Poly(ethylene terephthalate) (PET) is one of the most versatile engineering plastics, used to
manufacture mainly textiles and bottles for packaging. PET is produced by polycondensation
reaction of a di-acid and a di-alcohol [0]. The industrial synthesis is based on the reaction between
dimethyl terephthalate (DMT) and ethylene glycol (EG), forming bis-(0-hydroxyethyl)
terephthalate (BHET) as the first step. In the second step, the BHET is heated under vacuum and in
the presence of a specific catalyst to yield PET [0]. PET is largely used in the beverage industry and
food packaging industry, because it does not have any side effects on human beings. PET does not
create a direct hazard to the environment but, due to its substantial fraction by volume in the waste
stream and its high resistance to the atmospheric and biological agents, it is seen as a environmental
noxious material [0]. So, PET recycling represents one of the most successful and widespread
examples of polymer recycling. One of the PET recycling kind is the chemical modification of postconsumer PET, and sulfonation is one of the possible chemical recycling for PET [0]. Articles about
the use of sulfuric acid as acid hydrolysis agent of post-consumer PET have been published [0, 0-0].
The depolymerization reaction of PET with water in an acid medium (H0
SO0
) can carried out
according to the following scheme shown in Figure 0: