Collaborative Research: Real-time Investigations of Anisotropic Nanoparticle Aggregation and Consequences for Deposition in Porous Media

合作研究：各向异性纳米颗粒聚集及其在多孔介质中沉积的后果的实时研究

• 批准号: 1836799
• 负责人: Yusong Li
• 金额: $ 23万
• 依托单位: University of Nebraska-Lincoln
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1836799&HistoricalAwards=false
• 关键词: Collaborative; Research; Real; time; Investigations

Nanoparticles are prevalent in nature and widely produced in a variety of shapes and sizes in ever-increasing quantities. These nanoparticles often aggregate in water, and thus they typically transport and deposit in environmental media in the form of aggregates instead of individual nanoparticles. However, how the structure of nanoparticle aggregates influence nanoparticles' movement in the environment is not well understood. The overall objective of this project is to better understand the interactions of nanoparticulate aggregates with environmental media and how these interactions can be governed by the shape and size of the individual nanoparticles. Findings from this work can benefit the design and optimization of a broad range of engineered processes, such as filter-based water treatment, groundwater remediation, and drug delivery. This project will also benefit K-12 education through outreach activities involving videos and pictures of nanomaterials. Additional outreach programs include 1) the Summer Coding Camp, at Ohio University to introduce middle school girls to the STEM fields, and 2) various science activities offered by Nebraska Center for Materials and Nanosciences at the University of Nebraska-Lincoln to broaden the exposure of K-12 students to materials science and engineering, nanoscience, and nanotechnology. In addition, the PIs will leverage the existing REU programs at the University of Nebraska-Lincoln to train Ohio university undergraduate students during summers. In the past, nanoparticle aggregation and deposition were often studied separately, with limited research linking mobility of nanoparticles in environmental media to the structure of nanoparticle aggregates. However, new evidence suggests that anisotropic nanoparticles, the most common form of nanoparticles in the environment, often form non-compact aggregates. The formation of these non-compact aggregates cannot be explained by classic colloidal aggregation theories. Moreover, non-compact aggregates undergo unusual deposition and modify hydrodynamics in environmental porous media, which is not described by the classical filtration theory. Acquisition and integration of quantitative data from all steps involved in nanoparticle aggregation and deposition is critically needed. The research objectives of this project include: 1) Quantifying the anisotropic diffusion dynamics of nanoparticles with various aspect ratios in water; 2) Elucidating the role of the shape of primary nanoparticles on the formation kinetics and morphological structure of aggregates; and 3) Evaluating the impact of aggregate structure on the transport and deposition of aggregates in environmental porous media. Hematite nanoparticles with different aspect ratios (i.e., nanosphere, nanorod, nanodisk) will be synthesized in the study. Advanced techniques will be employed to visualize and quantify nanoparticle diffusion, aggregation, transport, and deposition in environmental matrices. Furthermore, the experimental data will be used to update classical filtration theory for predicting nanoparticle behaviors in porous media. The expected intellectual outcomes from this work will include development of a series of quantitative metrics from measurements of anisotropic diffusion, aggregate formation, and aggregate deposition and flow dynamics in porous media. These quantitative characterizations will allow us to elucidate the mechanisms which control anisotropic nanoparticle aggregation and deposition in environmental porous media. This will, in turn, improve the utility of colloidal science principles in understanding and predicting nanoparticle behaviors, such as colloid Brownian motion theory, colloid aggregation theory, and the classical filtration theory.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.

纳米颗粒在本质上是普遍的，并以多种形状和大小的数量广泛产生。这些纳米颗粒通常聚集在水中，因此它们通常以聚集体而不是单个纳米颗粒的形式运输和沉积。但是，纳米粒子聚集的结构如何影响纳米颗粒在环境中的运动。该项目的总体目的是更好地了解纳米标志骨料与环境媒体的相互作用，以及如何通过单个纳米颗粒的形状和大小来支配这些相互作用。这项工作的发现可以使广泛工程过程的设计和优化受益，例如基于滤波器的水处理，地下水补救和药物输送。该项目还将通过涉及纳米材料的视频和图片的外展活动来使K-12教育受益。其他外展计划包括1）俄亥俄州大学的夏季编码营地，向中学女生介绍STEM领域，以及2）内布拉斯加州内布拉斯加州材料和纳米科学中心提供的各种科学活动。此外，PIS将利用内布拉斯加州林肯大学的现有REU计划在夏季培训俄亥俄州大学的本科生。过去，经常研究纳米颗粒的聚集和沉积，而有限的研究将环境介质中纳米颗粒的迁移率与纳米颗粒聚集体的结构联系起来。然而，新的证据表明，各向异性纳米颗粒是环境中最常见的纳米颗粒形式，通常形成非压缩聚集体。这些非压缩聚集体的形成不能用经典的胶体聚集理论来解释。此外，非紧密的聚集体会在环境多孔培养基中经历异常的沉积并修改流体动力学，而经典过滤理论未描述。从纳米颗粒聚集和沉积中涉及的所有步骤中获取和集成定量数据是至关重要的。该项目的研究目标包括：1）量化水中各种宽高比的纳米颗粒的各向异性扩散动力学； 2）阐明原代纳米颗粒形状对骨料的形成动力学和形态结构的作用； 3）评估骨料结构对环境多孔培养基中聚集体的运输和沉积的影响。该研究将在研究中合成具有不同宽高比（即纳米球，纳米棒，纳米棒）的血液纳米颗粒。高级技术将用于可视化和量化环境矩阵中的纳米颗粒扩散，聚集，运输和沉积。此外，实验数据将用于更新经典的过滤理论，以预测多孔培养基中的纳米颗粒行为。这项工作的预期智力结果将包括从各向异性扩散，骨料形成以及多孔培养基中的聚集沉积和流动动力学来开发一系列定量指标。这些定量特征将使我们能够阐明控制环境多孔培养基中各向异性纳米颗粒聚集和沉积的机制。反过来，这将改善胶体科学原则在理解和预测纳米颗粒行为方面的实用性，例如胶体布朗运动理论，胶体聚集理论和经典过滤理论。该奖项反映了NSF的法定任务，并被认为是通过基金会的知识优点和广泛的范围来评估的。