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

Vanderbilt University, Nashville TN

Investigators

Abstract

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. ***