This dissertation presents the results of a series of experimental and numerical studies designed to advance knowledge of the fundamental mechanisms controlling colloidal particle transport in saturated porous media. That colloidal particles facilitate contaminant transport in porous media, or act as contaminant sources, is well known, and also widely recognized as important to environmental and health issues around the world. Many prior and ongoing studies are aimed at understanding particle transport and deposition behavior in saturated porous media, and these studies have generated a broad range of knowledge regarding particle fate and transport mechanisms. However, the prediction of particle transport behavior still remains challenging, not least because the particle transport processes themselves still include many unknown factors. The goal of the work reported in this dissertation, was to advance understanding of the influence of varying flow velocity conditions, flow direction, particle size and mixed particle populations on particle transport processes. In order to meet this goal, a new numerical model for particle transport was developed, and standard laboratory column test protocols were modified to enable the imposition of varying flow conditions during a test, as well as visualization of particle concentrations within the interior of a column. In addition, and in collaboration with other researchers, numerical modeling work was also undertaken to provide insight into the processes governing particle transport at an instrumented field site. Numerical models have been used extensively to investigate a wide variety of engineering and applied science problems, including those involving colloidal particle transport in saturated porous media. For the research presented in this dissertation, a new numerical model, termed the Kinetic Colloid Transport Model (KCTM), was developed and implemented using the Matlab platform. The KCTM is based on a one-dimensional (1-D) advection-dispersion-sorption equation coupled with different kinetic sub-models for simulating particle interactions with the solid phase of a porous medium, including irreversible and reversible attachment mechanisms, as well as two-attachment site and two-particle population behaviors. The KCTM is capable of directly simulating particle transport behavior for a given set of initial and boundary conditions, and also inversely solving for the sub-model kinetic parameters based on particle concentrations observed during column or field experiments. To validate the KCTM, KCTM results were compared with analytical solutions generated by the STANMOD program and numerical solutions generated by HYDRUS-1D. Simulation of particle breakthrough concentrations during a hypothetical column experiment with fourteen different case studies, involving a range of particle dispersion coefficients as well as attachment and detachment rates, was used for the validation. Agreement between the KCTM results and those generated by STANMOD and HYDRUS-1D, as defined by corresponding R squared values (all above 0.999), was considered acceptable across all ten case studies. The KCTM has the advantage of modeling a range of particle transport mechanisms, many of which are not accounted for in current open-source or commercially available codes. Fluctuating or varying velocity conditions are common under many real-world scenarios involving colloidal particle transport, yet are often neglected in laboratory column experiments designed to investigate particle transport behavior. To understand the influence of varying velocity conditions on particle transport, a series of traditional and modified laboratory column experiments was conducted. For the modified column experiments, a protocol was developed to enable the simulation of both increasing and decreasing velocity conditions during a test, as well as conditions involving an increase followed by a decrease in velocity. Laboratory column experiments were performed to examine the downward transport of 2 micron diameter microspheres through a saturated bed of 100 micron diameter glass beads under both constant and varying velocity conditions. The KCTM was simultaneously fit to observed particle concentration breakthrough curves, as well as measured particle concentrations retained in the column at the end of each constant velocity experiment, to obtain a relationship between a dimensionless irreversible kinetic attachment coefficient Ki* and transport velocity. This relationship was then used to model the results of the varying velocity tests, with limited success. A comparison of the Ki* values obtained from direct fitting of the varying velocity tests using the KCTM, with the Ki* values derived from the results of the constant velocity experiments, revealed a potential dependence of Ki* on the rate of change of transport velocity, which is currently not accounted for in any particle transport model. Overall, the results of this experimental and numerical investigation pointed to the need for better understanding of how varying velocity conditions impact fundamental particle transport mechanisms. A visualization technique was used to examine the effects of particle size and flow direction on particle transport in a saturated porous medium comprised of 500μm diameter glass beads. Packed column experiments with uniform (100% 1μm or 100% 6μm) and mixed (90% 1μm with 10% 6μm and 90% 6μm with 10% 1μm) polystyrene latex microspheres were performed in one-dimensional upward, horizontal and downward flow fields at a constant velocity of 1.7m/day. Particle concentrations were recorded over time in the interior of a column and at the column exit. Experimental results showed that upward flow conditions generally gave rise to higher retained particle concentrations and lower particle breakthrough concentrations than horizontal and downward flow conditions, indicating that gravitational settling decreases particle transport distances and enhances particle deposition mechanisms. Consistent with prior studies, results also showed increasing particle retention with increasing particle size. The 1μm particle tests results were successfully modeled using a first order, irreversible particle attachment model, indicating little filtration of this particle size within the glass bead columns during transport. Modeling of the 6μm particle tests required a two-site kinetic modeling approach that accounted for particle interactions with the surfaces of the glass beads as well as straining of particles at bead-bead contact points. The presence of a second particle population had little impact on the transport of the 1μm particles. For the 6μm particles, the presence of the second particle population increased particle attachment rates, with the greatest impact observed during downward flow conditions. Overall, the results of this study confirm that particle size and flow direction impact particle transport processes. The study also reveals that particle size heterogeneity could also impact particle transport under certain conditions. Both of these findings have implications for field-scale modeling of particle transport. The up-scaling of results obtained from laboratory column experiments to predict particle transport at the field scale is generally reported to under-estimate particle transport distances observed in the field. The over-simplification of column experimental conditions, in comparison to field conditions, or the use of improper kinetic models are two possible reasons leading to such inaccurate predictions. In order to explore the possible hurdles to current up-scaling methods, the KCTM was used to analyze a series of Escherichia coli based column experiments using aquifer sand obtained from a field site in Bangladesh, which are described in the collaborative work presented in Appendix A. Four E.coli breakthrough curves (BTCs) and two profiles of spatially retained E.coli concentrations at the end of an experiment were generated by the column test series. The KCTM successfully modeled the BTC results using a two-population kinetic sub-model. Both one-site and two-site particle attachment sub-models failed to reproduce the observed BTCs. None of the kinetic sub-models could reproduce the observed particle retention profiles, although the two-population sub-model generated similar hyper log-linear profiles to those seem in the experiment results. Low mass recovery rates in the column experiments is one possible reason why the KCTM failed to fit the retained profiles. The kinetic parameters obtained from the KCTM fits to the column experimental results were incorporated into a two-dimensional transport model, HYDRUS-2D, to predict E. coli transport observed at an instrumented field in Bangladesh. Predictions obtained using only irreversible attachments kinetics, reversible attachment kinetics and both reversible and irreversible attachment kinetics performed with RMSE values of 1158, 826, and 99, respectively. The dramatic decrease in RMSE with the application of the two-site kinetic model indicates that E. coli transport at the field site likely involves both reversible and irreversible attachment. An important conclusion of this work was the significance of designing laboratory column experiments that can enable the extraction of kinetic parameters relevant to field scale transport processes. The numerical and experimental studies presented in this dissertation examined some factors that influence particle fate and transport in saturated porous media, which are commonly overlooked in many conceptual and numerical models of particle behavior. The results of these studies point to a need to better understand how varying velocity conditions, flow direction, particle size and mixed particle populations influence particle fate and transport. The results of these studies also prompt out several recommended future works. For the developed numerical model, current kinetic sub-models imperfectly reproduced experiment results, also inadequately described the particle transport in microscale observations, indicating the simplified first-order kinetics are inaccurate for describing actual particle transport behaviors. A non-log-linear kinetic sub-model and corresponding micro-scale experiments are needed for better predictions. Moreover, the effects of particle-particle interaction were proven significant in certain conditions, however, the processes is still unclear. Visualization technique introduced in this research is capable to explore the controlling mechanisms in micro-scale and further provides the foundations for developing non-log-linear kinetic model, quantifying the effects of particle-particle interactions, acceleration, and other uncovered physical/chemical factors on particle transport in porous media. Advancing understanding of these factors has potential for improving the prediction of colloidal particle transport under real-world, field conditions, which can benefit many programs aimed at reducing the environmental and health impacts of colloid facilitated contaminant transport.

