Piccinini Astra, Lucia Giulia, Colarossi Daniele, Principi Paolo, Amenitsch Heinz, Pittura Lucia, Regoli Francesco, Gorbi Stefania, Spinozzi Francesco
Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona, Italy.
Department of Industrial Engineering and Mathematical Sciences, Polytechnic University of Marche, Ancona, Italy.
PLoS One. 2025 Sep 10;20(9):e0328502. doi: 10.1371/journal.pone.0328502. eCollection 2025.
Microfibers are pollutants of increasing concern, as they accumulate in aquatic environments and pose risks to living organisms. Once released, they undergo degradation processes that reduce their size and enhance their ability to interact with biological systems. Among these processes, photodegradation is a key driver, leading to fiber fragmentation and structural shrinkage. This study investigates the nanostructural evolution of five common microfibers (cotton, cellulose acetate, polyamide, polyester, and linen) dispersed in seawater and freshwater, following simulated solar ultraviolet exposure equivalent to one year of environmental conditions. Using synchrotron-based Small- and Wide-Angle X-ray Scattering, we characterized changes in the internal organization of the fibers. Small-Angle X-ray Scattering data were analyzed using a multiscale model that describes macrofibrils as bundles of polydisperse core-shell microfibrils arranged in a distorted hexagonal lattice. Results reveal distinct nanostructural modifications. In seawater, cotton and polyamide show increases in microfibril spacing, resulting in macrofibril enlargement, while in freshwater their structure remains more stable or evolves irregularly. Polyester and linen exhibit a progressive reduction in macrofibril diameter in both media, suggesting a greater tendency toward fragmentation. Cellulose acetate remains structurally stable in seawater but undergoes shrinkage and partial reorganization in freshwater. Wide-Angle X-ray Scattering confirms the presence of crystalline phases in cotton, linen, and polyamide, and reveals medium-specific variations in crystallite size, particularly under seawater conditions. These structural differences were quantified using Rietveld refinement of the diffraction data. The structural evolution of microfibers under environmentally relevant conditions has direct implications for their fragmentation potential, persistence, and the release or transport of adsorbed contaminants. The results underscore the importance of considering material-specific behaviors in assessing environmental persistence and potential ecological impact.
微纤维是日益受到关注的污染物，因为它们会在水生环境中积累并对生物构成风险。一旦释放，它们会经历降解过程，从而减小尺寸并增强其与生物系统相互作用的能力。在这些过程中，光降解是一个关键驱动因素，会导致纤维破碎和结构收缩。本研究调查了五种常见微纤维（棉、醋酸纤维素、聚酰胺、聚酯和亚麻）在模拟相当于一年环境条件的太阳紫外线照射下，分散在海水和淡水中时的纳米结构演变。使用基于同步加速器的小角和广角X射线散射技术，我们对纤维内部结构的变化进行了表征。小角X射线散射数据使用多尺度模型进行分析，该模型将大纤维描述为由排列在扭曲六方晶格中的多分散核壳微纤维束组成。结果揭示了明显的纳米结构变化。在海水中，棉和聚酰胺的微纤维间距增加，导致大纤维增大，而在淡水中它们的结构保持更稳定或不规则演变。聚酯和亚麻在两种介质中均显示大纤维直径逐渐减小，表明其破碎趋势更大。醋酸纤维素在海水中结构保持稳定，但在淡水中会发生收缩和部分重组。广角X射线散射证实了棉、亚麻和聚酰胺中存在晶相，并揭示了微晶尺寸的介质特异性变化，特别是在海水条件下。这些结构差异通过对衍射数据的Rietveld精修进行了量化。微纤维在环境相关条件下的结构演变对其破碎潜力、持久性以及吸附污染物的释放或传输具有直接影响。结果强调了在评估环境持久性和潜在生态影响时考虑材料特定行为的重要性。
