Chemical Engineering Commons^™

Synthesis And Energy Applications Of Oriented Metal Oxide Nanoporous Films, Qingliu Wu

University of Kentucky Doctoral Dissertations

This dissertation mainly addresses the synthesis of well-ordered mesoporous titania thin films by dip coating with PEO-PPO-PEO triblock copolymer surfactant template P123. Because P123 is composed of poly(ethylene oxide) [PEO] and poly(propylene oxide) [PPO] blocks, concentrations of ingredients are adjusted to tune the films’ wall thickness, pore size and mesophase. Structural changes are consistent with partitioning of species among PEO blocks, PPO blocks, and the PEO/PPO interface. Titanates localize near PEO and increase wall thickness (by 5 nm to 7 nm). Depending on aging temperature, PPG either swells the PPO cores (when it is hydrophobic) or introduces large (>200 …

Solution Phase And Membrane Immobilized Iron-Based Free Radical Reactions: Fundamentals And Applications For Water Treatment, Scott Romak Lewis

University of Kentucky Doctoral Dissertations

Membrane-based separation processes have been used extensively for drinking water purification, wastewater treatment, and numerous other applications. Reactive membranes synthesized through functionalization of the membrane pores offer enhanced reactivity due to increased surface area at the polymer-solution interface and low diffusion limitations. Oxidative techniques utilizing free radicals have proven effective for both the destruction of toxic organics and non-environmental applications. Most previous work focuses on reactions in the homogeneous phase; however, the immobilization of reactants in membrane pores offers several advantages. The use of polyanions immobilized in a membrane or chelates in solution prevents ferric hydroxide precipitation at near-neutral pH, …

Studies On Silicon Nmr Characterization And Kinetic Modeling Of The Structural Evolution Of Siloxane-Based Materials And Their Applications In Drug Delivery And Adsorption, Jyotrhirmai Ambati

University of Kentucky Doctoral Dissertations

This dissertation presents studies of the synthetic processes and applications of siloxane-based materials. Kinetic investigations of bridged organoalkoxysilanes that are precursors to organic-inorganic hybrid polysilsesquioxanes are a primary focus. Quick gelation despite extensive cyclization is found during the polymerization of bridged silane precursors except for silanes with certain short bridges. This work is an attempt to characterize and understand some of the distinct features of bridged silanes using experimental characterization, kinetic modeling and simulation. In addition to this, the dissertation shows how the properties of siloxane- materials can be engineered for drug delivery and adsorption.

The phase behavior of polymerizing …

Evaluation Of The Physicochemical Properties And Stability Of Solid Lipid Nanoparticles Designed For The Delivery Of Dexamethasone To Tumors, Melissa Howard

University of Kentucky Doctoral Dissertations

Pre-clinical and clinical trials suggest that pre-treatment with dexamethasone (Dex) may facilitate enhanced uptake of subsequently administered chemotherapeutic agents. To reduce the side effects associated with systemic administration of Dex, solid lipid nanoparticles (SLNs) containing dexamethasone palmitate (Dex-P) were prepared as a means of achieving tumor-targeted drug delivery. These studies were aimed at evaluating the physicochemical properties and both the physiological and storage stability of the SLNs.

SLNs were prepared using nanotemplate engineering technology. Stearyl alcohol (SA) was used as the lipid phase with Brij^® 78 and Polysorbate 60 as surfactants and PEG6000 monostearate as a long-chain PEGylating agent. …

Studies Related To Coulombic Fissions Of Charged Droplets And Hygroscopic Behavior Of Mixed Particles, Harry Cook Hunter Iii

University of Kentucky Doctoral Dissertations

This dissertation describes two independent studies related to charged aerosols. The first study examines the role of electrical conductivity on the amounts of charge and mass emitted during the break-up of charged droplets via Coulombic fission. The second study examines the hygroscopic behavior of mixed particles. The results from both studies are presented here in detail along with an in-depth discussion of pertinent literature and applications in modern technologies.

Charged droplets break-up via a process termed Coulombic fission when their charge density reaches a certain level during which they emit a portion of their charge and mass in the form …

Arsenite Oxidation By Pure Cultures Of Thiomonas Arsenivorans Strain B6 In Bioreactor Systems, Aniruddha Dastidar

University of Kentucky Doctoral Dissertations

The removal of arsenic toxicity from water is accomplished by a preliminary preoxidative step transforming the most toxic form, arsenite (As (III)), to the least toxic form, arsenate (As (V)). The potential of As (III) oxidation to As (V) was initially investigated in batch reactors using the chemoautotrophic Thiomonas arsenivorans strain b6 under varying initial As (III) and cell concentrations and at optimal pH and temperature conditions (pH 6.0 and temperature 30°C). The strain b6 completely oxidized As (III) to As (V) during exponential growth phase for lower levels of As (III) concentrations (≤ 100 mg/L) but continued into stationary …

Effect Of Fluorination On Partitioning Behavior And Bilayer Self Assembly, Vivian Aramide Ojogun

University of Kentucky Doctoral Dissertations

Fluorinated systems are defined by unique properties that offer advantages in drug delivery, material synthesis and industrial applications. In comparison to their hydrocarbon counterparts, the design of fluorinated solutes for tailored applications is limited by the inability to predict the effect of fluorination on phase behavior. This work examines and interprets the influence of fluorination on the phase behavior of fluorinated solutes and surfactants, with emphasis on their impact on vesicle bilayers.

