CAREER: Interfacial Behavior of Microbubbles During Contaminant Stripping in Saturated Soils: Multiscale Investigations in Research and Education

9984206- BurnsThis教师早期职业发展（CAREER）研究和教育项目解决了管理离散气泡通过其他饱和土壤的形成和运动的物理因素。 在地质环境应用中，注入气泡的运输和分布对空气喷射过程的有效性至关重要-一种旨在将挥发性有机化合物移动到气相的原位汽提技术。 该项目包括一个实验，多尺度的调查，通过孔隙，孔隙网络和连续尺度土壤模型的空气气泡传输的动力学。空气传输的速率和模式被量化为注入压力/速度，注入孔，和界面张力在一个模型土壤孔隙的函数。 蚀刻玻璃micromodels被用来模拟空气通过土壤孔隙网络传输，和空气饱和度，气泡体积，和运输的异质性被量化为在孔隙尺度上确定的控制参数的函数。 微尺度调查操纵系统参数，如注射速度和界面张力，以确定导致气泡直径减小，气泡停留时间增加和气泡表面积增加的条件。 具有这些特征的汽提气泡显著增强了全球范围内的空气喷射过程。 将在孔隙和孔隙网络规模下获得的数据用作在连续体规模下进行的色谱柱检测的输入。 柱测试量化污染物去除效率，气泡聚结程度和传质效果，增强系统控制参数的基础上确定的孔隙和孔隙网络规模的调查，在这个多尺度调查中获得的数据将显着提高知识的状态，通过开发一个严格的，基本的了解变量，控制气泡运动，否则饱和土壤系统。 虽然提出的目标是在空气喷射的框架内设定的，但多尺度的基础研究结果同样适用于类似的过程，例如石油回收。与研究项目的发展平行，微尺度物理和化学现象的影响交织在本科土木工程课程，本科研究，以及一个旨在吸引中学女生学习科学和工程的讲习班。 考虑到多尺度的物理和化学行为被整合到课堂讲座和一系列的五分钟的课堂演示实验。 这些“变化”实验是精心设计的，以说明在工程实践中微观现象的宏观效应。 正在开发一个本科生补救案例研究课程，将微观物理和化学考虑纳入补救设计。 此外，正在制定和实施旨在鼓励中学女生学习科学和工程的推广讲习班。

9984206- BurnsThis Faculty Early Career Development (CAREER) research and education project addresses the physical factors that govern the formation and movement of discrete air bubbles through otherwise saturated soils. In geoenvironmental applications, the transport and distribution of injected air bubbles is critical to the effectiveness of the air sparging process -- an in-situ stripping technique designed to mobilize volatile organic compounds to the vapor phase. The project involves an experimental, multi-scale investigation into the dynamics of air bubble transport through pore, pore network, and continuum scale soil models.The rate and pattern of air transport is quantified as a function of injection pressure/velocity, injection orifice, and interfacial tension in a model soil pore. Etched glass micromodels are used to simulate air transport through soil pore networks, and the air saturation, bubble volume, and transport heterogeneity are quantified as a function of the controlling parameters identified at the pore scale. The microscale investigations manipulates the system parameters, such as injection velocity and interfacial tension, in order to identify the conditions that lead to decreased bubble diameter, increased bubble residence time, and increased bubble surface area. Stripping bubbles with these characteristics significantly enhances the air sparging process at the global scale. The data obtained at the pore and pore network scales is used as inputs for column tests performed at the continuum scale. The column tests quantifies contaminant removal efficiency, degree of bubble coalescence, and mass transfer effects, based on the enhanced system control parameters identified in the pore and pore network scale investigations.The data obtained in this multiscale investigation will significantly enhance the state of knowledge by developing a rigorous, fundamental understanding of the variables that control bubble movement through otherwise saturated soil systems. While the objectives proposed are set within the framework of air sparging, the results of the multiscale, fundamental investigation are equally applicable to similar processes, such as petroleum recovery.Parallel to the developments in the research project, the influence of microscale physical and chemical phenomena is interwoven into undergraduate Civil Engineering courses, undergraduate research, and a workshop targeted to attract middle school girls to pursue the study of science and engineering. Consideration of multiscale physical and chemical behavior is integrated into classroom lectures and a series of five-minute classroom demonstration experiments. These "change-up" experiments are carefully designed to illustrate the macroscale effects of microscale phenomena in engineering practice. An undergraduate remediation case studies course that incorporates microscale physical and chemical considerations into remedial design is being developed. Additionally, an outreach workshop designed to encourage middle school girls in the study of science and engineering is being developed and implemented.