Mak Chung Ming = 多孔介質中的局部性與整體性漲落 / 麥仲明. / Thesis submitted in: July 2004. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 116-123). / Text in English; abstracts in English and Chinese. / Mak Chung Ming = Duo kong jie zhi zhong de ju bu xing yu zheng ti xing zhang luo / Mai Zhongming. / Abstract (in English) --- p.i / Abstract (in Chinese) --- p.ii / Acknowledgements --- p.iii / Table of Contents --- p.iv / List of Figures --- p.vi / List of Tables --- p.ix / Chapters / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Motivation of research on porous medium --- p.1 / Chapter 1.2 --- Description of porous medium --- p.2 / Chapter 1.3 --- Brief history of research of thermal convection in porous medium --- p.5 / Chapter 2. --- Background --- p.7 / Chapter 2.1 --- Introduction --- p.7 / Chapter 2.2 --- Governing equations and parameters --- p.8 / Chapter 2.3 --- Review of literature --- p.15 / Chapter 2.4 --- Summary --- p.20 / Chapter 3. --- Instrumentation --- p.21 / Chapter 3.1 --- Experimental setup --- p.21 / Chapter 3.1.1 --- Porous medium --- p.21 / Chapter 3.1.2 --- Working fluid --- p.24 / Chapter 3.1.3 --- Container cell --- p.25 / Chapter 3.1.4 --- Top plate --- p.26 / Chapter 3.1.5 --- Bottom plate --- p.28 / Chapter 3.2 --- Thermistors and its calibration --- p.28 / Chapter 3.3 --- Other apparatuses --- p.31 / Chapter 4. --- Data analysis and results --- p.33 / Chapter 4.1 --- Measurement of global heat flux --- p.33 / Chapter 4.1.1 --- Heat transfer characteristic --- p.34 / Chapter 4.2 --- Local temperature measurements --- p.37 / Chapter 4.2.1 --- 3mm bead´ؤwater system (small cell) --- p.38 / Chapter 4.2.2 --- 6mm bead´ؤwater system (small cell) --- p.44 / Chapter 4.2.3 --- 6mm bead´ؤwater system (large cell) --- p.64 / Chapter 4.2.4 --- 10mm bead´ؤwater system (large cell) --- p.76 / Chapter 4.3 --- Correlation of the time series --- p.96 / Chapter 4.4 --- Thermal pulse experiment --- p.101 / Chapter 5. --- Conclusions --- p.111 / Appendix --- p.114 / Bibliography --- p.116