Thermodynamic partitioning of functionalized series of fluorinated and hydrocarbon nicotinate prodrugs fashioned to promote solubility in a fluorocarbon solvent (perfluorooctyl bromide; PFOB) is measured. Predictive approaches are also …

Targeted Polymeric Biomaterials For The Prevention Of Post Surgical Adhesions, John M. Medley

University of Kentucky Doctoral Dissertations

Despite recent advances in surgical technique and the development of numerous therapeutic agents, the formation post surgical adhesions (PSA) continues to cause complications for many patients. In this research, we have employed a rational system to develop a novel treatment to address this clinical need. Based on an understanding of the biochemical events that lead to PSA formation, a series of targeted polymeric biomaterials was designed to interrupt the fibrin gel matrix propagation and suppress PSA formation.

Using group transfer polymerization, a series of well controlled block copolymers of polyacrylic acid and poly(ethylene glycol-methacrylate) based materials was synthesized. Subsequent functionalization …

Remote Controlled Hydrogel Nanocomposites: Synthesis, Characterization, And Applications, Nitin S. Satarkar

University of Kentucky Doctoral Dissertations

There is significant interest in the development of hydrogels and hydrogel nanocomposites for a variety of biomedical applications including drug delivery, sensors and actuators, and hyperthermia cancer treatment. The incorporation of nanoparticulates into a hydrogel matrix can result in unique material characteristics such as enhanced mechanical properties, swelling response, and capability of remote controlled (RC) actuation. In this dissertation, the development of hydrogel nanocomposites containing magnetic nanoparticles/carbon nanotubes, actuation with remote stimulus, and some of their applications are highlighted.

The primary hydrogel nanocomposite systems were synthesized by incorporation of magnetic nanoparticles into temperature responsive N-isopropylacrylamide (NIPAAm) matrices. Various nanocomposite properties …

Synthesis And Characterization Of Magnetic Hydrogel Nanocomposites For Cancer Therapy Applications, Samantha Ann Meenach

University of Kentucky Doctoral Dissertations

Currently, cancer is the second leading cause of death in the United States. Conventional cancer treatment includes chemotherapy, radiation, and surgical resection, but unfortunately, all of these methods have significant drawbacks. Hyperthermia, the heating of cancerous tissues to between 41 and 45°C, has been shown to improve the efficacy of cancer therapy when used in conjunction with irradiation and/or chemotherapy. In this work, a novel method for remotely administering heat is presented. This method involves heating of tumor tissue using hydrogel nanocomposites containing magnetic nanoparticles which can be remotely heated upon exposure to an external alternating magnetic field (AMF). The …

Nanoscale Functionalization And Characterization Of Surfaces With Hydrogel Patterns And Biomolecules, Hariharasudhan Chirra Dinakar

University of Kentucky Doctoral Dissertations

The advent of numerous tools, ease of techniques, and concepts related to nanotechnology, in combination with functionalization via simple chemistry has made gold important for various biomedical applications. In this dissertation, the development and characterization of planar gold surfaces with responsive hydrogel patterns for rapid point of care sensing and the functionalization of gold nanoparticles for drug delivery are highlighted.

Biomedical micro- and nanoscale devices that are spatially functionalized with intelligent hydrogels are typically fabricated using conventional UV-lithography. Herein, precise 3-D hydrogel patterns made up of temperature responsive crosslinked poly(N-isopropylacrylamide) over gold were synthesized. The XY control of the hydrogel …

Utilizing Mixed Surfactants For Simultaneous Pore Templating And Active Site Formation In Metal Oxides, Mohammed Shahidur Rahman

University of Kentucky Doctoral Dissertations

Self-assembled nonionic alkyl glycoside surfactants are of interest for creating functional adsorption and catalytic sites at the surface of mesoporous metal oxides, but they typically impart poor long-range order when used as pore templates. Improved order and control over the functional site density may be achieved by mixing them with a cationic surfactant. To confirm this hypothesis, we investigate the lyotropic liquid crystalline (LLC) phase behavior of aqueous solutions of the functional nonionic surfactant n-dodecyl β-D-maltoside (C₁₂G₂) and cationic cetyltrimethylammonium bromide (C₁₆TAB). A ternary phase diagram of the C₁₆TAB-C₁₂G_{2 …}

Multiscale Dynamic Monte Carlo / Continuum Modeling Of Drying And Curing In Sol-Gel Silica Films, Xin Li

University of Kentucky Doctoral Dissertations

Modeling the competition between drying and curing processes in polymerizing films is of great importance to many existing and developing materials synthesis processes. These processes involve multiple length and time scales ranging from molecular to macroscopic, and are challenging to fully model in situations where the polymerization is non-ideal, such as sol-gel silica thin film formation. A comprehensive model of sol-gel silica film formation should link macroscopic flow and drying (controlled by process parameters) to film microstructure (which dictates the properties of the films).

