Estudo e aplicação de uma resina polimérica como inibidor de corrosão e sensor eletroquímico

Abstract

Polymers are currently the most important material in society, being used as part of building structures and food packaging. Many authors even consider that we are living in the Age of Polymers, referring to other historical moments such as the Stone Age, the Bronze Age and the Iron Age. Thus, this doctoral thesis looked at the chemical recycling of polyethylene terephthalate (PET) to obtain an organic binder for synthesizing metal organic frameworks (MOFs). Other application of chemical recycling of PET was the corrosion inhibitor of AISI304 in saline environment. Firstly, it was observed that the terephthalic acid recovered (TPAr) obtained from the alkaline hydrolysis of PET exhibited comparable purity to TPA commercially produced in the petrochemical industry. The TPAr was successfully employed in the production of a copper-based MOF (Cu-TPAr), which demonstrated excellent electrochemical sensing capabilities for caffeine and glucose. For glucose sensing, Cu-TPAr showed good linearity in the concentration range of 1.0 to 10.0 mmol L−1, with a limit of detection (LOD) of 0.23 mmol L−1 . Additionally, the material exhibited electrocatalytic activity for glucose oxidation. In the case of caffeine sensing, CuTPAr showed a slight shift in oxidation potential (30 mV) and an increase in peak current. The Cu-TPAr electrode exhibited good linearity for caffeine concentrations ranging from 25 to 125 µmol L−1 , with a LOD of 7.61 µmol L−1 . Furthermore, the polymeric resin obtained from PET chemical recycling, which was used as a dust suppressant by Vale S.A., was investigated for corrosion inhibition of AISI304 in a saline medium. The results obtained from potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques demonstrated that the polymeric resin acted as an effective anodic inhibitor. The 2.5% (w/v) resin concentration exhibited the highest corrosion inhibition efficiency for AISI304, with values of 82.2% and 77.0% obtained from potentiodynamic polarization and EIS, respectively. These findings highlight the potential of PET chemical recycling to obtain valuable materials for various applications, contributing to a sustainable environment and promoting research on the reuse of polymer-based materials.