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- All Subjects: chemical engineering
- Genre: Doctoral Dissertation
- Creators: Lind, Mary Laura
Description
High temperature CO2 perm-selective membranes offer potential for uses in various processes for CO2 separation. Recently, efforts are reported on fabrication of dense ceramic-carbonate dual-phase membranes. The membranes provide selective permeation to CO2 and exhibit high permeation flux at high temperature. Research on transport mechanism demonstrates that gas transport for ceramic-carbonate dual-phase membrane is rate limited by ion transport in ceramic support. Reducing membrane thickness proves effective to improve permeation flux. This dissertation reports strategy to prepare thin ceramic-carbonate dual-phase membranes to increase CO2 permeance. The work also presents characteristics and gas permeation properties of the membranes. Thin ceramic-carbonate dual-phase membrane was constructed with an asymmetric porous support consisting of a thin small-pore ionic conducting ceramic top-layer and a large pore base support. The base support must be carbonate non-wettable to ensure formation of supported dense, thin membrane. Macroporous yttria-stabilized zirconia (YSZ) layer was prepared on large pore Bi1.5Y0.3Sm0.2O3-δ (BYS) base support using suspension coating method. Thin YSZ-carbonate dual-phase membrane (d-YSZ/BYS) was prepared via direct infiltrating Li/Na/K carbonate mixtures into top YSZ layers. The thin membrane of 10 μm thick offered a CO2 flux 5-10 times higher than the thick dual-phase membranes. Ce0.8Sm0.2O1.9 (SDC) exhibited highest CO2 flux and long-term stability and was chosen as ceramic support for membrane performance improvement. Porous SDC layers were co-pressed on base supports using SDC and BYS powder mixtures which provided better sintering comparability and carbonate non-wettability. Thin SDC-carbonate dual-phase membrane (d-SDC/SDC60BYS40) of 150 μm thick was synthesized on SDC60BYS40. CO2 permeation flux for d-SDC/SDC60BYS40 exhibited increasing dependence on temperature and partial pressure gradient. The flux was higher than other SDC-based dual-phase membranes. Reducing membrane thickness proves effective to increase CO2 permeation flux for the dual-phase membrane.
ContributorsLu, Bo (Author) / Lin, Yuesheng (Thesis advisor) / Crozier, Peter (Committee member) / Herrmann, Macus (Committee member) / Forzani, Erica (Committee member) / Lind, Mary Laura (Committee member) / Arizona State University (Publisher)
Created2014
Description
This dissertation presents a systematic study of the sorption mechanisms of hydrophobic silica aerogel (Cabot Nanogel®) granules for oil and volatile organic compounds (VOCs) in different phases. The performance of Nanogel for removing oil from laboratory synthetic oil-in-water emulsions and real oily wastewater, and VOCs from their aqueous solution, in both packed bed (PB) and inverse fluidized bed (IFB) modes was also investigated. The sorption mechanisms of VOCs in the vapor, pure liquid, and aqueous solution phases, free oil, emulsified oil, and oil from real wastewater on Nanogel were systematically studied via batch kinetics and equilibrium experiments. The VOC results show that the adsorption of vapor is very slow due to the extremely low thermal conductivity of Nanogel. The faster adsorption rates in the liquid and solution phases are controlled by the mass transport, either by capillary flow or by vapor diffusion/adsorption. The oil results show that Nanogel has a very high capacity for adsorption of pure oils. However, the rate for adsorption of oil from an oil-water emulsion on the Nanogel is 5-10 times slower than that for adsorption of pure oils or organics from their aqueous solutions. For an oil-water emulsion, the oil adsorption capacity decreases with an increasing proportion of the surfactant added. An even lower sorption capacity and a slower sorption rate were observed for a real oily wastewater sample due to the high stability and very small droplet size of the wastewater. The performance of Nanogel granules for removing emulsified oil, oil from real oily wastewater, and toluene at low concentrations in both PB and IFB modes was systematically investigated. The hydrodynamics characteristics of the Nanogel granules in an IFB were studied by measuring the pressure drop and bed expansion with superficial water velocity. The density of the Nanogel granules was calculated from the plateau pressure drop of the IFB. The oil/toluene removal efficiency and the capacity of the Nanogel granules in the PB or IFB were also measured experimentally and predicted by two models based on equilibrium and kinetic batch measurements of the Nanogel granules.
