Alkali-decomposition of poly(ethylene terephthalate) in mixed media of nonaqueous alcohol and ether. Study on recycling of poly(ethylene terephthalate)

Alkali-decomposition (depolymerization) of poly(ethylene terephthalate) (PET) was studied in a mixed solvent of an alcohol (ethanol or methanol) and ether (dioxane, tetrahydrofuran, or dimethoxyethane). The time for complete decomposition (>96%) of solid PET with NaOH in methanol al 60 degrees C was 40 min when dioxane (10 vol%) was added as co-solvent in the reaction mixture, whereas 7h without dioxane. Disodium terephthalate, a product, precipitated quantitatively in the media and was separated easily. From the filtrate, ethylene glycol (EG) was recovered by distillation while, for practical use. the major portion of the filtrate was recycled repeatedly as the reaction medium.