Matching Items (39)

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Solution-Cast Membranes for Wastewater Recovery: A New Chemical-Resistant Nanocomposite Design

Description

The goal of this research project is to create a mixed matrix membrane that can withstand very acidic environments but still be used to purify water. The ultimate goal of

The goal of this research project is to create a mixed matrix membrane that can withstand very acidic environments but still be used to purify water. The ultimate goal of this membrane is to be used to purify urine both here on Earth and in space. The membrane would be able to withstand these harsh conditions due the incorporation of a resilient impermeable polymer layer that will be cast above the lower hydrophilic layer. Nanoparticles called zeolites will act as a water selective pathway through this impermeable layer and allow water to flow through the membrane. This membrane will be made using a variety of methods and polymers to determine both the cheapest and most effective way of creating this chemical resistant membrane. If this research is successful, many more water sources can be tapped since the membranes will be able to withstand hard conditions. This document is primarily focused on our progress on the development of a highly permeable polymer-zeolite film that makes up the bottom layer of the membrane. Multiple types of casting methods were investigated and it was determined that spin coating at 4000 rpm was the most effective. Based on a literature review, we selected silicalite-1 zeolites as the water-selective nanoparticle component dispersed in a casting solution of polyacrylonitrile in N-methylpyrrolidinone to comprise this hydrophilic layer. We varied the casting conditions of several simple solution-casting methods to produce thin films on the porous substrate with optimal film properties for our membrane design. We then cast this solution on other types of support materials that are more flexible and inexpensive to determine which combination resulted in the thinnest and most permeable film.

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Date Created
  • 2015-05

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LTA Zeolite Monolayers via the Langmuir-Blodgett Technique

Description

Zeolite thin films and membranes are currently a promising technology for pervaporation, gas separation and water purification. The main drawback with these technologies is that the synthesis is not consistent

Zeolite thin films and membranes are currently a promising technology for pervaporation, gas separation and water purification. The main drawback with these technologies is that the synthesis is not consistent leading to varied and unreproducible results. The Langmuir-Blodgett technique is a robust method for transferring monolayers of molecules or crystals to a solid substrate. By measuring the surface pressure and controlling the area, reliable results can be achieved by transferring monolayers to different solid substrates. It has been shown previously that various types of zeolites can be functionalized and dispersed on the top of water. This is done by using an alcohol to form a hydrophobic coating on the surface of zeolite. The Langmuir-Blodgett can be used to create thin, compact films of zeolites for synthesizing and growing zeolite films. For the first reported time, cubic LTA Zeolites monolayers have been assembled with the Langmuir-Blodgett technique with multiple solvents and different sizes of zeolites. These films were characterized with Scanning Electron Microscopy and Pressure-Area Isotherms generated from the Langmuir-Blodgett. It was found that linoleic acid is a required addition to the zeolite dispersions to protect the mechanical stability during agitation. Without this addition, the LTA zeolites are broken apart and lose their characteristic cubic structure. This effect is discussed and a theory is presented that the interparticle interactions of the long alkane chain of the linoleic acid help reduce the shear stress on the individual zeolite particles, thus preventing them from being broken. The effect of size of the zeolites on the monolayer formation was also discussed. There seemed to be little correlation between the monolayer quality and formation as size was changed. However, to optimize the process, different concentrations and target pressures are needed. Lastly, the effect of the solvent was explored and it was found that there is a different between monolayer formations for different solvents likely due to differing interparticle interactions. Overall, LTA zeolites were successfully fabricated and the important factors to consider are the zeolite size, the solvent, and the amount of surfactant stabilizer added.

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Date Created
  • 2016-12

Membrane modification for sensing urine biomarker levels

Description

Acute Kidney Injury (AKI) may be detected through biomarkers in urine. This research is being done to develop a membrane for use in separating urine biomarkers to monitor their level.

Acute Kidney Injury (AKI) may be detected through biomarkers in urine. This research is being done to develop a membrane for use in separating urine biomarkers to monitor their level. A hydrophobic membrane was treated to improve separation of the desired biomarker for colorimetric sensing. This method was tested with model solutions containing the biomarker. Future work will extend to testing with real urine.