ContributorsWang, Ding (Author) / Lin, Jerry Y.S. (Thesis advisor) / Pfeffer, Robert (Thesis advisor) / Westerhoff, Paul (Committee member) / Nielsen, David (Committee member) / Lind, Mary Laura (Committee member) / Arizona State University (Publisher)
Created2011
Description
Environmentally responsive microgels have drawn significant attention due to their intrinsic ability to change volume in response to various external stimuli such as pH, temperature, osmotic pressure, or electric and magnetic fields. The extent of particle swelling is controlled by the nature of the polymer-solvent interaction. This thesis focuses on design and synthesis of environmentally responsive microgels and their composites, and encompasses methods of utilizing microgel systems in applications as vehicles for the adsorption, retention, and targeted delivery of chemical species. Furthermore, self-assembled microgel particles at ionic liquid (IL)-water interfaces demonstrate responsive colloidal lattice morphology. The thesis first reports on the fundamental aspects of synthesis, functionalization, and characteristic properties of multifunctional environmentally responsive microgels derived from poly(N-isopropylacrylamide) (PNIPAm) and other functional co-monomers. In particular, the uptake and release of active chemical species such as rheology modifiers into and from these ionic microgels is demonstrated. Moreover, a facile tunable method for the formation of organic-inorganic composites with Fe3O4 nanoparticles adsorbed and embedded within ionic microgel particles is explored. Additionally, the development of zwitterionic microgels (ZI-MG) is presented. These aqueous ZI-MG dispersions exhibit reversible parabolic swelling as a function of pH and display a minimum hydrodynamic diameter at a tunable isoelectric point (IEP). This study also elucidates the controlled uptake and release of surfactants from these particle systems. The extent of surfactant loading and the ensuing relative swelling/deswelling behaviors within the polymer networks are explained in terms of their binding interactions. The latter part of this thesis highlights the versatility of fluorescently labeled microgel particles as stabilizers for IL-water droplets. When the prepared particles form monolayers and equilibrate at the liquid-liquid interface, the colloidal lattice organization may re-order itself depending on the surface charge of these particles. Finally, it is shown that the spontaneously formed and densely packed layers of microgel particles can be employed for extraction applications, as the interface remains permeable to small active species.
ContributorsChen, Haobo (Author) / Dai, Lenore L (Committee member) / Chen, Kangping (Committee member) / Forzani, Erica (Committee member) / Lind, Mary Laura (Committee member) / Mu, Bin (Committee member) / Arizona State University (Publisher)
Created2015
Description
Membrane technology is a viable option to debottleneck distillation processes and minimize the energy burden associated with light hydrocarbon mixture separations. Zeolitic imidazolate frameworks (ZIFs) are a new class of microporous metal-organic frameworks with highly tailorable zeolitic pores and unprecedented separation characteristics. ZIF-8 membranes demonstrate superior separation performance for propylene/propane (C3) and hydrogen/hydrocarbon mixtures at room temperature. However, to date, little is known about the static thermal stability and ethylene/ethane (C2) separation characteristics of ZIF-8. This dissertation presents a set of fundamental studies to investigate the thermal stability, transport and modification of ZIF-8 membranes for light hydrocarbon separations.
Static TGA decomposition kinetics studies show that ZIF-8 nanocrystals maintain their crystallinity up to 200○C in inert, oxidizing and reducing atmospheres. At temperatures of 250○C and higher, the findings herein support the postulation that ZIF-8 nanocrystals undergo temperature induced decomposition via thermolytic bond cleaving reactions to form an imidazole-Zn-azirine structure. The crystallinity/bond integrity of ZIF-8 membrane thin films is maintained at temperatures below 150○C.
Ethane and ethylene transport was studied in single and binary gas mixtures. Thermodynamic parameters derived from membrane permeation and crystal adsorption experiments show that the C2 transport mechanism is controlled by adsorption rather than diffusion. Low activation energy of diffusion values for both C2 molecules and limited energetic/entropic diffusive selectivity are observed for C2 molecules despite being larger than the nominal ZIF-8 pore aperture and is due to pore flexibility.
