微塑料,特别是微纤维(MF),对环境构成重大威胁。尽管他们广泛存在,光化学反应性,耐候产品,对MFs的环境命运仍然知之甚少。为了解决这个知识差距,在三种常见的MF上进行了光降解实验:聚酯(POL),尼龙(NYL),和丙烯酸(ACR),阐明它们的降解途径,表面形态和聚合物结构的变化,以及MFs光化学降解过程中风化产物的化学和胶体表征。结果表明,溶解有机碳的浓度,发色溶解有机物(DOM),在风化过程中荧光成分不断增加,表现出DOM的持续释放。扫描电子显微镜和拉曼光谱揭示了MF的表面形态和聚合物光谱的变化。在风化实验中,DOM芳香性(SUVA254)下降,当光谱斜率增加时,表明同时释放DOM和降解芳香成分。释放的DOM或纳米塑料带负电荷,尺寸在128至374nm之间。DOM的生产率常数或MF的光化学反应性遵循ACR>NYL≥POL的顺序,与它们在化学结构上的差异一致。这些发现提供了一个更好的理解光化学反应,降解途径,耐候产品,以及微纤维在环境中的环境命运。
Microplastics, particularly microfibers (MFs), pose a significant threat to the environment. Despite their widespread presence, the photochemical reactivity, weathering products, and environmental fate of MFs remain poorly understood. To address this knowledge gap, photodegradation experiments were conducted on three prevalent MFs: polyester (POL), nylon (NYL), and acrylic (ACR), to elucidate their degradation pathways, changes in surface morphology and polymer structure, and chemical and colloidal characterization of weathering products during photochemical degradation of MFs. The results showed that concentrations of dissolved organic carbon, chromophoric dissolved organic matter (DOM), and fluorescent components consistently increased during weathering, exhibiting a continuous release of DOM. Scanning electron microscopy and Raman spectroscopy revealed changes in the surface morphology and polymer spectra of the MFs. During the weathering experiments, DOM aromaticity (SUVA254) decreased, while spectral slope increased, indicating concurrent DOM release and degradation of aromatic components. The released DOM or
nanoplastics were negatively charged with sizes between 128 and 374 nm. The production rate constants of DOM or the photochemical reactivity of MFs followed the order ACR > NYL ≥ POL, consistent with their differences in chemical structures. These findings provide an improved understanding of the photochemical reactivity, degradation pathways, weathering products, and environmental fate of microfibers in the environment.