Uncatalyzed Neutral Hydrolysis of Waste PET Bottles into Pure Terephthalic Acid
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ACS Publications
Abstract
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Hydrolysis of waste polyethylene terephthalate (PET) into terephthalic acid (TPA) is a
promising recycling method to manage this waste and can also serve as a feedstock for
the re-production of PET. However, the drawbacks of this recycling method are the low
degradation efficiency, complex/ecounfriendly separation of products, and low TPA
purity. In this work, waste PET bottles were completely depolymerized using an
uncatalyzed neutral hydrolysis, which was accompanied by a very simple solid product
separation with no purification step. The influences of experimental parameters, such as
hydrolysis time, the addition of ethylene glycol cosolvent, and the PET/water ratio on the
TPA yield and purity, were investigated. Qualitative analyses showed that the solid
product from the hydrolysis process was TPA, which was consistent with commercial
purified TPA. The results showed that a long hydrolysis time, in the absence of any
catalyst and a very high PET/water ratio, favored increased TPA yield, selectivity, and
purity. The TPA yield increased from ∼86 to ∼98% as the hydrolysis time increased
from 6 to 24 h. Furthermore, the TPA consisted of large particles and was easy to
obtain without any complex extractive and purification processes. This facile and green
approach for the depolymerization of waste PET to pure TPA with no
isolation/purification steps promises a more efficient and inexpensive route for its full
commercialization.
Keywords
QD Chemistry