Finally, ZIF-8 membranes were modified with 5,6 dimethylbenzimidazole through solvent assisted membrane surface ligand exchange to narrow the pore aperture for enhanced molecular sieving. Results show that relatively fast exchange kinetics occur at the mainly at the outer ZIF-8 membrane surface between 0-30 minutes of exchange. Short-time exchange enables C3 selectivity increases with minimal olefin permeance losses. As the reaction proceeds, the ligand exchange rate slows as the 5,6 DMBIm linker proceeds into the ZIF-8 inner surface, exchanges with the original linker and first disrupts the original framework’s crystallinity, then increases order as the reaction proceeds. The ligand exchange rate increases with temperature and the H2/C2 separation factor increases with increases in ligand exchange time and temperature.
Static TGA decomposition kinetics studies show that ZIF-8 nanocrystals maintain their crystallinity up to 200○C in inert, oxidizing and reducing atmospheres. At temperatures of 250○C and higher, the findings herein support the postulation that ZIF-8 nanocrystals undergo temperature induced decomposition via thermolytic bond cleaving reactions to form an imidazole-Zn-azirine structure. The crystallinity/bond integrity of ZIF-8 membrane thin films is maintained at temperatures below 150○C.
Ethane and ethylene transport was studied in single and binary gas mixtures. Thermodynamic parameters derived from membrane permeation and crystal adsorption experiments show that the C2 transport mechanism is controlled by adsorption rather than diffusion. Low activation energy of diffusion values for both C2 molecules and limited energetic/entropic diffusive selectivity are observed for C2 molecules despite being larger than the nominal ZIF-8 pore aperture and is due to pore flexibility.
Finally, ZIF-8 membranes were modified with 5,6 dimethylbenzimidazole through solvent assisted membrane surface ligand exchange to narrow the pore aperture for enhanced molecular sieving. Results show that relatively fast exchange kinetics occur at the mainly at the outer ZIF-8 membrane surface between 0-30 minutes of exchange. Short-time exchange enables C3 selectivity increases with minimal olefin permeance losses. As the reaction proceeds, the ligand exchange rate slows as the 5,6 DMBIm linker proceeds into the ZIF-8 inner surface, exchanges with the original linker and first disrupts the original framework’s crystallinity, then increases order as the reaction proceeds. The ligand exchange rate increases with temperature and the H2/C2 separation factor increases with increases in ligand exchange time and temperature.
ContributorsJames, Joshua B. (Author) / Lin, Jerry Y.S. (Thesis advisor) / Emady, Heather (Committee member) / Lind, Mary Laura (Committee member) / Mu, Bin (Committee member) / Seo, Dong (Committee member) / Arizona State University (Publisher)
Created2017
Description
Nanomaterials (NMs), implemented into a plethora of consumer products, are a potential new class of pollutants with unknown hazards to the environment. Exposure assessment is necessary for hazard assessment, life cycle analysis, and environmental monitoring. Current nanomaterial detection techniques on complex matrices are expensive and time intensive, requiring weeks of sample preparation and detection by specialized equipment, limiting the feasibility of large-scale monitoring of NMs. A need exists to develop a rapid pre-screening technique to detect, within minutes, nanomaterials in complex matrices. The goal of this dissertation is to develop a tiered process to detect and characterize nanomaterials in consumer products and environmental samples. The approach is accomplished through a two tier rapid screening process to screen likely presence/absence of elements present in common nanomaterials at environmentally relevant concentrations followed by a more intensive three tier characterization process, if nanomaterials are likely to occur. The focus is on SiO2 and TiO2 nanomaterials with additional work performed on hydroxyapatite (Ca5(PO4)3(OH)). The five step tiered process is as follows: 1) screen for elements in the sample by laser induced breakdown spectroscopy (LIBS) and X-ray fluorescence (XRF), 2) extract nanomaterials from the sample and screen for extracted elements by LIBS and XRF, 3) confirm presence and elemental composition of nanomaterials by transmission electron microscopy paired with energy dispersive X-ray spectroscopy, 4) quantify the elemental composition of the sample by inductively coupled plasma – mass spectrometry, and 5) identify mineral phase of crystalline material by X-ray diffraction. This dissertation found LIBS to be an accurate method to detect Si and Ti in food matrices (tier one approach) with strong agreement with the product label, detecting Si and Ti in 93% and 89% of the samples labeled as containing each material, respectively. In addition XRF identified Ti, Si, and Ca in 100% of food samples TEM-confirmed to contain Ti, Si, and Ca respectively. As a tier two approach, LIBS on the 0.2 micrometer filter identified nano silicon in 42% of samples confirmed by TEM to contain nano Si and 67% of TEM-confirmed samples to contain Ti. XRF identified Si, Ti, and Ca loaded on to a 0.1 µm filter and Ti in the surfactant rich phase of CPE of water and water with NOM.
