Chemical recycling: comparative study about the depolymerization of PET waste-bottles to obtain terephthalic acid.

Currently, the plastic packaging industry in Brazil is the second largest producer in the packaging sector, with approximately 35% of the total packaging produced per year. Out of this total, 572 thousand tons are composed of polyethylene terephthalate plastic bottles (PET).

In the ranking of the main materials discarded in the country, plastic occupies the third position and, in most cases, inadequately. The recycling industries are growing constantly seeking to reuse the materials and reduce the impacts caused by this inadequately discard, even so, it’s not enough to switch back. Not even a newly discovered bacterium (Ideonella sakaiensis 201-F6), which is capable of metabolizes that polymer, can be seen as an immediately solution, because the processes are not already optimized or sized for such a large volume of PET.

Objectifying minimizes the amount of PET packaging improperly discarded and to instigate the industrial interest in the subject, our work pursued a viable path, as clean as possible in the principles of Green Chemistry, to depolymerize it. Obtaining the terephthalic acid as the main product, which is commercially obtained by oil sources and using salts and oxide of zinc as catalyzers in water as solvent, besides using inorganic bases as catalyzers in alcohols as solvent, including glycerol, which is a sub product of Biodiesel Industries. The reactions were made by refluxing (traditional way) and by microwave, where was used the reactor Biotage Initiator Plus. The products were characterized by Fourier Transformed Infrared Spectroscopy (FTIR of Bruker) and Ultra Performance Liquid Chromatography with Mass Spectrometer with Electrospray Ionization (UPLC-ESI/MS), where the results were better while using zinc sulfate as catalyzer in water and potassium hydroxide as catalyzer in pentan-1-ol.