We can't find the internet
Attempting to reconnect
Something went wrong!
Hang in there while we get back on track
Accelerated photoaging of microplastic - polyethylene terephthalate: physical, chemical, morphological properties and pesticide adsorption
Summary
Researchers subjected polyethylene terephthalate (PET) microplastics to accelerated photoaging under simulated sunlight, characterizing changes in surface chemistry, crystallinity, and mechanical properties over time. Photoaging increased surface oxidation, reduced molecular weight, and enhanced the release of plastic additives, suggesting aged PET microplastics present greater chemical hazard than pristine particles.
Microplastics (MP) in the environment are a constant concern, as these plastic particles can have a series of negative impacts on environments, especially aquatic environments. Due to entanglement and ingestion by marine animals, microplastics can lead to the death of aquatic animals, which interferes with aquatic life and, consequently, the life of human beings. In addition to the direct mortality of animals, microplastics can be dispersed in the environment and have great potential for transporting organic and inorganic contaminants up trophic chains, due to their adsorptive capacity. With this in mind, the main aim of this study was to investigate the effect of photoaging polyethylene terephthalate (PET) microplastics on their physical, chemical and morphological properties, using accelerated aging chambers with UV-B lamps, and to correlate this with the ability of these materials to adsorb the pesticide chlorpyrifos. Samples of PET microplastic were photo-aged in a chamber containing UV-B lamps for different exposure times (1h, 4h, 6h and 8h). The morphological, chemical and structural characteristics of the materials obtained after photodegradation were monitored and compared with natural PET using Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Energy Dispersive X-Ray Spectrometry (EDS), Fourier Transform Infrared Spectroscopy (FTIR), Zero Charge Potential (pHPCZ) and Thermogravimetry (TG). The Percentage of Crystallinity (using XRD data) and Carbonyl Index (CI) (using FTIR data) were also calculated. SEM analyses revealed an increase in roughness and the appearance of pores in the PETs aged at 6 and 8 hours, which proves that the materials showed morphological changes after the photoaging process. It was not possible to observe a statistically significant reduction in the percentage of crystallinity of the photodegraded PETs when compared to natural PET, however, the infrared analysis (FTIR) revealed bands close to the 1720 cm-1 wave number, which corresponds to the carbonyl groups (C=O), which were more intense for the photo-aged materials, indicating that the materials suffered oxidation after UV-B irradiation. From the calculation of the Carbonyl Index, it was possible to observe an increase in the CI directly linked to increased exposure to UV-B radiation. Thermogravimetry showed that natural PET and PET- 1h had similar thermograms with only one degradation stage and the other PETs aged for 4h, 6h and 8h showed a second degradation peak, but with a lower intensity, indicating that there was no significant change in the thermal stability of the materials after the photo-aging process. The pHPCZ values decreased after photodegradation, probably due to the increase in oxygencontaining groups resulting from UV-B photo-oxidation. The adsorption analyses revealed a statistically significant increase in adsorption capacity for all aged PETs when compared to natural PET, with adsorption capacities of 1.31; 1.48; 1.58; 1.51 and 1.56 mg/g for PET, PET- 1h, PET-4h, PET-6h and PET-8h, respectively. Due to the increase in interaction area (increase in roughness and cavity), hydrophobic and π-π interactions between photodegraded PET and chlorpyrifos were favoured. Based on the data obtained, it is considered that PET in the environment has its physical, chemical and morphological properties altered after exposure to UV-B radiation.
Sign in to start a discussion.
More Papers Like This
Physicochemical transformation and toxic potential of polyethylene terephthalate (PET) fragments exposed to natural daylight
Researchers exposed PET plastic fragments to natural sunlight and studied how weathering changed their chemistry and toxicity. They found that sun-aged PET released a more complex mixture of chemicals, including plasticizers and metals like antimony, and became significantly more toxic to marine microalgae and bacteria. The findings highlight that plastic degradation in the environment does not make it harmless but can actually increase the danger posed by leached substances.
Photo-induced degradation of single-use polyethylene terephthalate microplastics under laboratory and outdoor environmental conditions
Researchers tested how sunlight, water, and physical wear work together to break down PET microplastics, the type commonly found in plastic bottles and food packaging. Over 60 days, combined UV light and water exposure caused significant chemical degradation of the plastic surfaces. This matters because as microplastics break down in the environment, they release smaller fragments and potentially harmful chemicals that are easier for organisms to absorb.
Aging assessment of microplastics (LDPE, PET and uPVC) under urban environment stressors
Researchers aged LDPE, PET, and uPVC microplastics using ozone, UV-C, and solar radiation to simulate urban environmental stressors, finding that each aging agent produced distinct changes in surface morphology, chemical structure, and crystallinity that could alter particle behavior in the environment.
Aging behavior of microplastics accelerated by mechanical fragmentation: alteration of intrinsic and extrinsic properties
Researchers mechanically fragmented polystyrene, polypropylene, and PET microplastics to simulate environmental aging, finding that fragmentation alters surface chemistry, crystallinity, and heavy metal adsorption capacity, with aging degree measurable through structural changes.
A comprehensive review of microplastic aging: Laboratory simulations, physicochemical properties, adsorption mechanisms, and environmental impacts
This review examines how microplastics change as they age in the environment through exposure to sunlight, water, and chemicals, becoming rougher and more chemically reactive over time. Aged microplastics absorb more pollutants than fresh ones and release harmful additives and free radicals, meaning the microplastics people encounter in the real world may be more dangerous than the pristine particles typically used in lab studies.