Research Initiation Award: Novel Approaches to Probing the Mechanism of Brownian Colloid Release from Packed Bed Surfaces

研究启动奖：探索填充床表面布朗胶体释放机制的新方法

• 批准号: 9410301
• 负责人: Joseph Ryan
• 金额: $ 10万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-09-01 至 1998-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9410301&HistoricalAwards=false
• 关键词: Research; Initiation; Award; Novel; Approaches

ABSTRACT Joseph Ryan CTS-9410301 The transport of low-solubility contaminants like radionuclides, metals, and hydrophobic organic compounds is directly linked to the transport of colloids. The diffusion-driven release of Brownian colloids from porous media surfaces is influenced by the chemistry of the colloid and porous media surfaces, the solution chemistry (pH, ionic strength), the flow velocity, and the colloid and grain sizes. In the past, the kinetics of colloid release were modeled as a first-order exchange between attached and detached colloids in a manner analogous to Arrhenius kinetics. Under certain conditions, this approach has failed, owing to peculiarities in the calculation of the intersurface potential energy. Preliminary experimental results have indicated that colloid release is actually a two-step mechanism consisting of (1) detachment from the surface controlled by surface and solution chemistry and (2) diffusion across the boundary layer controlled by the effect of flow velocity diffusion coefficient. The experiments proposed here are designed to proof the two-step mechanism by attempting to isolate and quantify each step. The detachment step will be isolated by conducting experiments in non-moving fluid. The diffusion step will be isolated by removing the energy barrier. The results of the experiments will be analyzed to develop a quantitative kinetic model of colloid release. The project addresses environmental concerns in groundwaters.

摘要Joseph Ryan CTS-9410301 低溶解度污染物如放射性核素、金属和疏水性有机化合物的运输与胶体的运输直接相关。 布朗胶体从多孔介质表面的扩散驱动释放受到胶体和多孔介质表面的化学性质、溶液化学性质（pH、离子强度）、流速以及胶体和颗粒尺寸的影响。 在过去，胶体释放的动力学被建模为附着和脱离的胶体之间的一级交换，其方式类似于阿克里什动力学。 在某些条件下，这种方法失败了，由于在计算界面势能的特殊性。 初步实验结果表明，胶体释放实际上是一个两步机制，包括（1）由表面和溶液化学控制的从表面脱离和（2）由流速扩散系数的影响控制的穿过边界层的扩散。 这里提出的实验旨在通过尝试隔离和量化每个步骤来证明两步机制。 分离步骤将通过在非移动流体中进行实验来隔离。 扩散步骤将通过去除能量势垒而被隔离。 将对实验结果进行分析，以建立胶体释放的定量动力学模型。 该项目涉及地下水的环境问题。