PET and aluminum recycling from multilayer food packaging using supercritical ethanol

Different properties, such as barriers to gas, light, flavor and water vapor, as well as flexibility, are necessary for the production of food packages. These properties may be obtained by combining different polymers. In spite of the advantages achieved with the use of multilayer films, the recycling process of such material is a challenging task. This study presents an alternative for recycling of a quite common food packaging kind, which contains polyethylene (PE), aluminum and poly(ethylene terephthalate) (PET) as a multilayer film. The multilayer packages were delaminated with acetone. PET was depolymerized by ethanol in supercritical conditions. The diethyl terephthalate (DET) was obtained as the main product, presenting high purity and yield of 80%. Also, metallic aluminum was obtained by the PET-depolymerizing process. The optimal reaction time was 120 min. The products were characterized by FTIR, 1H NMR and 13C NMR spectroscopies, DSC and TGA.

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► A quite common kind of food packaging, containing PE, aluminum and PET, was recycled.
► In PET depolymerization by supercritical ethanol, diethyl terephthalate was obtained.
► High purity diethyl terephthalate was obtained, as confirmed by DSC and NMR.
► Metallic aluminum was obtained after PET depolymerization.
► PE could be easily recycled by other processes.