A Systematic Study on the Degradation Products Generated from Artificially Aged Microplastics
Most of the analytical studies focused on microplastics (MPs) are based on the detection and identification of the polymers constituting the particles. On the other hand, plastic debris in the environment undergoes chemical and physical degradation processes leading not only to mechanical but also t...
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| Format: | Article |
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MDPI AG
2021-06-01
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| Series: | Polymers |
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| Online Access: | https://www.mdpi.com/2073-4360/13/12/1997 |
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| author | Greta Biale Jacopo La Nasa Marco Mattonai Andrea Corti Virginia Vinciguerra Valter Castelvetro Francesca Modugno |
| author_facet | Greta Biale Jacopo La Nasa Marco Mattonai Andrea Corti Virginia Vinciguerra Valter Castelvetro Francesca Modugno |
| author_sort | Greta Biale |
| collection | DOAJ |
| description | Most of the analytical studies focused on microplastics (MPs) are based on the detection and identification of the polymers constituting the particles. On the other hand, plastic debris in the environment undergoes chemical and physical degradation processes leading not only to mechanical but also to molecular fragmentation quickly resulting in the formation of leachable, soluble and/or volatile degradation products that are released in the environment. We performed the analysis of reference MPs–polymer micropowders obtained by grinding a set of five polymer types down to final size in the 857–509 μm range, namely high- and low-density polyethylene, polystyrene (PS), polypropylene (PP), and polyethylene terephthalate (PET). The reference MPs were artificially aged in a solar-box to investigate their degradation processes by characterizing the aged (photo-oxidized) MPs and their low molecular weight and/or highly oxidized fraction. For this purpose, the artificially aged MPs were subjected to extraction in polar organic solvents, targeting selective recovery of the low molecular weight fractions generated during the artificial aging. Analysis of the extractable fractions and of the residues was carried out by a multi-technique approach combining evolved gas analysis–mass spectrometry (EGA–MS), pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS), and size exclusion chromatography (SEC). The results provided information on the degradation products formed during accelerated aging. Up to 18 wt% of extractable, low molecular weight fraction was recovered from the photo-aged MPs, depending on the polymer type. The photo-degradation products of polyolefins (PE and PP) included a wide range of long chain alcohols, aldehydes, ketones, carboxylic acids, and hydroxy acids, as detected in the soluble fractions of aged samples. SEC analyses also showed a marked decrease in the average molecular weight of PP polymer chains, whereas cross-linking was observed in the case of PS. The most abundant low molecular weight photo-degradation products of PS were benzoic acid and 1,4-benzenedicarboxylic acid, while PET had the highest stability towards aging, as indicated by the modest generation of low molecular weight species. |
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| id | doaj.art-1a53e641e7f948e69b313a7899af80e4 |
| institution | Directory Open Access Journal |
| issn | 2073-4360 |
| language | English |
| last_indexed | 2024-03-10T10:17:16Z |
| publishDate | 2021-06-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Polymers |
| spelling | doaj.art-1a53e641e7f948e69b313a7899af80e42023-11-22T00:40:51ZengMDPI AGPolymers2073-43602021-06-011312199710.3390/polym13121997A Systematic Study on the Degradation Products Generated from Artificially Aged MicroplasticsGreta Biale0Jacopo La Nasa1Marco Mattonai2Andrea Corti3Virginia Vinciguerra4Valter Castelvetro5Francesca Modugno6Department of Chemistry and Industrial Chemistry, University of Pisa, 56124 Pisa, ItalyDepartment of Chemistry and Industrial Chemistry, University of Pisa, 56124 Pisa, ItalyDepartment of Chemistry and Industrial Chemistry, University of Pisa, 56124 Pisa, ItalyDepartment of Chemistry and Industrial Chemistry, University of Pisa, 56124 Pisa, ItalyDepartment of Chemistry and Industrial Chemistry, University of Pisa, 56124 Pisa, ItalyDepartment of Chemistry and Industrial Chemistry, University of Pisa, 56124 Pisa, ItalyDepartment of Chemistry and Industrial Chemistry, University of Pisa, 56124 Pisa, ItalyMost of the analytical studies focused on microplastics (MPs) are based on the detection and identification of the polymers constituting the particles. On the other hand, plastic debris in the environment undergoes chemical and physical degradation processes leading not only to mechanical but also to molecular fragmentation quickly resulting in the formation of leachable, soluble and/or volatile degradation products that are released in the environment. We performed the analysis of reference MPs–polymer micropowders obtained by grinding a set of five polymer types down to final size in the 857–509 μm range, namely high- and low-density polyethylene, polystyrene (PS), polypropylene (PP), and polyethylene terephthalate (PET). The reference MPs were artificially aged in a solar-box to investigate their degradation processes by characterizing the aged (photo-oxidized) MPs and their low molecular weight and/or highly oxidized fraction. For this purpose, the artificially aged MPs were subjected to extraction in polar organic solvents, targeting selective recovery of the low molecular weight fractions generated during the artificial aging. Analysis of the extractable fractions and of the residues was carried out by a multi-technique approach combining evolved gas analysis–mass spectrometry (EGA–MS), pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS), and size exclusion chromatography (SEC). The results provided information on the degradation products formed during accelerated aging. Up to 18 wt% of extractable, low molecular weight fraction was recovered from the photo-aged MPs, depending on the polymer type. The photo-degradation products of polyolefins (PE and PP) included a wide range of long chain alcohols, aldehydes, ketones, carboxylic acids, and hydroxy acids, as detected in the soluble fractions of aged samples. SEC analyses also showed a marked decrease in the average molecular weight of PP polymer chains, whereas cross-linking was observed in the case of PS. The most abundant low molecular weight photo-degradation products of PS were benzoic acid and 1,4-benzenedicarboxylic acid, while PET had the highest stability towards aging, as indicated by the modest generation of low molecular weight species.https://www.mdpi.com/2073-4360/13/12/1997microplasticspolymer degradationartificial ageingpolyolefinspolystyrenepolyethylene terephthalate |
| spellingShingle | Greta Biale Jacopo La Nasa Marco Mattonai Andrea Corti Virginia Vinciguerra Valter Castelvetro Francesca Modugno A Systematic Study on the Degradation Products Generated from Artificially Aged Microplastics Polymers microplastics polymer degradation artificial ageing polyolefins polystyrene polyethylene terephthalate |
| title | A Systematic Study on the Degradation Products Generated from Artificially Aged Microplastics |
| title_full | A Systematic Study on the Degradation Products Generated from Artificially Aged Microplastics |
| title_fullStr | A Systematic Study on the Degradation Products Generated from Artificially Aged Microplastics |
| title_full_unstemmed | A Systematic Study on the Degradation Products Generated from Artificially Aged Microplastics |
| title_short | A Systematic Study on the Degradation Products Generated from Artificially Aged Microplastics |
| title_sort | systematic study on the degradation products generated from artificially aged microplastics |
| topic | microplastics polymer degradation artificial ageing polyolefins polystyrene polyethylene terephthalate |
| url | https://www.mdpi.com/2073-4360/13/12/1997 |
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