ContributorsSchoepf, Jared (Author) / Westerhoff, Paul (Thesis advisor) / Dai, Lenore (Committee member) / Hristovski, Kiril (Committee member) / Herckes, Pierre (Committee member) / Lind, Mary Laura (Committee member) / Arizona State University (Publisher)
Created2018
Description
This dissertation focuses on the biosynthetic production of aromatic fine chemicals in engineered Escherichia coli from renewable resources. The discussed metabolic pathways take advantage of key metabolites in the shikimic acid pathway, which is responsible for the production of the aromatic amino acids phenylalanine, tyrosine, and tryptophan. For the first time, the renewable production of benzaldehyde and benzyl alcohol has been achieved in recombinant E. coli with a maximum titer of 114 mg/L of benzyl alcohol. Further strain development to knockout endogenous alcohol dehydrogenase has reduced the in vivo degradation of benzaldehyde by 9-fold, representing an improved host for the future production of benzaldehyde as a sole product. In addition, a novel alternative pathway for the production of protocatechuate (PCA) and catechol from the endogenous metabolite chorismate is demonstrated. Titers for PCA and catechol were achieved at 454 mg/L and 630 mg/L, respectively. To explore potential routes for improved aromatic product yields, an in silico model using elementary mode analysis was developed. From the model, stoichiometric optimums maximizing both product-to-substrate and biomass-to-substrate yields were discovered in a co-fed model using glycerol and D-xylose as the carbon substrates for the biosynthetic production of catechol. Overall, the work presented in this dissertation highlights contributions to the field of metabolic engineering through novel pathway design for the biosynthesis of industrially relevant aromatic fine chemicals and the use of in silico modelling to identify novel approaches to increasing aromatic product yields.
ContributorsPugh, Shawn (Author) / Nielsen, David (Thesis advisor) / Dai, Lenore (Committee member) / Torres, Cesar (Committee member) / Lind, Mary Laura (Committee member) / Wang, Xuan (Committee member) / Arizona State University (Publisher)
Created2016
Description
Environmentally responsive hydrogels are one interesting class of soft materials. Due to their remarkable responsiveness to stimuli such as temperature, pH, or light, they have attracted widespread attention in many fields. However, certain functionality of these materials alone is often limited in comparison to other materials such as silicon; thus, there is a need to integrate soft and hard materials for the advancement of environmental-ly responsive materials.
Conventional hydrogels lack good mechanical properties and have inherently slow response time, important characteristics which must be improved before the hydrogels can be integrated with silicon. In the present dissertation work, both these important attrib-utes of a temperature responsive hydrogel, poly(N-isopropylacrylamide) (PNIPAAm), were improved by adopting a low temperature polymerization process and adding a sili-cate compound, tetramethyl orthosilicate. Furthermore, the transition temperature was modulated by adjusting the media quality in which the hydrogels were equilibrated, e.g. by adding a co-solvent (methanol) or an anionic surfactant (sodium dodecyl sulfate). In-terestingly, the results revealed that, based on the hydrogels’ porosity, there were appre-ciable differences when the PNIPAAm hydrogels interacted with the media molecules.
Next, an adhesion mechanism was developed in order to transfer silicon thin film onto the hydrogel surface. This integration provided a means of mechanical buckling of the thin silicon film due to changes in environmental stimuli (e.g., temperature, pH). We also investigated how novel transfer printing techniques could be used to generate pat-terned deformation of silicon thin film when integrated on a planar hydrogel substrate. Furthermore, we explore multilayer hybrid hydrogel structures formed by the integration of different types of hydrogels that have tunable curvatures under the influence of differ-ent stimuli. Silicon thin film integration on such tunable curvature substrates reveal char-acteristic reversible buckling of the thin film in the presence of multiple stimuli.
