Browsing by Subject "Separations"
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Item Functional polymers: polyoxanorbornene-based block copolymers for the separation of f-elements and luminescent conducting metallopolymers(2014-05) Mitchell, Lauren Avery; Holliday, Bradley J.; Jones, Richard A; Humphrey, Simon M; Ellison, Christopher J; Landsberger, SheldonA new polymeric material with a polyoxanorbornene backbone and carbamoylmethylphosphine oxide, CMPO, ligand pendant groups has been synthesized, characterized, and studied. The ability of the material to selectively partition actinides utilizing a biphasic extraction strategy was tested. The polymeric materials had significantly higher (> 5-25 times) ability to extract Th4+ than the monomeric system. The molecular weight of the material affected the extraction and separation abilities. The lower molecular weight material extracted more ions, but was less discriminate for thorium(IV) over cerium(III), lanthanum(III), and europium(III), than the higher molecular weight material. Structural modifications to this system were made by creating block copolymers. The influence of additional functionalities, created by the addition of new polymeric blocks, was investigated. The ability of the material to selectively partition actinides utilizing both solid-liquid and liquid-liquid extraction strategies was tested. Extraction efficiencies comparable to liquid-liquid extractions were achieved in the solid-liquid extractions. The extraction behavior of the materials was significantly altered by the incorporation of new blocks. The incorporation of glycol chains into the system caused an increase in the uptake of thorium(IV) over the homopolymers. The incorporation of blocks of glycol chains and blocks of cross-linked hydroxcoumarian increased the selectivity significantly (XTh/Eu 2.3 – 4.5 times higher) over the homopolymer. These materials show tremendous promise as modular polymeric scaffolds. A novel emissive tetradentate platinum complex with electropolymerizable ethylenedioxythiophene groups has been synthesized and characterized. This material has been developed for use as the active layer in polymer light-emitting diodes. Electropolymerization offers ease of processing by depositing thin films directly onto an electrode during the polymerization process. Additionally because the emitter is covalently bound in the polymer, it cannot aggregate as is the case with some small molecule emitters. The platinum complex displayed emission peaks at 510 nm and 544 nm. Electropolymerization resulted in a conductive and emissive thin film, with an emission maximum at 453 nm.Item Supported Lipid Bilayer Electrophoresis: A New Paradigm in Membrane Biophysics and Separations(2012-11-28) Pace, Hudson 1982-The motivation of this work was to produce novel analytical techniques capable of probing the physical properties of the cell surface. Many researchers have used supported lipid bilayers (SLBs) as models to study the structure and function of the cell membrane. The complexity of these models is consistently increasing in order to better understand the myriad of physiologically relevant processes regulated by this surface. In order to aid researchers in studying such phenomenon, the following contributions were made. To manipulate components within the cell membrane, an electrophoretic flow cell was designed which can be used as a probe to study the effect of electrical fields on charged membrane components and for the separation of these components. This devise allows for the strict control of pH and ionic strength as species are observed in real-time using fluorescence microscopy. Additionally, advancements have been made to the production of patterned heterogeneous SLBs for use in separations and to probe the interactions of membrane components. The methodology to couple SLB separations and matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) imaging was devised. This technology allows for the label-free mapping of the SLB surface post electrophoresis in order to observe naturally occurring species unperturbed by the addition of extrinsic tags. The final contribution, and perhaps the greatest, is the development of a procedure to create highly mobile SLBs from native membranes. These surfaces have vast potential in that they are no longer simple models of the cell surface, they are in fact the actual cell surface made planar. This advancement will be of great use to biophysicists and biochemists interested in using surface specific analytical methods to better understand physiological processes. These highly mobile native membrane surfaces have been coupled with the SLB electrophoresis technology to separate discrete bands of lipids and proteins, a proof of principle that will hopefully be further developed into a standard method for membrane proteomic studies. Collectively the tools and methodologies described herein show great potential in allowing researchers to further add to mankind?s understanding of the cellular membrane.Item Synthesis and design of optimal thermal membrane distillation networks(Texas A&M University, 2006-10-30) Nyapathi Seshu, MadhavThermal membrane distillation is one of the novel separation methods in the process industry. It involves the simultaneous heat and mass transfer through a hydrophobic semipermeable membrane through the use of thermal energy to bring about the separation of a feed mixture into two streams- a permeate and a retentate stream. Traditionally, studies on this technology have focused on the performance of individual modules as a function of material of the membrane and also configuration of the membrane. However, an investigation into the performance of a network of these modules has not been conducted in the past. A hierarchical parametric programming technique for synthesis of an optimal network of these modules is presented. A global mass allocation representation involving sources and sinks was used to solve the problem and derive criteria for optimality in specific regions of the parametric space. Two case studies have been presented to illustrate the applicability of the presented methodology.Item Thermodynamic and mass transfer modeling of aqueous hindered amines for carbon dIoxide capture(2016-05) Sherman, Brent Joseph; Rochelle, Gary T.; Baldea, Michael; Chen, Chau-Chyun; Chen, Eric; Hwang, GyeongWith the detrimental effects of global climate change beginning to be felt, there is a growing consensus that something must be done. One part of the solution is carbon capture and storage using amine scrubbing to capture 90% of the CO2 from power plants burning coal and natural gas. To actualize this solution, process models are necessary. A process model requires an accurate thermodynamic and mass transfer model with physically meaningful parameters. While hindered amines are commercially used, the reason for their mass transfer rates is still an open question. These two needs are addressed in this work. To improve thermodynamic modeling, the physical significance of the electrolyte non-random two-liquid (eNRTL) regressed binary interaction parameters were examined. To improve mass transfer modeling, a response surface methodology (RSM) approach was used to give statistically significant regressed parameters. The mass transfer of two hindered amines, 2-amino-2-methyl-propan-1-ol (AMP) and 2-piperidineethanol (2PE) was studied to determine the role of carbamate. The absolute difference in eNRTL binary interaction parameters was found to moderately correlate with the pKa of the amine. An analogy method was developed to enable thermodynamic model creation for amines in the absence of some physical property data. The carbamate reaction plays a determining role in mass transfer of hindered amines. Based on Bronsted plots, 2PE appears to form carbamate using the same mechanism as unhindered, cyclic secondary amines, while AMP does not seem to use the same mechanism as unhindered, primary amines. The rate constant for bicarbonate formation for both amines is a factor of twelve faster than predicted from tertiary amine bicarbonate formation, indicating that neither seems to form bicarbonate using the tertiary amine mechanism. The six models constructed in this work enable process modeling and economic comparisons of solvents. Four binary interaction parameters were the most physically significant and should be regressed for future solvents. The high bicarbonate reaction rate of the hindered amines should be further investigated to determine if the mechanism is different or if this is model artifice, as either outcome will substantially improve mass transfer modeling for all amines.