In this study, polyethylene microplastics were artificially photoaged by xenon light. Experiments were then performed with methylene blue (MB) dye to compare the changes in the structure, properties, and adsorption–desorption behaviors of the aged and virgin polyethylene microplastics. The results showed that the aged polyethylene microplastics were hydrophilic with oxygen-containing functional groups, which enhanced the adsorption capacity of polyethylene for MB from 0.63 mg·g⁻¹ to 8.12 mg·g⁻¹. The adsorption isotherms changed from the Henry model (virgin polyethylene microplastics) to the Langmuir model (aged polyethylene microplastics), indicating that the partitioning function was gradually replaced by a single-layer covering during the adsorption process. In addition, 7% and 17.8% of the MB loaded onto the aged polyethylene microplastics was desorbed into water and a simulated intestinal fluid, respectively. These findings reveal that aged polyethylene microplastics can accumulate MB, thus posing potential risks to aqueous environments and biological tissues.

在这项研究中，聚乙烯微塑料被氙气人工光老化。然后，用亚甲基蓝（MB）染料进行了实验，比较了老化的和原始的聚乙烯微塑料的结构，性质和吸附-脱附行为的变化。结果表明，老化的聚乙烯微塑料具有带氧官能团的亲水性，将聚乙烯对MB的吸附能力从0.63 mg·g ^-1提高到8.12 mg·g ^-1。吸附等温线从亨利模型（原始聚乙烯微塑料）变为朗格缪尔模型（老化的聚乙烯微塑料），表明在吸附过程中分配功能逐渐被单层覆盖物取代。此外，分别加载到老化的聚乙烯微塑料上的MB的7％和17.8％分别被解吸到水和模拟的肠液中。这些发现表明，老化的聚乙烯微塑料会积聚MB，从而对水环境和生物组织构成潜在风险。