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

LeBoeuf和Li1133280和1133528这项由环境健康与安全纳米技术计划颁发的NSF奖支持范德比尔特大学的Eugene J.LeBoeuf教授以及内布拉斯加大学林肯分校的李宇松和陆永峰教授的工作，他们研究附着相有机物对碳基纳米材料在多孔介质中的命运、传输和移除的影响。扩大生产并随后将工程纳米材料(ENM)纳入消费产品会增加释放到环境中的可能性。通常，随着时间的推移，疏水颗粒化合物会在有机系统中积累，包括附着相土壤和沉积物有机质(AP-SOM)。尤其是在沉积物中，污染物有可能在相当长的一段时间内持续存在；因此，ENMS可能会对未来很长一段时间的环境产生影响。尽管已有一些研究致力于研究ENM在环境中的行为，但很少有研究集中在AP-SOM和ENM之间的相互作用。本研究的目标是建立系统的、机械性的理解ENM和AP-SOM之间的相互作用及其对ENM运输的影响。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、球形和洋葱形状的体系，从而专注于碳基ENM。同时，选择腐植酸和干酪根来代表软/年轻和硬/老的AP-SOM。中心假设是ENM聚集体与AP-SOM之间的相互作用受ENM的基本纳米结构(例如，不同形状)和AP-SOM的物理化学特性(例如，大分子橡胶/玻璃态)的影响。本文围绕四个目标构建了一个完整的实验和模拟研究框架：(1)表征SOM和ENM，将AP-SOM和ENM的基本纳米结构与它们的宏观相互作用联系起来；(2)通过进行石英晶体微天平(QCM)附着/分离实验来量化纳米材料与AP-SOM的相互作用；(3)通过柱实验来量化AP-SOM对纳米材料在多孔介质中传输的影响；以及(4)建立并实验验证一个能够模拟AP-SOM存在下纳米材料在多孔介质中传输的数学模型。这项拟议的研究可能具有变革性，因为它旨在将基本纳米结构和性质与ENM聚集传输行为联系起来，特别关注AP-SOM的存在。随着纳米材料的研究和生产速度不断加快，迫切需要对这些材料的环境影响进行全面研究。了解纳米材料在多孔介质中的命运和传输将提供有关工程纳米材料对生态系统和人类健康影响的关键信息。根据这一建议开发的数值模拟器可以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、基于风险的指南，以解决这些新出现的污染物。我们在纳米颗粒在多孔介质中保留的基础知识方面的进展也可以用来模拟过滤技术的性能，以处理含有纳米颗粒的饮用水或废水。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，方法是让代表人数不足的群体参与该项目，并将研究成果转移到课堂上。这项工作产生的基本知识、实验技术和建模工具将以期刊出版物和在区域、国家和国际专业会议上发表演讲的形式迅速传播给科学界。

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.