Wieland Markus A B, Schwaminger Sebastian P, Elinkmann Matthias, Stüger Paul M, Feldmann Jörg, Clases David, Gonzalez de Vega Raquel
NanoMicroLab, Institute of Chemistry, University of Graz Graz Austria.
Institute of Inorganic and Analytical Chemistry, University of Münster Münster Germany.
J Anal At Spectrom. 2025 Sep 2. doi: 10.1039/d5ja00226e.
Advanced oxidation processes (AOPs) are increasingly adopted in wastewater treatment to degrade persistent pollutants, including emerging targets such as microplastics (MPs). These particles enter aquatic systems through the fragmentation of bulk plastics and, as their size decreases, exhibit enhanced mobility, surface reactivity, and biological uptake potential. However, the efficiency of AOPs in removing MPs and their nanoscale derivatives (nanoplastics, NPs) remains poorly understood, partly due to the lack of suitable analytical tools. Small MPs and NPs often occur at trace levels and are obscured by colloidal and dissolved background in complex matrices. Moreover, growing evidence suggests that AOPs may promote fragmentation rather than complete degradation. Thus, the focus of this study is to investigate ozone as a reactive agent for MP degradation, using single-particle inductively coupled plasma - mass spectrometry (SP ICP-MS). The formation of nanoscale plastics was qualitatively assessed using dynamic light scattering (DLS). The degradation behaviour of primary MPs such as polystyrene (PS) and polytetrafluoroethylene (PTFE), and secondary MPs generated from bulk poly(methyl methacrylate) (PMMA) and polyvinyl chloride (PVC) was assessed. Ozone exposure led to progressive mass reduction for PS and PMMA, while PTFE and PVC showed greater oxidation resistance. SP ICP-MS revealed detailed transformations in mass, which were projected into size distributions, while DLS confirmed the formation of nanoscale particles in all cases. These findings highlight that ozone-based AOPs can promote nanoplastic formation, underscoring the need to evaluate treatment efficiency not only by particle removal but also with regard to the nature and behaviour of transformation products. The combined use of SP ICP-MS and DLS offers unique insights into MP degradation and the unintended formation of NPs during oxidative treatment, an aspect of particular relevance as AOPs are increasingly integrated into wastewater treatment under the revised European Urban Wastewater Treatment Directive (2024/3019).
高级氧化工艺（AOPs）在废水处理中越来越多地被用于降解持久性污染物，包括微塑料（MPs）等新出现的目标污染物。这些颗粒通过大块塑料的破碎进入水生系统，随着其尺寸减小，表现出更高的迁移率、表面反应性和生物摄取潜力。然而，AOPs去除MPs及其纳米级衍生物（纳米塑料，NPs）的效率仍知之甚少，部分原因是缺乏合适的分析工具。小尺寸的MPs和NPs通常以痕量水平存在，并且在复杂基质中被胶体和溶解的背景所掩盖。此外，越来越多的证据表明，AOPs可能促进破碎而不是完全降解。因此，本研究的重点是使用单颗粒电感耦合等离子体质谱（SP ICP-MS）研究臭氧作为MP降解的反应剂。使用动态光散射（DLS）对纳米级塑料的形成进行定性评估。评估了聚苯乙烯（PS）和聚四氟乙烯（PTFE）等原生MPs以及由大块聚甲基丙烯酸甲酯（PMMA）和聚氯乙烯（PVC）产生的次生MPs的降解行为。臭氧暴露导致PS和PMMA的质量逐渐减少，而PTFE和PVC表现出更高的抗氧化性。SP ICP-MS揭示了质量的详细变化，并将其投影到尺寸分布中，而DLS证实了在所有情况下都形成了纳米级颗粒。这些发现突出表明，基于臭氧的AOPs可以促进纳米塑料的形成，强调不仅需要通过颗粒去除来评估处理效率，还需要考虑转化产物的性质和行为。SP ICP-MS和DLS的联合使用为MP降解以及氧化处理过程中NPs的意外形成提供了独特的见解，随着AOPs根据修订后的欧洲城市污水处理指令（2024/3019）越来越多地被纳入污水处理，这一方面具有特别的相关性。
