RUI: CAS-MNP: Molecular Behavior at Colloidal/Aqueous Interfaces of Heterogeneous Nano- and Micro-Plastics - Binding Interactions and Effect of Aging

在化学学部环境化学科学项目的支持下，Mahamud Subir和他在波尔州立大学的研究生和本科生团队将进行表面选择性二次谐波产生（SHG）光谱和石英晶体微平衡技术，目的是确定与各种类型的微和纳米塑料（MNPs）有关的吸附参数。塑料污染已成为一个主要的环境问题。在水生环境中，塑料可以分解并形成大小从几纳米到数百微米不等的小碎片。这些微和纳米塑料（MNP）颗粒提供了一个大的表面积，这使得其他有机污染物溶解在水中，与MNP表面相互作用。了解这些结合相互作用非常重要，因为它们决定了MNPs和有机污染物的命运和运输性质。此外，阐明MNPs的表面亲和性对于开发有效的吸附技术来去除微塑料至关重要。本项目将研究不同类型的有机化合物与不同组成和表面性质的MNPs的表面相互作用。该项目不仅将产生关于MNPs在有机分子存在下的结合行为的新知识，而且还将培养未来的科学家应对与塑料污染相关的持续挑战。MNPs是异质的，其界面化学是复杂的。因此，将采用表面选择性二次谐波产生（SHG）光谱和石英晶体微平衡技术进行系统研究，以确定与各种MNPs相关的吸附热力学和动力学参数。吸附研究将使用带电和中性SHG探针分子进行。温度依赖性吸附研究有望揭示它们与MNP/水界面相互作用的结合强度和机制。总之，这些实验有可能帮助建立MNPs表面官能团和结合相互作用之间的关系。非特异性与特异性结合相互作用的作用将被检查。其他目标包括研究MNP老化及其大小和形状对分子结合的影响。从长远来看，确定有机化合物吸附强度与MNPs化学特性之间的相关性有望为改进这些新出现的水生污染物的命运和运输建模提供基础。该奖项反映了美国国家科学基金会的法定使命，并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，被认为值得支持。

With support from the Environmental Chemical Sciences Program in the Division of Chemistry, Mahamud Subir and his team of graduate and undergraduate students at Ball State University will perform surface-selective second harmonic generation (SHG) spectroscopy and quartz crystal microbalance technology with the aim of determining the adsorption parameters pertaining to various types of micro- and nano-plastics (MNPs). Plastic pollution has become a major environmental concern. In the aquatic environment, plastics can break down and form small fragments ranging from a few nanometers to hundreds of micrometers in size. These micro- and nano-plastic (MNP) particles offer a large surface area, which allows other organic contaminants dissolved in water, to interact with the MNP surfaces. Understanding these binding interactions is important as they determine the fate and transport properties of both MNPs and organic pollutants. Moreover, elucidating the surface affinities of MNPs is critical in developing effective adsorption techniques to remove microplastics. In this project, surface interactions of different types of organic compounds with MNPs of various compositions and surface properties will be investigated. The project will not only generate new knowledge on the binding behavior of MNPs in the presence of organic molecules, but also train future scientists in tackling persistent challenges associated with plastics pollution. MNPs are heterogeneous and their interfacial chemistry is complex. Therefore, a systematic investigation using surface-selective second harmonic generation (SHG) spectroscopy and quartz crystal microbalance technology will be performed to determine the adsorption thermodynamic and kinetic parameters pertaining to various types of MNPs. The adsorption studies will be conducted using charged and neutral SHG probe molecules. Temperature-dependent adsorption studies are expected to reveal the binding strengths and mechanisms of their interaction with MNP/aqueous interfaces. Together, these experiments have the potential to help establish relationships between surface functional groups of MNPs and binding interactions. The role of non-specific vs. specific binding interactions will be examined. Additional objectives include investigating the impact of MNP ageing and of their size and shape on molecular binding. Determining a correlation between organic compound adsorption strength and chemical characteristics of MNPs has the potential, in the longer term, is expected to provide a foundation for improved modeling of the fate and transport of these emerging aquatic contaminants.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.