CAREER: An Integrated Environmental Engineering Education and Research Plan to Enhance Molecular-Level Understanding of Sequestration Behavior of Volatile Organic Compounds

9985159勒博夫修复被挥发性有机化合物(VOC)污染的地下场地花费了国家数十亿美元。将基于风险的方法应用于受污染场地的评估，需要准确了解控制污染物在环境中的传输和释放的机制。这项研究解决了这一问题，为从分子水平上更好地理解地下VOCs的封存机制提供了基础。其目的是：(1)确定自然有机质组成对VOC吸附和解吸行为的影响；(2)确定土壤和沉积物纳米孔对VOC吸附和解吸行为的影响；(3)根据土壤和沉积物的功能和结构特征预测VOC吸附和解吸行为；(4)利用交互式教学技术调查课堂中的传质原理；(5)确定土壤和沉积物的功能和结构特征如何影响VOC去向和迁移的现场尺度评估。通过对天然有机物(NOM)的功能和结构特征的研究，可以了解控制有机污染物在地下的去向和迁移的封存过程。温度调制差示扫描量热法将用于研究纳米有机蒙脱土的玻璃化转变、热容和热焓松弛行为。这些信息将提供对其结构和固有的大分子流动性的见解。使用正电子湮没寿命谱(PALS)探测纳米孔的大小、体积和疏水性，将提供一种改进的手段来关联纳米孔结构与土壤和沉积物中VOC的固定行为。将PALS测量与基于氮气、Ar和二氧化碳的气体吸附数据进行比较，将增加对普通基于气体的测量能力的了解，以表征NOM、模型土壤以及整个土壤和沉积物的纳米孔隙度。通过开发用户友好的、基于图形用户界面的有限元和有限差分传质模型，将使存在橡胶或玻璃态的NOM和纳米孔对VOC传输的影响变得生动起来。将这一模型与已开发的案例研究结合使用，将提供一个积极的学习环境，强调使用基本概念来更准确地预测现实世界中的污染物行为。案例研究、实地考察和实习工程师的访问将为学生提供与现实世界问题的联系。与田纳西州立大学的合作将为本科生提供接触研究生水平研究的机会，而与橡树岭国家实验室的合作将显著增加本科生和研究生的研究机会。***

9985159 LeBoeuf Remediation of subsurface sites contaminated with volatile organic compounds (VOCs) costs the nation billions of dollars. The application of risk based approaches to the evaluation of contaminated sites requires an accurate understanding of the mechanisms controlling the transport and release of contaminants in the environment. This research addresses this issue by providing a basis for an improved molecular-level understanding of the mechanisms responsible for the sequestration of VOCs in the subsurface. The objectives are to: (1) determine the effects of natural organic matter composition on VOC sorption and desorption behavior; (2) determine the effects of soil and sediment nanoporosity on VOC sorption and desorption behavior; (3) predict VOC sorption and desorption behavior based on functional and structural characteristics of soils and sediments; (4) investigate mass transfer principles in the classroom using interactive teaching techniques and (5) determine how soil and sediment functional and structural characteristics affect field-scale evaluation of VOC fate and transport. An investigation of the functional and structural characteristics of natural organic matter (NOM) is used to understand the sequestration processes that control the fate and transport of organic contaminants in the subsurface. Temperature-modulated differential scanning calorimetry will be used to investigate glass transition, heat capacity and enthalpic relaxation behavior of NOMs. This information will provide insights to its structure and inherent macromolecular mobility. Use of positron annihilation lifetime spectroscopy (PALS) to probe the size, volume and hydrophobicity of NOM nanopores will provide an improved means to correlate nanopore structure with VOC sequestration behavior in soils and sediments. Comparisons of PALS measurements with N2, Ar and CO2 gas-based sorption data will provide increased knowledge of the ability of common gas-based measurements to characterize the nanoporosity of NOMs, model soils, and whole soils and sediments. The effects of the presence of a rubbery or glassy state of NOM and nanoporosity on VOC transport will be brought to life through development of a user-friendly, graphical-user-interface based finite element and finte difference mass transfer model. The use of this model in conjunction with developed case studies will provide an active learning environment emphasizing the use of fundamental concepts to more accurately predict contaminant behavior in real-world situations. Case studies, field trips and visits by practicing engineers will provide students a connection with real-world problems. Partnerships with Tennessee State University will provide opportunities to expose their undergraduate students to graduate-level research, while collaborations with Oak Ridge National Laboratory will significantly enhance the availability of research oportunities for both undergraduate and graduate students. ***