Investigation of Mechanisms of Surfactant-Induced Hydraulic Conductivity Changes in Soil Flushing Operations

本研究的目的是了解在表面活性剂处理后土壤中产生水力导电性变化的基本机制，并建立一个数学模型，供科学家和工程师使用，以预测用特定表面活性剂和剂量处理特定土壤时水力导电性变化的幅度和方向。研究粘土含量和类型、表面活性剂类型和浓度以及土壤结构的作用，以提高对任何土壤-表面活性剂体系的基本认识和预测能力。两个非离子表面活性剂和一个阴离子表面活性剂将在三个阶段中的每一个阶段进行检查。前两个阶段将重点了解四种已确定的改变水力导电性的机制。第一阶段将研究对流体或土壤介质的直接物理影响和诱导的二次化学反应；第二阶段将研究土壤团聚体的破坏和细粒的产生，以及表面活性剂与粘土的相互作用。第三阶段旨在检查人工土壤中变量的组合，以了解各个机制之间的相互关系，并评估前两个阶段开发的预测能力。此外，第三阶段的一个主要目标将是开发一种能够描述实验工作观察结果的数学工具，从而开发预测能力。拟议的项目有可能对基础科学和土壤表面活性剂相互作用的理解以及将这些知识应用于现实世界的修复项目作出重大贡献。

The objective of this research is to learn the fundamental mechanisms that produce a change of hydraulic conductivity in soil when treated with surfactants and to develop a mathematical model that can be used by scientists and engineers to predict the magnitude and direction of hydraulic conductivity change upon treatment of a particular soil with a specific surfactant and dose. The roles of clay content and type, of surfactant type and concentration and of soil structure will be investigated in order to advance fundamental understanding and predictive capabilities applicable for any soil-surfactant system. Two nonionic and one anionic surfactants will be examined in each of three phases. The first two phases will focus on understanding the four identified mechanisms by which hydraulic conductivity is altered. The first phase will investigate direct physical effects on fluid or soil media and induced secondary chemical reactions; the second phase will investigate the destruction of soil aggregate and production of fines, and surfactant-clay interactions. The third phase is designed to examine combinations of variables in artificial soils to understand the interrelationships among the individual mechanisms and to assess the predictive abilities developed in the first two phases. In addition, a primary goal of the third phase will be the development of a mathematical tool capable of describing the observations of the experimental work, from which predictive capabilities will be developed. The proposed project has the potential of making significant contributions to the basic science and understanding of soil-surfactant interaction and to the application of that knowledge to real-world remediation projects.