Collaborative Research: A Multiscale Framework to Investigate the Influence of Attached Phase Soil Organic Matter on the Fate, Transport, and Removal of Carbon-based Nanomaterials

这项由纳米技术的环境健康与安全项目授予的国家科学基金会奖支持范德比尔特大学的Eugene J. LeBoeuf教授和林肯内布拉斯加州大学的李玉松教授和卢永峰教授的工作，他们研究了附着相有机物对多孔介质中碳基纳米材料的命运、运输和去除的影响。不断升级的生产和随后在消费品中加入工程纳米材料（enm）增加了向环境释放的可能性。通常，随着时间的推移，释放的疏水颗粒化合物会积聚在有机系统中，包括附着相土壤和沉积物有机质（AP-SOM）。特别是在沉积物中，污染物有可能持续很长一段时间；因此，能源管理可能会在未来很长一段时间内影响环境。虽然已经有一些研究致力于研究ENM在环境中的行为，但很少有研究关注AP-SOM和ENM的相互作用。本提案的目标是建立系统的、机制的理解ENM和AP-SOM之间的相互作用及其对ENM转运的影响。我们通过选择多壁碳纳米管（MWCNT）、富勒烯（C60）和碳纳米洋葱（CNOs）来代表圆柱形、球形和洋葱形体系来关注碳基enm。同时，腐植酸和干酪根分别代表柔软/年轻和坚硬/年老的AP-SOM。核心假设是ENM聚集体与AP-SOM之间的相互作用受到ENM的基本纳米结构（如不同形状）和AP-SOM的物理化学特性（如大分子橡胶/玻璃态）的影响。围绕以下四个目标构建了一个集成的实验和建模研究框架：(1)表征SOM和ENM，将AP-SOM的物理化学和大分子特征与ENM的基本纳米结构及其宏观相互作用联系起来；(2)通过石英晶体微天平（Quartz Crystal Microbalance， QCM）的附着/剥离实验，量化纳米材料与AP-SOM的相互作用；(3)通过柱实验量化AP-SOM对纳米材料在多孔介质中输运的影响；(4)建立并实验验证了一个能够模拟AP-SOM存在时纳米材料在多孔介质中传输的数学模型。这项提议的研究可能具有变革性，因为它旨在将基本的纳米结构和性质与ENM聚集体输运行为联系起来，特别关注AP-SOM的存在。随着纳米材料研究和生产的步伐不断加快，迫切需要对这些材料的环境影响进行全面的研究。了解纳米材料在多孔介质中的命运和运输将为工程纳米材料对生态系统和人类健康的影响提供关键信息。根据该建议开发的数值模拟器可用于预测工程纳米材料在一系列环境条件下的迁移距离，这可以帮助监管机构制定改进的、基于风险的指导方针，以解决这些新出现的污染物。纳米颗粒在多孔介质中保留的基础知识的进步也可以用来模拟过滤技术处理含有纳米颗粒的饮用水或废水的性能。通过将代表性不足的群体纳入项目并将研究成果转化为课堂，该项目将在激励STEM领域的本科生和毕业生方面取得重大进展。从这项工作中产生的基础知识、实验技术和建模工具将以期刊出版物和在地区、国家和国际专业会议上的报告的形式迅速传播到科学界。

Collaborative LeBoeuf and Li1133280 and 1133528This NSF award by the Environmental Health and Safety of Nanotechnology program supports work by Professor Eugene J. LeBoeuf at Vanderbilt University, and Professors Yusong Li and Yongfeng Lu at the University of Nebraska , Lincoln to investigate the influence of attached phase organic matter on the fate, transport and removal of carbon-based nanomaterials in porous media.Escalating production and subsequent incorporation of engineered nanomaterials (ENMs) in consumer products increases the likelihood of release to the environment. Typically, hydrophobic particulate compounds released over time will accumulate in organic systems, including attached phase soil and sediment organic matter (AP-SOM). Especially in sediments, there is the potential for contaminants to persist for significant periods of time; therefore ENMs may impact environments long into the future. Although some effort has been devoted to investigate the behavior of ENMs in the environment, a very limited number of studies have focused on the interactions of AP-SOM and ENM.The goal of this proposal is to build systematic, mechanistic understanding of the interactions between ENM and AP-SOM and their influence on ENM transport. We focus on carbon-based ENMs by selecting multi-walled carbon nanotubes (MWCNT), fullerene (C60), and carbon nano-onions (CNOs) to represent cylindrical, spherical, and onion-shaped systems. Meanwhile, humic acid and kerogen are selected to represent soft/young and rigid/old AP-SOM. The central hypothesis is that the interactions between ENM aggregates and AP-SOM are affected by the fundamental nanostructure (e.g., different shapes) of ENMs and physicochemical characteristics (e.g., macromolecular rubbery/glassy states) of AP- SOM. An integrated experimental and modeling research framework is structured around four objectives: (1) Characterize SOM and ENMs to link physicochemical and macromolecular characteristics of AP-SOM and the fundamental nanostructure of ENM with their macroscopic interactions; (2) Quantify the interactions of nanomaterials and AP-SOM by conducting Quartz Crystal Microbalance (QCM) attachment/detachment experiments; (3) Quantify the influence of AP-SOM on the transport of nanomaterials in porous media by conducting column experiments; and (4) Develop and experimentally validate a mathematical model that is capable of simulating nanomaterial transport in porous media in the presence of AP-SOM. The proposed research can be transformative because it aims to link fundamental nanostructure and properties to the behaviors of ENM aggregate transport, with a particular focus on the presence of AP-SOM.As the pace of research and production of nanomaterials continues to increase, comprehensive studies on the environmental impact of these materials are urgently needed. Understanding the fate and transport of nanomaterials in porous media will provide critical information on the influence of engineered nanomaterials on ecosystems and human health. The numerical simulator developed from this proposal can be used to predict the mobility distance of engineered nanomaterials under a range of environmental conditions, which can assist regulatory agencies in developing improved, risk-based guidelines that address these emerging contaminants. The advancement in our fundamental knowledge of nanoparticle retention in porous media can also be used to model the performance of filtration technologies for treatment of drinking water or wastewater containing nanoparticles. The project will initiate significant advancements in motivating undergraduates and graduates in the STEM areas by involving underrepresented groups in the project and transferring research results into the classroom. The fundamental knowledge, experimental techniques, and modeling tools produced from this work will be rapidly disseminated to the scientific community in the form of journal publications and presentations at regional, national, and international professional meetings.