On the Influence of Co-Constituents on Nanoparticle transport in Heterogeneous Porous Media

Nanotechnologies have been proposed for a variety of subsurface applications, including formation characterization, enhanced oil recovery, and in situ contaminant remediation. Upon introduction into the subsurface environment, nanoparticles will encounter a wide range of physical and chemical conditions, both natural and engineered, which may affect their mobility. Thus, an understanding of the influence of secondary constituents on nanoparticle transport behavior is an essential component in the development of mathematical models for nanoparticle mobility in the subsurface.;This dissertation presents an experimentally-validated mathematical framework that can simulate the influence of aqueous co-constituents, including brine and stabilizing copolymer molecules, on nanoparticle mobility in porous media for a variety of core, coating, and porous media types. In this framework, nanoparticle retention is described by a first-order attachment-detachment model, where kinetic attachment and detachment parameters are related to quantifiable physicochemical characteristics of the system. Here, the modeling framework is explored in the context of five examples: 1) an evaluation of the influence of residual poly (acrylic acid)-octylamine copolymer coating molecules on quantum dot nanoparticle transport; 2) a modeling investigation into the occurrence of hyper-exponential retention profiles in sand column experiments; 3) a description of nano-scale magnetite transport subject to transient brine chemistry; 4) validation of an experimentally parameterized mathematical model by predicting a larger-scale experimental result; 5) application of the developed modeling framework to a series of cross-well nanoparticle transport simulations in a field-scale domain.;The key outcome of this work is the development of a mathematical framework that successfully accounts for the influence of co-constituents on nanoparticle transport, and integrates those influences into a single mathematical simulator. The examples presented demonstrate the importance of accounting for the presence of secondary constituents at a variety of scales and show that the developed mathematical simulator is able to account for those influences on nanoparticle transport. Specifically, the developed mathematical simulator is successfully able to simulate the influence of secondary constituents on the blocking of nanoparticle deposition sites, transport and release behavior, transport in heterogeneous media, and account for all of these processes simultaneously. Future work should utilize the simulator developed here to further understand the effects of pH and subsurface uncertainty on nanoparticle transport in the environment.