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Date Created
  • 2017-05

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Photocurable Networks: A Composite Materials Platform that Enables Advances in Additive Manufacturing

Description

This study aims to provide a foundation for future work on photo-responsive polymer composite materials to be utilized in additive manufacturing processes. The curing rate of 2,2-dimethoxy-2-phenyl-acetophenone (DMPA) in

This study aims to provide a foundation for future work on photo-responsive polymer composite materials to be utilized in additive manufacturing processes. The curing rate of 2,2-dimethoxy-2-phenyl-acetophenone (DMPA) in thin (<20 µm) and thick (>2 mm) layers of DMPA and poly(ethylene glycol) diacrylate (PEG-DA) mixtures was assessed for 5.0 w/v% (grams per 100 mL) concentrations of DMPA dissolved in PEG-DA. The polymerization rate and quality of curing was found to decrease as the concentration of DMPA increased beyond 1.0 w/v%; thus, confirming the existence of an optimum photo-initiator concentration for a specific sheet thickness. The optimum photo-initiator concentration for a 3-3.1 mm thick sheet of PEG-DA microstructure was determined to be between 0.3 and 0.38 w/v% DMPA. The addition of 1,6-hexanediol or 1,3-butanediol to the optimum photo-initiator concentrated solution of DMPA and PEG-DA was found to increase the Tg of the samples; however, the samples could not fully cure within 40-50 s, which suggested a decrease in polymerization rate. Lastly, the DMPA photo-initiator does not produce gaseous byproducts and is translucent when fully cured, which makes it attractive for infusion with strengthening materials because quality light penetration is paramount to quick polymerization rates. It is recommended that more trials be conducted to evaluate the mechanical properties of the optimum curing rate for DMPA and PEG-DA microstructures as well as a mechanical property comparison following the addition of either of the two alcohols.

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Date Created
  • 2016-12

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Stabilization of Zeolite Particles on Microporous Support Membranes with Spin Coating Method for Thin Film Nanocomposite Membranes

Description

Even though access to purified water has improved, there are still many people and locations that do not have this convenience. Approximately 1.2 billion people lack access to safe drinking

Even though access to purified water has improved, there are still many people and locations that do not have this convenience. Approximately 1.2 billion people lack access to safe drinking water and 2.6 billion people have little or no sanitation. Furthermore, breakthroughs in water purification technology are essential to combat these issues. While there are several approaches to water purification, membrane processes are widely used based on their numerous advantages, including high operating temperature and low energy input. In essence, membranes do not require chemical additives, thermal inputs, or regeneration of spent media. The spin coating procedure was used to make a total of 94 membrane samples by adjusting the following variables: membrane support, membrane wetting, solvent, polyacrylonitrile (PAN) content, water contant, Linde Type A (LTA) zeolite content, and the rotations per minute (RPM) of the spin coater. Parameters that were held constant include PAN for the permeable dispersion layer, LTA zeolites as the inorganic filler material, and a spin time of 30 seconds for the spin coater. There were key findings in both the preliminary and core data sets. From the preliminary membrane samples 1 \u2014 40, a baseline was established to use for the core data: polysulfone (PSf) support, 1 \u2014 3% PAN content, and 1 \u2014 3% LTA zeolite content. Flux analysis revealed many inconsistencies in groups 1 \u2014 13 such as unreasonably high error bars (+50%), flow rates that were near zero or extremely high (+15,000 L hr-1 m-2), and lack of a clear trend for membrane specifications. Membranes with a high degree of polymer \u2014 zeolite aggregation on the surface had very low flux values. A higher flux of 4,700 L hr-1 m-2 was correlated to gap and hole formation on the membrane surface. It was shown in group 7 that an increasing degree of surface defects corresponded to an increasing flux of 17,000 L hr-1 m-2. Although the target flux for a defect \u2014 free membrane lies between 500 \u2014 4,000 L hr-1 m-2, there were not any groups with flux values in this range. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) analysis revealed that the observed group similarities could not be attributed to individual membrane specifications. However, this data showed chemical fingerprint overlap across all groups, which were synthesized with varying quantities of the same chemicals. Analysis of flux data, SEM images, and ATR-FTIR data all suggest that the spin coating procedure leads to inconsistent results. Although the spin coater provides flexibility in user control, its advantages are outweighed by the limited control of surface uniformity, zeolite dispersion, and defect formation. It has been shown that the spin coating process is not compatible with the formation of a uniform polymer \u2014 zeolite layer in these experiments.

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Date Created
  • 2016-12

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Development of ductile, amorphous metallic film at ambient conditions

Description

The overall goal of this project is to use metallic nanoparticles to develop a thin, ductile amorphous film at room temperature. Currently bulk metallic glasses are mainly formed via quenching,

The overall goal of this project is to use metallic nanoparticles to develop a thin, ductile amorphous film at room temperature. Currently bulk metallic glasses are mainly formed via quenching, which requires very high cooling rates to achieve an amorphous molecular structure. These formations often fail in a brittle manner. The advantages of using a bottom-up approach with amorphous nanoparticles at ambient conditions is that the ductility of the metal can be improved, and the process will be less energy intensive. The nanoparticles used are iron precursors with ATMP and DTPMP ligand stabilizers and dispersed in methanol. Three forms of experimentation were applied over the course of this project. The first was a simple, preliminary data collection approach where the particles were dispersed onto a glass slide and left to dry under various conditions. The second method was hypersonic particle deposition, which accelerated the particles to high speeds and bombarded onto a glass or silicon substrate. The third method used Langmuir-Blodgett concepts and equipment to make a film. Qualitative analyses were used to determine the efficacy of each approach, including SEM imaging. In the end, none of the approaches proved successful. The first approach showed inconsistencies in the film formation and aggregation of the particles. The results from the hypersonic particle deposition technique showed that not enough particles were deposited to make a consistent film, and many of the particles that were able to be deposited were aggregated. The Langmuir-Blodgett method showed potential, but aggregation of the particles and uneven film formation were challenges here as well. Although there are ways the three discussed experimental approaches could be optimized, the next best step is to try completely new approaches, such as convective assembly and 3D printing to form the ideal nanoparticle film.

