Ethyl Cellulose Nanoparticles and Porous Media: Fundamentals and Applications

非水相液体在运输或工业活动过程中的排放是对地表和地下水生环境健康的严重关切。特别是从地下清除，这是一个令人头疼的问题，因为在确定污染源区域的特征和目标、监测修复性能以及就地运送对污染物具有选择性的修复试剂方面存在很大困难。工程纳米材料在提高现有和新的补救技术的有效性方面具有巨大潜力；然而，材料可持续性方面的挑战以及纳米颗粒在多孔介质中传输和分布的障碍阻碍了在广泛应用方面的进展。该研究计划的长期愿景是应对这些挑战，在未来五年战略性地将我们当前的努力集中在一种新兴的可持续纳米材料-乙基纤维素(EC)上，该材料来自大量可获得的纤维素。基于我们对表面力在EC纳米颗粒在气-液和液-液界面的附着和组装中所起作用的定量理解，我们将使用EC-NP悬浮液作为一个模型系统来研究NP与多孔介质中流动和静止的流体-流体界面的相互作用(即在孔网络和连续介质尺度上)。对在不同尺度上运行的物理过程的系统描述是拟议研究方案的一个显著特点。从EC-NPs研究中获得的基础知识将使不仅基于EC-NPs，而且基于从纤维素或木质素衍生的更复杂的可持续纳米材料的应用程序的合理开发成为可能。拟议的研究计划将在两个主要方向展开。第一部分将利用实验和模拟研究在单相流、两相流和三相流条件下，EC-NP在宿主多孔介质(土壤和岩石)中传输的基本方面。这一点很重要，因为NP在流体界面的附着影响并受到不混相驱替动力学的影响，这些动力学是地下修复应用的基础(例如，NP稳定的泡沫驱、NPs的污染物传感、疏水污染物的固定、原地污染物屏障)、石油开采和古迹保护。第二个方向将试验性地使用EC-NPs稳定的油水(O/W)乳液作为模板，以创建用于O/W分离的疏水/亲油多孔材料，并用作润湿性控制的涂层。最终，这项研究将导致可持续技术的开发和在胶体科学和多孔介质中的传输方面培训高素质的人员，这些领域正在显著增长，需要训练有素的人员，因为先进材料正开始部署在地质环境中。

The discharge of non-aqueous phase liquids in the course of transportation or industrial activity is a cause of grave concern for the health of both surface and subsurface aquatic environments. Their removal from the subsurface in particular, is a vexing problem, due to great difficulty with the characterization and targeting of source zones, the monitoring of remediation performance, and the in situ delivery of remediation agents with selectivity toward contaminants. Engineered nanomaterials have great potential to improve the efficacy of existing and novel remediation technologies; however, challenges with material sustainability and barriers to nanoparticle transport and distribution in porous media, have hampered progress towards widespread deployment. The long term vision of this research program is to address these challenges, strategically focusing our immediate efforts over the next five years on an emerging sustainable nanomaterial, ethyl cellulose (EC), derived from abundantly available cellulose. Capitalizing on our quantitative understanding of the role surface forces play in the attachment and assembly of EC nanoparticles (NPs) at gas--liquid and liquid--liquid interfaces, we will use EC- NP suspensions as a model system to investigate NP interactions with mobile and immobile fluid--fluid interfaces  in porous media (i.e., at the pore- network and continuum scales). The systematic characterization of physical processes operative at different scales is a distinguishing feature of the proposed research program. Fundamental knowledge gained from the study of EC-NPs will enable the rational development of applications based not only on EC-NPs, but on more complex sustainable nanomaterials derived from cellulose or lignin. The proposed research program will unfold in two main directions. The first will investigate, using experiments and simulations, fundamental aspects of EC-NP transport in host porous media (soil and rock), under conditions of single-, two- and three--phase flow. This is important because NP attachment at fluid interfaces affects and is affected by the dynamics of immiscible displacement - dynamics which underpin applications in subsurface remediation (e.g., NP--stabilized foam flooding, contaminant sensing by NPs, immobilization of hydrophobic contaminants, in situ contaminant barriers), oil recovery and monument preservation. The second direction will address experimentally the use of oil--water (O/W) emulsions stabilized by EC- NPs as templates for the creation of hydrophobic/oleophilic porous materials used for O/W separation and as coatings for wettability control. Ultimately, this research will lead to the development of sustainable technologies and the training of highly-qualified personnel at the interface of colloid science and transport in porous media, fields seeing significant growth and requiring highly trained personnel as advanced materials are beginning to be deployed in geologic settings.