Abstract
Biodegradable polymers undergo a degradation process resulting from the action of microorganisms such as bacteria, fungi and algae. Poly(butylene adipate co-terephthalate) (PBAT) is considered a biodegradable synthetic polymer, even if its degradation has been confirmed under industrial composting conditions, the investigation of its degradation in the marine environment is still limited. Therefore, this work aims to study the biodegradation in the marine environment, of the biodegradable polymer (PBAT), and for that, it was submerged in a static system, using seawater from the coastal region of Pernambuco/Brazil as a fluid. The samples were studied by chemical, thermal and microbiological analyses, after 7, 14, 30, 90, 120 and 180 days of immersion. Microbiological analyzes indicated that aerobic heterotrophic bacteria (AHB), anaerobic heterotrophic bacteria (AnHB) and iron precipitating bacteria (IPB) were quantified in the system at all times at high concentrations, with the exception of Sulfate reducing bacteria (SRB), fungi and Pseudomonas that showed lower concentrations compared to other bacterial groups. Biodegradation was observed by the percentage of mass loss of approximately 2.25%. In the DSC, the expansion of melting peaks after exposure to the marine environment was noted, while the TGA did not show changes in the curve trends. The FTIR showed that no new band appeared, nor displacement, since the vibrations of the covalent bonds of the groups are present regardless of the biodegradation. Indicating that no significant microbiological degradation of PBAT was observed.
Highlights
The growing concern with the disposal of synthetic polymers, observed in recent decades, due to their enormous quantity and environmental impact, has motivated the search for the development of biodegradable polymers (Andrade et al., 2021)
The results showed that after 124 days 95% of the Poly(butylene adipate co-terephthalate) (PBAT) content had been mineralized to carbon dioxide and that during the initial periods the PBAT strips were in contact with soil microorganisms were covered with microbial biofilms
Other studies were found for the concentration of microorganisms in seawater at the port of Recife-PE: Argolo et al, (2015) quantified the same microbial groups and obtained values of around 106 cells/ml for aerobic heterotrophic bacteria (AHB) and iron precipitating bacteria (IPB), 105 cells/ml for anaerobic heterotrophic bacteria (AnHB) and 103 cells/ml for SHB
Summary
The growing concern with the disposal of synthetic polymers, observed in recent decades, due to their enormous quantity and environmental impact, has motivated the search for the development of biodegradable polymers (Andrade et al., 2021). PBAT is an aliphatic-aromatic, thermoplastic, synthetic copolyester and has an accelerated degradation process, which can degrade in a few weeks in contact with a favorable environment, through the action of natural enzymes, because its chemical structure is composed of an aliphatic fraction (adipate butadiene), responsible for its biodegradability, and an aromatic part (terephthalate), which provides good mechanical properties, having a maximum elongation of 700%, as well as maintaining integrity of the polymer, making its degradation difficult (Shahlari & Lee, 2012). Degradability, is due to the presence of enzymes that cause PBAT to completely degrade in a few weeks. This process has been studied for some years, and investigations are focused on degradation under variable environmental conditions. The results showed that after 124 days 95% of the PBAT content had been mineralized to carbon dioxide and that during the initial periods the PBAT strips were in contact with soil microorganisms were covered with microbial biofilms
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