CAS-MNP: Molecular Probing Surface Reactivity Dynamics of Native versus Photo-Oxidized Microplastics and Nanoplastics in Environmental Aqueous Media

化学系环境化学科学计划和化学，生物，环境和运输系统系环境工程计划的这一奖项支持西北大学的Ludmilla Aristilde博士研究微塑料和纳米塑料，这是塑料在海洋，湖泊和河流中的环境命运的重要最终产品。据报道，这些残留的塑料材料在不同的环境水介质中捕获各种有机污染物。由于暴露在阳光下的反应性颗粒的存在，通过光氧化，破碎的塑料表面可以开发不同的化学特性。该项目的重点是解开这些不同的化学特性及其在促进污染物吸附在聚乙烯，聚丙烯和聚苯乙烯塑料类型的作用。推广和教育更广泛的影响，旨在实施本科生到研究活动，促进高中生的参与，并提高公众对塑料废物的环境命运的认识。该项目采用了几种光谱研究，结合分子模拟，以揭示天然与光化学的表面化学和化学动力学，微塑料和纳米塑料的氧化结构与其与特定污染物类别的选择性相互作用有关。塑料的吸附作用依赖于水-塑料界面处有利的纳米级到分子级的相互作用。然而，对这些相互作用的机械理解，特别是在原生塑料与光氧化塑料的不同表面化学的背景下，仍然是一个关键的知识差距。原子尺度的实验探测在水-塑料界面环境进行，以阐明在不同的介质组合物中的分子反应性的变化，代表淡水与海水的不同化学物质。这些实验结果与溶剂化系统的分子建模模拟相结合，以确定控制有利的与不利的污染物对原生与光老化纳米塑料表面的亲和力的结构因素。该研究有望为微塑料和纳米塑料表面的结构和化学变化如何影响水-塑料界面上不同类别有机污染物的捕获动力学提供新的机理见解。这些发现对于开发微塑料和纳米塑料在淡水和海洋沃茨中有机污染物命运中的作用的预测模型非常重要。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

This award from the Environmental Chemical Sciences Program in the Division of Chemistry and the Environmental Engineering Program in the Division of Chemical, Biological, Environmental, and Transport Systems is supporting Dr. Ludmilla Aristilde at Northwestern University for research on microplastics and nanoplastics, which are important end-products in the environmental fate of plastics in oceans, lakes, and rivers. These remnant plastic materials are reported to trap various organic contaminants in different environmental aqueous media. Through photo-oxidation due to exposure to sunlight in the presence of reactive particles, the fragmented plastic surfaces can develop different chemical characteristics. This project focuses on unraveling these different chemical characteristics and their role in facilitating contaminant adsorption on the polyethylene, polypropylene, and polystyrene plastic types. The outreach and educational broader impacts aim to implement undergraduate students into the research activities, foster the engagement of high school students, and increase public literacy regarding the environmental fates of plastic wastes.This project applies several spectroscopic investigations coupled with molecular simulations to unravel the surface chemistry and chemical dynamics at native versus photo-oxidized structures of microplastics and nanoplastics in relation to their selective interactions with specific contaminant classes. The adsorbent role of plastics relies on favorable nanoscale to molecular-scale interactions at the water-plastic interfaces. However, a mechanistic understanding of these interactions, especially within the context of the different surface chemistries of native versus photo-oxidized plastics, remains a critical knowledge gap. Atomistic-scale experimental probing at the water-plastic interfacial environments is performed to elucidate changes in molecular reactivity in different media composition representing freshwater versus seawater of varying chemistries. These experimental results are coupled with molecular modeling simulations of solvated systems to determine the structural factors that control favorable versus unfavorable contaminant affinity to native versus photo-aged nanoplastic surfaces. The research is expected to provide new mechanistic insights on how structural and chemical changes at the microplastic and nanoplastic surfaces influence the trapping dynamics of organic contaminants of different classes at the water-plastic interface. These findings will be important in the quest to develop predictive models for the role of microplastics and nanoplastics in the fate of organic contaminants in freshwater and marine waters.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.