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Date Created
  • 2016-12

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Model Membrane System to Determine Water Permeability of Linde Type A Zeolite

Description

In this research, construction of a model membrane system using Polyvinylidene Chloride-Co Acrylonitrile and Linde Type A zeolites is described. The systems aims to separate out flow through zeolite pores

In this research, construction of a model membrane system using Polyvinylidene Chloride-Co Acrylonitrile and Linde Type A zeolites is described. The systems aims to separate out flow through zeolite pores and flow through interfaces between zeolites and polymers through the use of pore filled and pore open zeolites. Permeation tests and salt rejection tests were performed, and the data analyzed to yield approximation of separated flow through zeolites and interfaces. This work concludes the more work is required to bring the model system into a functioning state. New polymer selections and new techniques to produce the membrane system are described for future work.

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Date Created
  • 2014-05

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Experiments in Science Education: How In-Classroom Demonstrations and Hands-On Activities Affect Student Interest in Science and Engineering

Description

This thesis aims to evaluate how in classroom demonstrations compare to regular education techniques, and how student learning styles affect interest in science and engineering as future fields of study.

This thesis aims to evaluate how in classroom demonstrations compare to regular education techniques, and how student learning styles affect interest in science and engineering as future fields of study. Science education varies between classrooms, but usually is geared towards lecture and preparation for standardized exams without concern for student interest or enjoyment.5 To discover the effectiveness of demonstrations in these concerns, an in classroom demonstration with a water filtration experiment was accompanied by several modules and followed by a short survey. Hypotheses tested included that students would enjoy the demonstration more than a typical class session, and that of these students, those with more visual or tactile learning styles would identify with science or engineering as a possible major in college. The survey results affirmed the first hypothesis, but disproved the second hypothesis; thus illustrating that demonstrations are enjoyable, and beneficial for sparking or maintaining student interest in science across all types of students.

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Date Created
  • 2014-05

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Synthesis and Characterization of Thin Supported PDMS/ZIF-71 Films for Pervaporative Biofuel Recovery

Description

The recovery of biofuels permits renewable alternatives to present day fossil fuels that cause devastating effects on the planet. Pervaporation is a separation process that shows promise for the separation

The recovery of biofuels permits renewable alternatives to present day fossil fuels that cause devastating effects on the planet. Pervaporation is a separation process that shows promise for the separation of ethanol from biologically fermentation broths. The performance of thin film composite membranes of polydimethylsiloxane (PDMS) and zeolite imidazolate frameworks (ZIF-71) dip coated onto a porous substrate are analyzed. Pervaporation performance factors of flux, separation factor and selectivity are measured for varying ZIF-71 loadings of pure PDMS, 5 wt%, 12.5 wt% and 25 wt% at 60 oC with a 2 wt% ethanol/water feed. The increase in ZIF-71 loadings increased the performance of PDMS to produce higher flux, higher separation factor and high selectivity than pure polymeric films.

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Date Created
  • 2014-05

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Characterizing the Effects of Various Acids on Zeolites

Description

This project is part of a larger project involving making membranes for the separation of potable water from urine solutions for applications in space travel. This project deals specifically with

This project is part of a larger project involving making membranes for the separation of potable water from urine solutions for applications in space travel. This project deals specifically with testing LTA nanozeolites that will be used in the membrane under a variety of acidic conditions, specifically in solutions of sulfuric acid, chromium trioxide, and potassium phosphate of pHs ranging from .5 to 5, in order to investigate the effects of pH, acid type, and time. They were analyzed using SEM, FTIR, and XRD, in order to analyze how much the zeolite was degraded under the conditions of each solution. It was determined that, for high pH values (4-5), potassium phosphate had the strongest effect, as it degraded the zeolite to the point of destroying the crystal structure completely. Because of the solubility limit of potassium phosphate in water, it could not be analyzed at low pH, so only sulfuric acid and chromium trioxide were analyzed at low pH (.5-3). They both had severe effects, sulfuric acid being slightly more severe, with both of them completely dissolving the zeolite at pH values of 1 and lower. Decreasing pH increased degradation for all of the acids, with pH values above 2 for sulfuric acid and chromium trioxide showing only minor degradation, and pH 5 potassium phosphate showing only minor degradation.

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  • 2013-05