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Computational Modeling and Experimentation of Pervaporation Membrane Processes for Brackish Water Recovery

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Fresh water is essential to the human population and is an integral component in global economics for its multiple uses, and population growth/development cause concern for the possible exhaustion of the limited supply of freshwater. A combined computational and experimental

Fresh water is essential to the human population and is an integral component in global economics for its multiple uses, and population growth/development cause concern for the possible exhaustion of the limited supply of freshwater. A combined computational and experimental approach to observe and evaluate pervaporation membrane performance for brackish water recovery was done to assess its efficiency and practicality for real world application. Results from modeling conveyed accuracy to reported parameter values from literature as well as strong dependence of performance on input parameters such as temperature. Experimentation results showed improved performance in flux by 34%-42% with radiative effect and then additional performance improvement (9%-33%) with the photothermal effect from carbon black application. Future work will include improvements to the model to include scaling propensity and energy consumption as well as continued experimentation to assess quality of pervaporation in water recovery.

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2018-05

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Mass Transfer Kinetics of Novel Asymmetric Hollow-fiber Membranes

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This report investigates the mass-transfer kinetics of gas diffusion through an asymmetrical hollow-fiber membrane developed for the membrane biofilm reactor (MBfR) when it is used to microbiologically convert syngas (a mixture of H2, CO2, and CO) to organic products.

This report investigates the mass-transfer kinetics of gas diffusion through an asymmetrical hollow-fiber membrane developed for the membrane biofilm reactor (MBfR) when it is used to microbiologically convert syngas (a mixture of H2, CO2, and CO) to organic products. The asymmetric Matrimid® membrane had superior diffusion fluxes compared to commercially available symmetric, three-layer composite and polypropylene single-layer membranes. The Matrimid® asymmetric membrane had a H2 gas-gas diffusion flux between 960- and 1600-fold greater than that of the composite membrane and between 32,000- and 46,800-fold greater than that of the single-layer membrane. Gas-gas diffusion experiments across the Matrimid® membrane also demonstrated plasticization behavior for pure CO2 and H2 gas feeds. In particular, a 10 psia increase in inlet pressure resulted in a 12-fold increase in permeance for H2 and a 16-fold increase for CO2. Plasticization was minimal for symmetric composite and single-layer membranes. Thus, diffusion fluxes were much higher for the asymmetric membrane than for the symmetric composite and single-layer membranes, and this supports the promise of the asymmetric membrane as a high-efficiency means to deliver syngas to biofilms able to convert the syngas to organic products. Gas-liquid diffusion was much slower than gas-gas diffusion, and this supports the benefit of using the MBfR approach over fermentation reactors that rely on sparging syngas.

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2018-05

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Backend Construction of a Web Service

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A growing number of stylists \u2014 cosmetologists \u2014 are finding it harder to afford the basic necessities such as rent. However, the ever-increasing presence of smartphones and the increasing need for on-demand services like Uber and Uber Eats creates a

A growing number of stylists \u2014 cosmetologists \u2014 are finding it harder to afford the basic necessities such as rent. However, the ever-increasing presence of smartphones and the increasing need for on-demand services like Uber and Uber Eats creates a unique opportunity for stylists \u2014 Clippr. Clippr is an application that aims to connect individual stylists directly to their customers. The application gives stylists a platform to create and display their own prices, services, and portfolio. Customers get the benefit of finding a stylist that suits them and booking instantly. This project outlines the backend for the Clippr application. It goes over the framework, REST API, and various functionalities of the application. Additionally, the project also covers the work that is still needed to successfully launch the application.

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2017-05

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Construction and Operation of a Hollow Fiber Membrane Spinning Apparatus

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This study details the construction and operation of a dry-jet wet spinning apparatus for extruding hollow fiber membranes (HFMs). The main components of the apparatus are a spinneret, a coagulation bath, and an automatic collection reel. Continuous fiber formation was

This study details the construction and operation of a dry-jet wet spinning apparatus for extruding hollow fiber membranes (HFMs). The main components of the apparatus are a spinneret, a coagulation bath, and an automatic collection reel. Continuous fiber formation was achieved using two syringe pumps simultaneously delivering polymer dope and bore fluid to the spinneret. Based on apparatus runs performed with Polysulfone (PSF) dopes dissolved in N,N-Dimethylacetamide and supporting rheological analysis, the entanglement concentration, ce, was identified as a minimum processing threshold for creating HFMs. Similarly, significant increases in the ultimate tensile strength, fracture strain, and Young's modulus for extruded HFMs were observed as polymer dope concentration was increased at levels near ce. Beyond this initial increase, subsequent tests at higher PSF concentrations yielded diminishing changes in mechanical properties, suggesting an asymptotic approach to a point where the trend would cease. Without further research, it is theorized that this point falls on a transition from the semidiute entangled to concentrated concentration regimes. SEM imaging of samples revealed the formation of grooved structures on the inner surface of samples, which was determined to be a result of the low flowrate and polymer dope concentrations used in processing the HFMs during apparatus runs. Based on continued operation of the preliminary apparatus design, many areas of improvement were noted. Namely, these consisted of controlling the collector speed, eliminating rubbing of nascent fibers against the edge of the coagulation bath by installing an elevated roller, and replacing tygon tubing for the polymer line with a luer lock adapter for direct syringe attachment to the spinneret.