Finally, different approaches of incorporating visible light response in PNIPAAm are discussed. Specifically, a chemical chromophore- spirobenzopyran was synthesized and integrated through chemical cross-linking into the PNIPAAm hydrogels. Further, methods of improving the light response and mechanical properties were also demonstrat-ed. Interestingly, such a system was shown to have potential application as light modulated topography altering system
Conventional hydrogels lack good mechanical properties and have inherently slow response time, important characteristics which must be improved before the hydrogels can be integrated with silicon. In the present dissertation work, both these important attrib-utes of a temperature responsive hydrogel, poly(N-isopropylacrylamide) (PNIPAAm), were improved by adopting a low temperature polymerization process and adding a sili-cate compound, tetramethyl orthosilicate. Furthermore, the transition temperature was modulated by adjusting the media quality in which the hydrogels were equilibrated, e.g. by adding a co-solvent (methanol) or an anionic surfactant (sodium dodecyl sulfate). In-terestingly, the results revealed that, based on the hydrogels’ porosity, there were appre-ciable differences when the PNIPAAm hydrogels interacted with the media molecules.
Next, an adhesion mechanism was developed in order to transfer silicon thin film onto the hydrogel surface. This integration provided a means of mechanical buckling of the thin silicon film due to changes in environmental stimuli (e.g., temperature, pH). We also investigated how novel transfer printing techniques could be used to generate pat-terned deformation of silicon thin film when integrated on a planar hydrogel substrate. Furthermore, we explore multilayer hybrid hydrogel structures formed by the integration of different types of hydrogels that have tunable curvatures under the influence of differ-ent stimuli. Silicon thin film integration on such tunable curvature substrates reveal char-acteristic reversible buckling of the thin film in the presence of multiple stimuli.
Finally, different approaches of incorporating visible light response in PNIPAAm are discussed. Specifically, a chemical chromophore- spirobenzopyran was synthesized and integrated through chemical cross-linking into the PNIPAAm hydrogels. Further, methods of improving the light response and mechanical properties were also demonstrat-ed. Interestingly, such a system was shown to have potential application as light modulated topography altering system
ContributorsChatterjee, Prithwish (Author) / Dai, Lenore L. (Thesis advisor) / Jiang, Hanqing (Thesis advisor) / Lind, Mary Laura (Committee member) / Yu, Hongyu (Committee member) / Yu, Hongbin (Committee member) / Arizona State University (Publisher)
Created2015
Description
In the United States, 95% of the industrially produced hydrogen is from natural gas reforming. Membrane-based techniques offer great potential for energy efficient hydrogen separations. Pd77Ag23 is the bench-mark metallic membrane material for hydrogen separation at high temperatures. However, the high cost of palladium limits widespread application. Amorphous metals with lower cost elements are one alternative to replace palladium-based membranes. The overall aim of this thesis is to investigate the potential of binary and ternary amorphous metallic membranes for hydrogen separation. First, as a benchmark, the influence of surface state of Pd77Ag23 crystalline metallic membranes on the hydrogen permeability was investigated. Second, the hydrogen permeability, thermal stability and mechanical properties of Cu-Zr and Ni60Nb35M5 (M=Sn, Ti and Zr) amorphous metallic membranes was evaluated.
Different heat treatments were applied to commercial Pd77Ag23 membranes to promote surface segregation. X-ray photoelectron spectroscopy (XPS) analysis indicates that the membrane surface composition changed after heat treatment. The surface area of all membranes increased after heat treatment. The higher the surface Pd/(Pd+Ag) ratio, the higher the hydrogen permeability. Surface carbon removal and surface area increase cannot explain the observed permeability differences.
Previous computational modeling predicted that Cu54Zr46 would have high hydrogen permeability. Amorphous metallic Cu-Zr (Zr=37, 54, 60 at. %) membranes were synthesized and investigated. The surface oxides may result in the lower experimental hydrogen permeability lower than that predicted by the simulations. The permeability decrease indicates that the Cu-Zr alloys crystallized in less than two hours during the test (performed at 300 °C) at temperatures below the glass transition temperature. This original experimental results show that thermal stability of amorphous metallic membranes is critical for hydrogen separation applications.
The hydrogen permeability of Ni60Nb35M5 (M=Sn, Ti and Zr) amorphous metallic membranes was investigated. Nanoindentation shows that the Young’s modulus and hardness increased after hydrogen permeability test. The structure is maintained amorphous after 24 hours of hydrogen permeability testing at 400°C. The maximum hydrogen permeability of three alloys is 10-10 mol m-1 s-1 Pa-0.5. Though these alloys exhibited a slight hydrogen permeability decreased during the test, the amorphous metallic membranes were thermally stable and did not crystalize.