This dissertation describes a multiscale model in which dynamic Monte Carlo (DMC) polymerization simulations are coupled …

Surfactant And Metal Sorption Studies By Functionalized Membranes And Quartz Crystal Microbalance, Abhay R. Ladhe

University of Kentucky Doctoral Dissertations

Functionalized membranes provide an elegant platform for selective separations and sorptions. In this dissertation, application of functionalized membranes for surfactant and metal sorption studies are discussed. Sorption behavior of surfactants is also studied using quartz crystal microbalance (QCM) and other techniques.

Adsorption of the ethoxylated surfactants on polymeric materials (cotton and polyester) and model gold surface was quantified from a non-aqueous siloxane based solvent (D5) and water. The role of ethylene oxide group and the effect of nature of polymeric materials on adsorption behavior was quantified and established. In the case of gold-water interface, the adsorption data was fitted to …

Novel Catalysts For The Production Of Co- And Co2-Free Hydrogen And Carbon Nanotubes By Non-Oxidative Dehydrogenation Of Hydrocarbons, Wenqin Shen

University of Kentucky Doctoral Dissertations

Non-oxidative dehydrogenation of hydrocarbons is an attractive alternative route for the production of CO- and CO₂-free hydrogen. It will satisfy a major requirement for successful utilization of polymer electrolyte membrane (PEM) fuel cells (< 10 ppm CO) and sequestering carbon as a potentially valuable by-product, carbon nanotubes (CNTs). Due to the deposition of carbon on the surface of catalyst particles during the reaction, catalyst performance, life-time, and purification of the generated carbon product, are significant issues to solve in order to make the process practically feasible. The scope of this thesis includes: the development of novel Fe, Ni, and Fe-Ni catalysts supported on a Mg(Al)O support to achieve improved catalytic performance with easily-purified CNTs; evaluation of catalysts for ethane/methane dehydrogenation at moderate reaction temperatures; and study of activation and deactivation mechanisms by a variety of characterization techniques including TEM, HRTEM, XRD, Mössbauer spectroscopy, and x-ray absorption fine structure (XAFS) spectroscopy. The Mg(Al)O support was prepared by calcination of synthetic MgAl-hydrotalcite with a Mg to Al ratio of 5. The catalysts were prepared either by conventional incipient wetness method or by a novel nanoparticle impregnation method, where the monodisperse catalyst nanoparticles were prepared in advance by thermal decomposition of a metal-organic complex in an organic-phase solution and then dispersed onto the Mg(Al)O support. Dehydrogenation of undiluted methane was conducted in a fix-bed plug-flow reactor. Before reaction, the catalysts were activated by reduction in hydrogen. Fe-based catalysts exhibit a higher hydrogen yield at temperature above 600ºC compared with monometallic Ni catalyst. FeNi-9 nm/Mg(Al)O, Fe-10 nm/Mg(Al)O and Fe-5 nm/ Mg(Al)O nanoparticle catalysts show much improved performance and longer life-times compared with the corresponding FeNi IW/Mg(Al)O and Fe IW/Mg(Al)O catalysts prepared by incipient wetness. 10 nm is the optimum particle size for methane dehydrogenation. Addition of Ni to Fe forming a bimetallic FeNi alloy catalyst enhances the catalytic performance at the temperatures below 650ºC. Metallic Fe, Ni, FeNi alloy and Fe-Ni-C alloy, unstable iron carbide are all catalytically active components. Catalysts deactivation is due to the carbon encapsulation. The carbon products are in the form of stack-cone CNTs (SCNTs) and multi-walled CNTs (MWNTs), depending on the reaction temperature and catalyst composition. The growth of CNTs follows a tip growth mechanism and the purity of cleaned CNTs is more than 99.5%.

Texture, Microstructure And Formability Of Aluminum Alloys, Xiang-Ming Cheng

University of Kentucky Doctoral Dissertations

Texture, microstructure and formability were studied in Direct Chill Cast (DC) and Strip Cast (SC) aluminum alloys with regard to crystallographic anisotropy, the Portevin-Le Chatelier effect and aging softening behavior. It was found that material properties change greatly with manufacturing processes (DC vs. SC) and chemical composition (3xxx vs. 5 xxx alloys). DC cast hot band materials are usually fully recrystallized and have strong softening textures while SC hot band materials have a rolling structure with strong deformation textures. Softening textures cause 90 earing while deformation textures result in 45 earing after deep drawing. During cold rolling, 90 earing in …