loadings in a Low-Costing Bifunctional Ionic Liquid
[1];
[5];
- Deconstruction Division, Joint BioEnergy Institute, 5885 Hollis Street Emeryville 94608 CA USA; Biological and Engineering Sciences Center, Sandia National Laboratories, 7011 East Avenue, Livermore 94551 CA USA
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland 99352 WA USA
- Advanced Light Source Scientific Support Group, Lawrence Berkeley National Laboratory, 1 Cyclotron Road Berkeley 94720 CA USA
- Deconstruction Division, Joint BioEnergy Institute, 5885 Hollis Street Emeryville 94608 CA USA; Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road Berkeley 94720 CA USA
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland 99352 WA USA; Biological Sciences Division, Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland 99352 WA USA
Polyethylene terephthalate (PET) is of significant commercial importance, but is difficult to recycle. Chemical inertness and resistance to biodegradation make the recycling of PET challenging and most solvents for PET are highly toxic. In this work, we demonstrate for the first time that a low cost (~$1.2/kg) and biocompatible ionic liquid (IL), cholinium phosphate ([Ch]3[PO4]) can play bifunctional roles in PET solubilization and glycolytic degradation. High loading of PET (10 wt%) is readily dissolved in [Ch]3[PO4] at relatively low temperatures (120 °C, 1h) and even in water-rich conditions. Tandem in situ confocal microscopy and Fourier Transform Infrared (FTIR) spectroscopy studies give detailed information on the solubilization mechanism in terms of morphological and chemical changes that occur. In depth analysis of PET-IL solution reveals that the high PET solubilization in [Ch]3[PO4] can be ascribed to significant PET depolymerization. Acid precipitation yields terephthalic acid as the dominant depolymerized monomer with a theoretical yield of ~95%. Further exploration shows that in the presence of ethylene glycol, [Ch]3[PO4] catalyzed glycolysis of PET can efficiently occur with ~100% PET conversion and ~60.6% bis(2-hydroxyethyl)terephthalate (BHET) yield under metal free conditions. The IL can be reused at least three times without an apparent decrease in activity. NMR analysis reveals that strong hydrogen bond interactions between EG and the IL play an important role for EG activation and promotion of the glycolysis reaction. This study opens up avenues for exploring environmentally benign and efficient technology of ILs for solubilizing and recycling postconsumer polyester plastics.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1439020
- Report Number(s):
- PNNL-SA-128561; 48827; KP1704020
- Journal Information:
- ChemSusChem, Vol. 11, Issue 4; ISSN 1864-5631
- Publisher:
- ChemPubSoc Europe
- Country of Publication:
- United States
- Language:
- English
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