Collaborative Research: Nano- and micro-particle transport prediction in subsurface media: The role of heterogeneity and structure

合作研究：地下介质中纳米和微米颗粒的输运预测：异质性和结构的作用

• 批准号: 1547495
• 负责人: Markus Hilpert
• 金额: $ 7.95万
• 依托单位: Johns Hopkins University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-03-15 至 2017-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1547495&HistoricalAwards=false
• 关键词: Collaborative; Research; Nano; micro; particle

Many water quality contexts exist in which particle transport and retention in saturated sands and gravels is a critical process; e.g., streambed removal of particle-bound contaminants, low energy drinking water treatment using riverbank filtration, engineered subsurface delivery of novel nanoparticles or bacteria for contaminant cleanup, and protection of drinking water supplies from disease-causing pathogen sources. There is yet insufficient capability to predict the observed complex transport behaviors of these particles under environmental conditions. Consequently, the theory to support optimized design of the above environmental systems is lacking. Mathematical models currently can describe but not predict these behaviors because, as yet, the models do not represent the underlying mechanisms and processes for particle attachment to surfaces under environmental conditions. The proposed research aims to determine whether observed complex colloid transport behaviors will emerge from pore-scale representation of the surface heterogeneity responsible for particle attachment. The proposed investigations involve parallel experiments and simulations at pore (micromodel) and network (packed sand column) scales. The research will provide for a transformative platform for researchers and practitioners to perform mechanistic prediction of particle transport for design of solutions to environmental problems. Additional broader impacts include engagement of middle and high school biology, chemistry, and earth science teachers in six-week long summer internships where they undertake field and laboratory experiences examining the role of particles in trace element transport and transformation.The capability to predict the observed complex transport behaviors of colloids under environmental conditions (e.g., non log-linear profiles of retained colloids, extended tailing of low concentrations, blocking, and ripening) is currently lacking. Empirically based continuum-scale rate constants and scaling factors are employed in the advection-dispersion equation to describe, and to a limited extent predict, the observed complex transport behaviors. Whereas these descriptions are extremely useful indicators of mechanisms, true predictive capability will be possible only if the underlying physicochemical mechanisms/processes are identified and parameterized at a more fundamental level. Pore scale (nanoscale) colloid-surface interactions are well-demonstrated to exert profound influences on colloid transport behaviors at the continuum scale (column and field). This research aims to determine whether the continuum-scale rate constants and scaling factors can be predicted, and the whether the observed complex continuum-scale behavior will emerge, from pore-scale representation of surface heterogeneity and network-scale representation of packing structure. This investigation involves parallel experiments and simulations at pore (micromodel) and continuum (column) scales. Coupled pore scale force/torque balance simulations will be conducted to pore/grain network simulations in order to develop mechanistic prediction of continuum scale rate constants and scaling factors. New approaches will be used to represent surface heterogeneity responsible for colloid attachment to bulk repulsive surfaces at the pore scale. The proposed research will also capitalize on, and extend, recent understanding of influences of topology at the continuum (network) scale where the transition between molecular (diffusion-driven) and particle (trajectory-driven) transport behaviors will be explored.

在许多水质环境中，饱和沙子和砾石中的颗粒迁移和保留是一个关键过程；例如，河床去除颗粒结合污染物、使用河岸过滤的低能耗饮用水处理、新型纳米粒子或细菌的工程地下输送以清除污染物，以及保护饮用水源免受致病病原体的影响。 目前还没有足够的能力来预测这些颗粒在环境条件下观察到的复杂传输行为。 因此，缺乏支持上述环境系统优化设计的理论。 目前的数学模型可以描述但不能预测这些行为，因为到目前为止，这些模型还不能代表环境条件下颗粒附着到表面的基本机制和过程。 拟议的研究旨在确定观察到的复杂胶体传输行为是否会从负责颗粒附着的表面异质性的孔隙尺度表示中出现。 拟议的研究涉及孔隙（微观模型）和网络（填充砂柱）尺度的并行实验和模拟。 该研究将为研究人员和从业者提供一个变革性平台，对颗粒输运进行机械预测，以设计环境问题的解决方案。 其他更广泛的影响包括初中和高中生物、化学和地球科学教师参与为期六周的暑期实习，他们在现场和实验室体验中检查粒子在微量元素传输和转化中的作用。目前，预测在环境条件下观察到的胶体复杂传输行为（例如，保留胶体的非线性分布、低浓度拖尾、阻塞和成熟）的能力正在开发中。 缺乏。 在平流色散方程中采用基于经验的连续尺度速率常数和比例因子来描述并在有限程度上预测观察到的复杂输运行为。 尽管这些描述是非常有用的机制指标，但只有在更基本的层面上识别和参数化潜在的物理化学机制/过程，才有可能实现真正的预测能力。 孔隙尺度（纳米尺度）胶体-表面相互作用已被充分证明对连续尺度（柱和场）的胶体输运行为产生深远影响。 本研究旨在确定是否可以从表面非均质性的孔隙尺度表示和堆积结构的网络尺度表示来预测连续尺度速率常数和比例因子，以及是否会出现观察到的复杂连续尺度行为。 这项研究涉及孔隙（微观模型）和连续体（柱）尺度的平行实验和模拟。 耦合孔隙尺度力/扭矩平衡模拟将应用于孔隙/颗粒网络模拟，以开发连续尺度速率常数和尺度因子的机械预测。 新方法将用于表示导致胶体在孔隙尺度上附着到本体排斥表面的表面异质性。 拟议的研究还将利用并扩展最近对连续体（网络）尺度上拓扑影响的理解，其中将探索分子（扩散驱动）和粒子（轨迹驱动）传输行为之间的转变。