Different heat treatments were applied to commercial Pd77Ag23 membranes to promote surface segregation. X-ray photoelectron spectroscopy (XPS) analysis indicates that the membrane surface composition changed after heat treatment. The surface area of all membranes increased after heat treatment. The higher the surface Pd/(Pd+Ag) ratio, the higher the hydrogen permeability. Surface carbon removal and surface area increase cannot explain the observed permeability differences.
Previous computational modeling predicted that Cu54Zr46 would have high hydrogen permeability. Amorphous metallic Cu-Zr (Zr=37, 54, 60 at. %) membranes were synthesized and investigated. The surface oxides may result in the lower experimental hydrogen permeability lower than that predicted by the simulations. The permeability decrease indicates that the Cu-Zr alloys crystallized in less than two hours during the test (performed at 300 °C) at temperatures below the glass transition temperature. This original experimental results show that thermal stability of amorphous metallic membranes is critical for hydrogen separation applications.
The hydrogen permeability of Ni60Nb35M5 (M=Sn, Ti and Zr) amorphous metallic membranes was investigated. Nanoindentation shows that the Young’s modulus and hardness increased after hydrogen permeability test. The structure is maintained amorphous after 24 hours of hydrogen permeability testing at 400°C. The maximum hydrogen permeability of three alloys is 10-10 mol m-1 s-1 Pa-0.5. Though these alloys exhibited a slight hydrogen permeability decreased during the test, the amorphous metallic membranes were thermally stable and did not crystalize.
ContributorsLai, Tianmiao (Author) / Lind, Mary Laura (Thesis advisor) / Lin, Jerry (Committee member) / Li, Jian (Committee member) / Arizona State University (Publisher)
Created2015
Description
Water recovery from impaired sources, such as reclaimed wastewater, brackish groundwater, and ocean water, is imperative as freshwater resources are under great pressure. Complete reuse of urine wastewater is also necessary to sustain life on space exploration missions of greater than one year’s duration. Currently, the Water Recovery System (WRS) used on the National Aeronautics and Space Administration (NASA) shuttles recovers only 70% of generated wastewater.1 Current osmotic processes show high capability to increase water recovery from wastewater. However, commercial reverse osmosis (RO) membranes rapidly degrade when exposed to pretreated urine-containing wastewater. Also, non-ionic small molecules substances (i.e., urea) are very poorly rejected by commercial RO membranes.
In this study, an innovative composite membrane that integrates water-selective molecular sieve particles into a liquid-barrier chemically resistant polymer film is synthetized. This plan manipulates distinctive aspects of the two materials used to create the membranes: (1) the innate permeation and selectivity of the molecular sieves, and (2) the decay-resistant, versatile, and mechanical strength of the liquid-barrier polymer support matrix.
To synthesize the membrane, Linde Type A (LTA) zeolite particles are anchored to the porous substrate, producing a single layer of zeolite particles capable of transporting water through the membrane. Thereafter, coating the chemically resistant latex polymer filled the space between zeolites. Finally, excess polymer was etched from the surface to expose the zeolites to the feed solution. The completed membranes were tested in reverse osmosis mode with deionized water, sodium chloride, and rhodamine solutions to determine the suitability for water recovery.
The main distinguishing characteristics of the new membrane design compared with current composite membrane include: (1) the use of an impermeable polymer broadens the range of chemical resistant polymers that can be used as the polymer matrix; (2) the use of zeolite particles with specific pore size insures the high rejection of the neutral molecules since water is transported through the zeolite rather than the polymer; (3) the use of latex dispersions, environmentally friendly water based-solutions, as the polymer matrix shares the qualities of low volatile organic compound, low cost, and non- toxicity.
In this study, an innovative composite membrane that integrates water-selective molecular sieve particles into a liquid-barrier chemically resistant polymer film is synthetized. This plan manipulates distinctive aspects of the two materials used to create the membranes: (1) the innate permeation and selectivity of the molecular sieves, and (2) the decay-resistant, versatile, and mechanical strength of the liquid-barrier polymer support matrix.
To synthesize the membrane, Linde Type A (LTA) zeolite particles are anchored to the porous substrate, producing a single layer of zeolite particles capable of transporting water through the membrane. Thereafter, coating the chemically resistant latex polymer filled the space between zeolites. Finally, excess polymer was etched from the surface to expose the zeolites to the feed solution. The completed membranes were tested in reverse osmosis mode with deionized water, sodium chloride, and rhodamine solutions to determine the suitability for water recovery.
