Abstract：
Expanded polystyrene (EPS) plastic is widely used because of its low density and lightweight properties, enabling it to float on water and increase its exposure to sunlight. In this study, we simulated the photoaging process of flame retardant-added EPS (FR-EPS) and common original EPS (OR-EPS) microplastic (MP) particles with and without methyl octabromoether flame retardant (MOBE) in the laboratory to explore the effect of MOBE on the photodegradation of EPS. Results showed that MOBE accelerated size reduction and surface hole formation on the particles, hastening the shedding and replacement of particle surfaces. FR-EPS particles exhibited a weight loss exceeding that of OR-EPS, reaching 40.85 ± 3.72% after 36 days of irradiation. Moreover, rapid physical peeling of the FR-EPS surface was accompanied by continuous chemical oxidation and fluctuations of the carbonyl index and O/C ratio. A diffusion model based on Fick\'s second law fitted well for the concentration of MOBE remaining in FR-EPS particles. MOBE\'s sensitivity to direct photochemical reactions inhibited the early-stage photoaging of EPS MP particles by competing for photons. However, MOBE as chromophores could absorb photons and produce •OH to promote the aging of EPS. Moreover, the capacity of EPS to absorb light energy also accelerated MOBE degradation. These findings suggested that the photoaging behavior of commercial EPS products containing flame retardants in the environment is quite different from that of pure EPS, indicating that additive-plastic interactions significantly alter MP fate and environmental risks.
摘要：
可膨胀聚苯乙烯（EPS）塑料由于其低密度和轻质性能而被广泛使用，使它能够漂浮在水面上，增加阳光照射。在这项研究中,我们在实验室中模拟了添加阻燃剂的EPS（FR-EPS）和普通原始EPS（OR-EPS）微塑料（MP）颗粒在添加和不添加甲基八溴醚阻燃剂（MOBE）的光老化过程，以探讨MOBE对EPS光降解的影响。结果表明，MOBE加速了颗粒的尺寸减小和表面孔洞的形成，加快颗粒表面的脱落和更换。FR-EPS颗粒表现出超过OR-EPS的重量损失，照射36天后达到40.85±3.72%。此外，FR-EPS表面的快速物理剥离伴随着连续的化学氧化以及羰基指数和O/C比的波动。基于Fick第二定律的扩散模型很好地拟合了FR-EPS颗粒中残留的MOBE浓度。MOBE对直接光化学反应的敏感性通过竞争光子来抑制EPSMP颗粒的早期光老化。然而,MOBE作为发色团可以吸收光子并产生·OH以促进EPS的老化。此外，EPS吸收光能的能力也加速了MOBE的降解。这些发现表明，含有阻燃剂的市售EPS产品在环境中的光老化行为与纯EPS有很大不同，表明添加剂-塑料相互作用显著改变MP命运和环境风险。
