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Description
Membranes are a key part of pervaporation processes, which is generally a more

efficient process for selective removal of alcohol from water than distillation. It is

necessary that the membranes have high alcohol permeabilities and selectivities.

Polydimethylsiloxane (PDMS) based mixed matrix membranes (MMMs) have

demonstrated very promising results. Zeolitic imidazolate framework-71 (ZIF-71)

demonstrated promising alcohol

Membranes are a key part of pervaporation processes, which is generally a more

efficient process for selective removal of alcohol from water than distillation. It is

necessary that the membranes have high alcohol permeabilities and selectivities.

Polydimethylsiloxane (PDMS) based mixed matrix membranes (MMMs) have

demonstrated very promising results. Zeolitic imidazolate framework-71 (ZIF-71)

demonstrated promising alcohol separation abilities. In this dissertation, we present

fundamental studies on the synthesis of ZIF-71/PDMS MMMs.

Free-standing ZIF-71/ PDMS membranes with 0, 5, 25 and 40 wt % ZIF-71

loadings were prepared and the pervaporation separation for ethanol and 1-butanol from

water was measured. ZIF-71/PDMS MMMs were formed through addition cure and

condensation cure methods. Addition cure method was not compatible with ZIF-71

resulting in membranes with poor mechanical properties, while the condensation cure

method resulted in membranes with good mechanical properties. The 40 wt % ZIF-71

loading PDMS nanocomposite membranes achieved a maximum ethanol/water selectivity

of 0.81 ± 0.04 selectivity and maximum 1-butnaol/water selectivity of 5.64 ± 0.15.

The effects of synthesis time, temperature, and reactant ratio on ZIF-71 particle

size and the effect of particle size on membrane performance were studied. Temperature

had the greatest effect on ZIF-71 particle size as the synthesis temperature varied from -

20 to 35 ºC. The ZIF-71 synthesized had particle diameters ranging from 150 nm to 1

μm. ZIF-71 particle size is critical in ZIF-71/PDMS composite membrane performance

for alcohol removal from water through pervaporation. The membranes made with

micron sized ZIF-71 particles showed higher alcohol/water selectivity than those with

smaller particles. Both alcohol and water permeability increased when larger sized ZIF-

71 particles were incorporated.

ZIF-71 particles were modified with four ligands through solvent assisted linker

exchange (SALE) method: benzimidazole (BIM), 5-methylbenzimidazole (MBIM), 5,6-

dimethylbenzimidazole (DMBIM) and 4-Phenylimidazole (PI). The morphology of ZIF-

71 were maintained after the modification. ZIF-71/PDMS composite membranes with 25

wt% loading modified ZIF-71 particles were made for alcohol/water separation. Better

particle dispersion in PDMS polymer matrix was observed with the ligand modified ZIFs.

For both ethanol/water and 1-butanol/water separations, the alcohol permeability and

alcohol/water selectivity were lowered after the ZIF-71 ligand exchange reaction.
ContributorsYin, Huidan (Author) / Lind, Mary Laura (Thesis advisor) / Mu, Bin (Committee member) / Nielsen, David (Committee member) / Seo, Don (Committee member) / Lin, Jerry (Committee member) / Arizona State University (Publisher)
Created2017
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Description
Currently, approximately 40% of the world’s electricity is generated from coal and coal power plants are one of the major sources of greenhouse gases accounting for a third of all CO2 emissions. The Integrated Gasification Combined Cycle (IGCC) has been shown to provide an increase in plant efficiency compared

Currently, approximately 40% of the world’s electricity is generated from coal and coal power plants are one of the major sources of greenhouse gases accounting for a third of all CO2 emissions. The Integrated Gasification Combined Cycle (IGCC) has been shown to provide an increase in plant efficiency compared to traditional coal-based power generation processes resulting in a reduction of greenhouse gas emissions. The goal of this project was to analyze the performance of a new SNDC ceramic-carbonate dual-phase membrane for CO2 separation. The chemical formula for the SNDC-carbonate membrane was Sm0.075Nd0.075Ce0.85O1.925. This project also focused on the use of this membrane for pre-combustion CO2 capture coupled with a water gas shift (WGS) reaction for a 1000 MW power plant. The addition of this membrane to the traditional IGCC process provides a purer H2 stream for combustion in the gas turbine and results in lower operating costs and increased efficiencies for the plant. At 900 °C the CO2 flux and permeance of the SNDC-carbonate membrane were 0.65 mL/cm2•min and 1.0×10-7 mol/m2•s•Pa, respectively. Detailed in this report are the following: background regarding CO2 separation membranes and IGCC power plants, SNDC tubular membrane preparation and characterization, IGCC with membrane reactor plant design, process heat and mass balance, and plant cost estimations.
ContributorsDunteman, Nicholas Powell (Author) / Lin, Jerry (Thesis director) / Dong, Xueliang (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor) / School of Sustainability (Contributor)
Created2014-05
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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