The main distinguishing characteristics of the new membrane design compared with current composite membrane include: (1) the use of an impermeable polymer broadens the range of chemical resistant polymers that can be used as the polymer matrix; (2) the use of zeolite particles with specific pore size insures the high rejection of the neutral molecules since water is transported through the zeolite rather than the polymer; (3) the use of latex dispersions, environmentally friendly water based-solutions, as the polymer matrix shares the qualities of low volatile organic compound, low cost, and non- toxicity.
ContributorsKhosravi, Afsaneh Khosravi (Author) / Lind, Mary Laura (Thesis advisor) / Dai, Lenore (Committee member) / Green, Matthew (Committee member) / Lin, Jerry (Committee member) / Seo, Don (Committee member) / Arizona State University (Publisher)
Created2016
Description
Ionic liquids (ILs), or low-temperature liquid salts, are a class of materials with unique and useful properties. Made up entirely of ions, ILs are remarkably tunable and diverse as cations and anions can be mixed and matched to yield desired properties. Because of this, IL/water systems range widely—from homogeneous mixtures to multiphasic systems featuring ionic liquid/liquid interfaces. Even more diversity is added when particles are introduced to these systems, as hard particles or soft-matter microgels interact with both ILs and water in complex ways. This work examines both miscible ionic liquid/water mixture and two-phase, immiscible ionic liquid/water systems. Extensive molecular dynamics (MD) simulations are utilized in conjunction with physical measurements to inform theoretical understanding of the nature of these systems, and this theoretical understanding is related to practical applications—in particular, the development of a low-temperature liquid electrolyte for use in molecular electronic transducer (MET) seismometers, and particle self-assembly and transport at ionic liquid/liquid interfaces such as those in Pickering emulsions.
The homogenous mixture of 1-butyl-3-methylimidazolium iodide and water is examined extensively through MD as well as physical characterization of properties. Molecular ordering within the liquid mixture is related to macroscopic properties. These mixtures are then used as the basis of an electrolyte with unusual characteristics, specifically a wide liquid temperature range with an extremely low lower bound combined with relatively low viscosity allowing excellent performance in the MET sensor. Electrolyte performance is further improved by the addition of fullerene nanoparticles, which dramatically increase device sensitivity. The reasons behind this effect are explored by testing the effect of graphene surface size and through MD simulations of fullerene and a silica nanoparticle (for contrast) in [BMIM][I]/water mixtures.
Immiscible ionic liquid/water systems are explored through MD studies of particles at IL/water interfaces. By increasing the concentration of hydrophobic nanoparticles at the IL/water interface, one study discovers the formation of a commingled IL/water/particle pseudo-phase, and relates this discovery to previously-observed unique behaviors of these interfaces, particularly spontaneous particle transport across the interface. The other study demonstrates that IL hydrophobicity can influence the deformation of thermo-responsive soft particles at the liquid/liquid interface.
The homogenous mixture of 1-butyl-3-methylimidazolium iodide and water is examined extensively through MD as well as physical characterization of properties. Molecular ordering within the liquid mixture is related to macroscopic properties. These mixtures are then used as the basis of an electrolyte with unusual characteristics, specifically a wide liquid temperature range with an extremely low lower bound combined with relatively low viscosity allowing excellent performance in the MET sensor. Electrolyte performance is further improved by the addition of fullerene nanoparticles, which dramatically increase device sensitivity. The reasons behind this effect are explored by testing the effect of graphene surface size and through MD simulations of fullerene and a silica nanoparticle (for contrast) in [BMIM][I]/water mixtures.
Immiscible ionic liquid/water systems are explored through MD studies of particles at IL/water interfaces. By increasing the concentration of hydrophobic nanoparticles at the IL/water interface, one study discovers the formation of a commingled IL/water/particle pseudo-phase, and relates this discovery to previously-observed unique behaviors of these interfaces, particularly spontaneous particle transport across the interface. The other study demonstrates that IL hydrophobicity can influence the deformation of thermo-responsive soft particles at the liquid/liquid interface.
ContributorsNickerson, Stella Day (Author) / Dai, Lenore L (Thesis advisor) / Yu, Hongyu (Committee member) / Lind, Mary Laura (Committee member) / Mu, Bin (Committee member) / Emady, Heather (Committee member) / Arizona State University (Publisher)
Created2016