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2017-05

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. A hydrophobic membrane was treated to improve separation of the

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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2017-05

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A Stability Study of the MOF-5 Membrane

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Within recent years, metal-organic frameworks, or MOF’s, have gained a lot of attention in the materials research community. These micro-porous materials are constructed of a metal oxide core and organic linkers, and have a wide-variety of applications due to their

Within recent years, metal-organic frameworks, or MOF’s, have gained a lot of attention in the materials research community. These micro-porous materials are constructed of a metal oxide core and organic linkers, and have a wide-variety of applications due to their extensive material characteristic possibilities. The focus of this study is the MOF-5 material, specifically its chemical stability in air. The MOF-5 material has a large pore size of 8 Å, and aperture sizes of 15 and 12 Å. The pore size, pore functionality, and physically stable structure makes MOF-5 a desirable material. MOF-5 holds applications in gas/liquid separation, catalysis, and gas storage. The main problem with the MOF-5 material, however, is its instability in atmospheric air. This inherent instability is due to the water in air binding to the zinc-oxide core, effectively changing the material and its structure. Because of this material weakness, the MOF-5 material is difficult to be utilized in industrial applications. Through the research efforts proposed by this study, the stability of the MOF-5 powder and membrane were studied. MOF-5 powder and a MOF-5 membrane were synthesized and characterized using XRD analysis. In an attempt to improve the stability of MOF-5 in air, methyl groups were added to the organic linker in order to hinder the interaction of water with the Zn4O core. This was done by replacing the terepthalic acid organic linker with 2,5-dimethyl terephthalic acid in the powder and membrane synthesis steps. The methyl-modified MOF-5 powder was found to be stable after several days of exposure to air while the MOF-5 powder exhibited significant crystalline change. The methyl-modified membrane was found to be unstable when synthesized using the same procedure as the MOF-5 membrane.

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2016-05

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Bi-phase Synthesis of the Zirconium Metal-Organic Framework, UiO-66

Description

Metal-organic frameworks (MOFs) are a new set of porous materials comprised of metals or metal clusters bonded together in a coordination system by organic linkers. They are becoming popular for gas separations due to their abilities to be tailored toward

Metal-organic frameworks (MOFs) are a new set of porous materials comprised of metals or metal clusters bonded together in a coordination system by organic linkers. They are becoming popular for gas separations due to their abilities to be tailored toward specific applications. Zirconium MOFs in particular are known for their high stability under standard temperature and pressure due to the strength of the Zirconium-Oxygen coordination bond. However, the acid modulator needed to ensure long range order of the product also prevents complete linker deprotonation. This leads to a powder product that cannot easily be incorporated into continuous MOF membranes. This study therefore implemented a new bi-phase synthesis technique with a deprotonating agent to achieve intergrowth in UiO-66 membranes. Crystal intergrowth will allow for effective gas separations and future permeation testing. During experimentation, successful intergrown UiO-66 membranes were synthesized and characterized. The degree of intergrowth and crystal orientations varied with changing deprotonating agent concentration, modulator concentration, and ligand:modulator ratios. Further studies will focus on achieving the same results on porous substrates.

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2016-12

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

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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

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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2014-05

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Effects of Aging and Crystallization Time and Temperature in the Synthesis of Ideal Zeolite Linde Type A

Description

One of the grand challenges of engineering is to provide access to clean water because it is predicted that by 2025 more than two thirds of the world’s population will face severe water shortages. To combat this global issue,

One of the grand challenges of engineering is to provide access to clean water because it is predicted that by 2025 more than two thirds of the world’s population will face severe water shortages. To combat this global issue, our lab focuses on creating a novel composite membrane to recover potable water from waste. For use as the water-selective component in this membrane design Linde Type A zeolites were synthesized for optimal size without the use of a template. Current template-free synthesis of zeolite LTA produces particles that are too large for our application therefore the particle size was reduced in this study to reduce fouling of the membrane while also investigating the nanoparticle synthesis mechanisms. The time and temperature of the reaction and the aging of the precursor gel were systematically modified and observed to determine the optimal conditions for producing the particles. Scanning electron microscopy, x-ray diffraction, and energy dispersive x-ray analysis were used for characterization. Sub-micron sized particles were synthesized at 2 weeks aging time at -8°C with an average size of 0.6 micrometers, a size suitable for our membrane. There is a limit to the posterity and uniformity of particles produced from modifying the reaction time and temperature. All results follow general crystallization theory. Longer aging produced smaller particles, consistent with nucleation theory. Spinodal decomposition is predicted to affect nucleation clustering during aging due to the temperature scheme. Efforts will be made to shorten the effective aging time and these particles will eventually be incorporated into our mixed matrix osmosis membrane.

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2016-05

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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 of ethanol from biologically fermentation broths. The performance of thin

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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2014-05