Research in metal-organic frameworks (MOFs) has risen greatly in recent decades Owing to their unequaled potential tunability and structural diversity. MOFs may be described as crystalline structures composed of metal cations or clusters of cations, commonly referred to as secondary building units (SBUs), and custom-designed organic ligands. The variety of structural motifs, ligands, and SBUs that may be incorporated promote the attainment of essentially countless potential MOFs and application in numerous areas of interest, such as gas adsorption, catalysis, gas separation, and sensing. Further functionalization of MOF materials by means of post-synthetic modification(PSM)33–37 of metal clusters or organic ligands, constructing frameworks using functional ligands or metal clusters, and incorporating advantageous molecules including organometallic molecules,38–41 enzymes,42–45 metal nanoparticles (NPs),8,46–48 heteropolyacids49–51 within the pores advance the diverse number of species, including organic ligands, inorganic metal ions/clusters, and guests, used to construct MOFs materials lead to MOFs materials possessing phenomenal properties. Implementation of these materials in sensing arises from the frameworks’ characteristic ability to increase the concentration of a desired analyte to a greater degree than its overall presence within the system; imparting an inherent sensitivity to the aforementioned analyte. MOFs materials also possess the potential for selectivity for specific analytes or classes of analytes through mechanisms such as size exclusion (molecular sieving), chemically specific interactions between the adsorbate and framework, and the directed design of pore and aperture size through the selection of appropriate organic linkers or struts. Flexible azamacrocycle-based ligands are constructed through the use of pliable carboxylate pendant arms and azamacrocycles, e.g cyclen and tacn, and used in the pursuit of novel metal macrocycle frameworks (MMCF). Polyazamacrocycles represent a popular class of macrocyclic ligands for supramolecular chemistry and crystal engineering. This popularity may be due to their complexes’ high thermodynamic stability, relative kinetic inertness, basicity, transition metal-ion coordinating ability and rigid structure. Furthermore, their utilization promotes intriguing network topologies as coordination in complexes containing tetradentate azamacrocycles generally produces only two isomers differing via the coordination ligand’s conformation. The highly reported equatorial N4¬ ¬coordination of the macrocycle allows for interaction at the two vacant trans-axial positons, whilst the folded conformations permits interaction at two vacant cis positions. Azamacrocycle complexes differ from those of other classes of macrocycles due to the fact the macrocyclic cavity is commonly occupied by metal cations. Materials containing azamacrocycles have found use in applications such as bleaching and oxidative catalysis and molecular recognition. Cyclen units have reportedly been incorporated to construct pH-dependent selective receptors for copper (II), zinc(II), yttrium(III), and lanthanum(III) ions. Herein, we describe the synthesis and characterizations of a new lanthanide framework, La(C40H40N4O8)(NH2(CH2)2)NO3 or MMCF-3, which retains a vacancy in the macrocycle unit encourages the utilization of the framework as a cation receptor and precursor for heterometallic frameworks. The inclusion of azamacrocycles into MOF materials combine the characteristic high thermodynamic stability, basicity, and strong metal complexation of the macrocycles with the high porosity, surface area, and tunability of the frameworks. Full realization of the potential of Azamacrocyclic-based MOFs requires the preparation of new entrants to this class of materials that espouse various topological structures while incorporating diverse azamacrocycles. It has been shown that the hierarchical porosity associated with macrocyclic based frameworks can be obtained using this class of ligands.71,99 The development of more frameworks exhibiting this characteristic is needed to fully investigate the potential applications of MOFs retaining the vacant cavities of the azamacrocycles. Effectuation of hierarchical porosity of azamacrocyclic frameworks will broaden sensing applications, e.g. azamacrocycles have performed as receptors of anions, cations, amino acids and other analyte molecules, and provide an ideal slot to integrate open metal site into MOFs.