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.
ContributorsLai, Tianmiao (Author) / Lind, Mary Laura (Thesis advisor) / Lin, Jerry (Committee member) / Li, Jian (Committee member) / Arizona State University (Publisher)
Created2015
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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)

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.
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
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Description

In 2019, the World Health Organization stated that climate change and air pollution is the greatest growing threat to humanity. With a world population of close to 8 billion people, the rate of population growth continues to increase nearly 1.05% each year. As the world population grows, carbon dioxide emissions

In 2019, the World Health Organization stated that climate change and air pollution is the greatest growing threat to humanity. With a world population of close to 8 billion people, the rate of population growth continues to increase nearly 1.05% each year. As the world population grows, carbon dioxide emissions and climate change continue to accelerate. By observing increasing concentrations of greenhouse gas emissions in the atmosphere, scientists have correlated that the Earth’s temperature is increasing at an average rate of 0.13 degrees Fahrenheit each decade. In an effort to mitigate and slow climate change engineers across the globe have been eagerly seeking solutions to fight this problem. A new form of carbon dioxide mitigation technology that has begun to gain traction in the last decade is known as direct air capture (DAC). Direct air capture works by removing excess atmospheric carbon dioxide from the air and repurposing it. The major challenge faced with DAC is not capturing the carbon dioxide but finding a useful way to reuse the post-capture carbon dioxide. As part of my undergraduate requirements, I was tasked to address this issue and create my own unique design for a DAC system. The design was to have three major goals: be 100% self-sufficient, have net zero carbon emissions, and successfully repurpose excess carbon dioxide into a sustainable and viable product. Arizona was chosen for the location of the system due to the large availability of sunlight. Additionally, the design was to utilize a protein rich hydrogen oxidizing bacteria (HOB) known as Cupriavidus Necator. By attaching a bioreactor to the DAC system, excess carbon dioxide will be directly converted into a dense protein biomass that will be used as food supplements. In addition, my system was designed to produce 1 ton (roughly 907.185 kg) of protein in a year. Lastly, by utilizing solar energy and an atmospheric water generator, the system will produce its own water and achieve the goal of being 100% self-sufficient.

ContributorsMacIsaac, Ian (Author) / Lin, Jerry (Thesis director) / Ovalle-Encinia, Oscar (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor) / Historical, Philosophical & Religious Studies, Sch (Contributor)
Created2022-05
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Description
This study deals with various flow field designs for anode, cathode, and coolant plates for optimizing the performance of proton exchange membrane fuel cell using H2 and air. In particular, the 3D models with various flow field patterns such as single parallel serpentine (anode), multi parallel (anode), multi-parallel serpentine (cathode),

This study deals with various flow field designs for anode, cathode, and coolant plates for optimizing the performance of proton exchange membrane fuel cell using H2 and air. In particular, the 3D models with various flow field patterns such as single parallel serpentine (anode), multi parallel (anode), multi-parallel serpentine (cathode), multi serpentine (cathode) have been evaluated for enhancing the fuel cell performance at 60 oC, with three different coolant flow designs (mirror serpentine, multi serpentine and parallel serpentine). Both the peak power and limiting current density are considered based on the parameters such as temperature distribution, pressure distribution, reactants/species distribution and the membrane water content on the active area (50 cm2) region. It is interesting to note that the coolant channel also has a significant effect in regulating the fuel cell performance at high current densities, in addition to reactant gas flow channels. The simulated single cell with Nafion (thickness: 18 m) demonstrates a peak power density of 0.97 W.cm-2 with single parallel serpentine (anode), multi parallel serpentine (cathode) and serpentine (coolant) and 0.91 W.cm-2 with multi parallel (anode), multi serpentine (cathode), and parallel serpentine (coolant) flow field designs. The simulated fuel cell performance is also experimentally validated with four cells at 60 oC using H2 fuel and air as the oxidant.
ContributorsAhmed, Rafiq (Author) / Mada Kannan, Arunachala (Thesis advisor) / Torres, Cesar (Committee member) / Lin, Jerry (Committee member) / Arizona State University (Publisher)
Created2023