Processing Poly (ethylene terephthalate) Waste into Functional Carbon Materials by Mechanochemical Extrusion

Abstract

With the plastic pollution becoming worse, the upcycling of plastic waste into functional materials is a great challenge. Herein, a mechanochemical extrusion approach was developed for processing poly(ethylene terephthalate) (PET) waste into porous carbon materials. The essence of the cyclic extrusion approach lies in the solvent‐free mixing of thermoplastic PET with pore‐directing additive (e. g., silica or zinc chloride) at the molecular level. PET waste could be upcycled into functional carbon with high surface area (up to 1001 m2 g−1), specific shapes, and preferred mechanical strength, after cyclic extrusion and carbonization. Moreover, metal species could be well dispersed onto porous carbons through solvent‐free extrusion, different from traditional loading methods (impregnation method, deposition‐precipitation method). In this manner, mechanochemical extrusion provides an alternative for upcycling plastic waste into value‐added materials.

Mechanochemistry Milling of Waste Poly(Ethylene Terephthalate) into Metal–Organic Frameworks

“…To further confirm the component and calculate the yield of H 2 BDC, the mixture after milling is dissolved in water and filtered to obtain Na 2 BDC aqueous solution, which is acidified by 1 m HCl to form H 2 BDC precipitation. 1 H and 13 C NMR spectra confirm the existence of Na 2 BDC and ethylene glycol in the Na 2 BDC aqueous solution, as well as the formation of H 2 BDC with high purity after acidification (Figures S9 and S10). Supportively, FTIR spectra of PET and the derived H 2 BDC powder verify the conversion of PET into monomer (Figure S11).…”

“…[60] Moreover, the stretching vibration of metal-oxygen bond is confirmed by the peak located at around 550 cm À 1 . [61] To verify the chemical structure of MOFs, solid-state 13 C nuclear magnetic resonance ( 13 C NMR) spectroscopy was con- ChemSusChem ducted (Figure 5). For PET, the chemical shifts at 163, 134, 130, and 61 ppm are ascribed to the ester carboxyl carbon (1), non-protonated aromatic carbon (2), protonated aromatic carbon (3), and glycol methylene carbon (4), respectively.…”

“…FTIR spectroscopy was applied to reveal the functional groups of MOFs by INVENIOÀ R spectrometer. Solid-state 13 C NMR spectroscopy was conducted by Bruker 400 M spectrometer, while 1 H and 13 C NMR spectroscopy were performed by AscendTM 600 MHz spectrometer. XPS was carried out on VG ESCALAB MK II spectrometer to study the surface element composition and chemical valence of MOFs.…”

“…Mechanical recycling usually leads to low‐quality products [8] . In contrast, chemical upcycling, which can convert plastic wastes into high‐quality monomers/oligomers or high‐value chemical products, has drawn great attention for the sustainability and profitability [9–14] . For example, chemical upcycling of PET is being extensively investigated to produce valuable chemicals, materials, and fuels by hydrolysis, solvolysis, hydrogenolysis, pyrolysis, and others [15–18] .…”

“…[8] In contrast, chemical upcycling, which can convert plastic wastes into high-quality monomers/oligomers or high-value chemical products, has drawn great attention for the sustainability and profitability. [9][10][11][12][13][14] For example, chemical upcycling of PET is being extensively investigated to produce valuable chemicals, materials, and fuels by hydrolysis, solvolysis, hydrogenolysis, pyrolysis, and others. [15][16][17][18] Kratish et al employed a carbon-supported single-site molybdenum-dioxo catalyst to selectively depolymerize PET into H 2 BDC and ethylene under 1 bar H 2 atmosphere at 260 °C.…”