This work focuses on solute mass transport in a highly heterogeneous two-region porous medium consisting of spherical low-hydraulic conductivity inclusions, embedded in a high-hydraulic conductivity matrix. The transport processes occuring in the system are described by three distinct time scales. The first time scale reflects the characteristic time for convective transport in the high-conductivity matrix. The second time scale reflects the characteristic time for diffusive transport in the low-conductivity inclusions. The third time scale reflects the characteristic time for convection within the inclusions. Two Péclet numbers can be defined that compare the time scales and provide qualitative insight into the net transport behavior in two-region media. To model this system, four different representations were developed: (1) a Darcy-scale model that involved direct microscale computation over the entire domain of the experimental system, (2) a direct microscale simulation computed on a simplified domain that had similar geometric parameters (e.g. volume fraction of inclusions) as the complete domain for the experimental system, (3) a volume averaged model (after Chastanet and Wood [2008]) which uses a constant mass transfer coefficient and (4) a volume averaged model which employs a time-dependent mass transfer coefficient. Two different experimental conditions were investigated: a high flow rate, and a low flow rate. Detailed understanding of the experimental system was developed, which led to accurate prediction of the system's behavior for the higher flow rate. Accurate early time fit of the data was achieved for the experiment with the lower flow rate, while late time behavior between the models and experimental data diverged. Further investigations of the experimental system were conducted to examine possible sources of errors that could lead to an inaccurate description of the system's properties. Additional mixing within the system, inhomogeneous distribution of the effective diffusion coefficient and imprecise initial estimates of the hydraulic parameters are all possible explanations for the inaccurate model representation of the system's behavior for the lower flow rate case. / Graduation date: 2012

Thesis (Ph.D.)--University of Delaware, 2006. / Principal faculty advisor: Dionisios G. Vlachos, Dept. of Chemical Engineering. Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

Dissertation (Ph.D.)--Worcester Polytechnic Institute. / Keywords: Hydrogen; synthesis; Pd-Cu; metallic membranes; PD. Includes bibliographical references (leaves 331-346 ).

No description available.

The use of organic compounds as templates to assemble inorganic materials with structures over multiple length scales has received much attention due to the potential applications that can be developed from these materials. Many organisms synthesize organic/inorganic composites with exceptional control over morphology, physical properties, and nanoscale organization of these materials. Materials such as bone, nacre, and silica diatoms are excellent examples of the complex yet highly controllable hierarchically structured materials nature can form at ambient conditions. The ability to mimic these organisms through the design of supramolecular assemblies and use them to direct the growth of hierarchically structured materials has increased significantly in recent years. In this dissertation, block copolypeptide templated inorganic materials were synthesized and characterized using a wide range of analytical techniques. There are three major conclusions from this dissertation. First, the conformation of a polypeptide chain can be used to manipulate the porosity of oxide materials obtained. Second, individual supramolecular objects (vesicles) formed by block copolypeptides can be used as templates to form nanostructured hard materials. Third, polypeptide chemistry and solution conditions can be used to control both the morphology and porosity of the hard materials they assemble. This dissertation also describes preliminary work toward designing the block copolypeptides derivatives for biomimetic inorganic synthesis and gene delivery. This work includes the synthesis of these block copolypeptides derivatives and of the templated oxide materials. Some interesting silica materials such as porous silicas and silica nanocapsules were synthesized using double hydrophilic block copolypeptides derivatives as templates. Also, the preliminary work of using these block copolypeptides derivatives for gene delivery is included and shows these copolypeptide derivatives are potential delivery vehicles.

Thesis (Ph. D.)--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references.