Engineering Commons^™

Biphasic Cellulose Acetate/Rtil Membranes And Functionalized Graphene Adsorbents For Natural Gas Processing: Experimental And Molecular Simulation Studies, Amir Khakpay

Electronic Theses and Dissertations

In this dissertation, gas separation using membranes is investigated for natural gas upgrading. The main objectives of this study are separation of high value hydrocarbons such as propane (c3h8) from natural gas and carbon dioxide (co2) separation from light gases such as nitrogen (n2) and methane (ch4). To achieve these goals, supported ionic liquid membranes (silms), biphasic membranes, and nanoporous graphene (npg) and graphene oxide (npgo) membranes are studied. Biphasic membranes are proposed to overcome silms issues for gas separation. The major issues with silms are low room temperature ionic liquid (rtil) content and instability at high cross-membrane pressure. For …

Stability And Retention Enhancement Of Low Fouling Polystyrene Sulfonic Acid (Pss) And Polyethylene Glycol (Peg) Blend Films With Silane Coupling Agents, Sean Stybel

Williams Honors College, Honors Research Projects

The goal of this research project was to apply silane coupling agents for enhanced stability and retention of a low fouling polymeric coating to an inorganic substrate. A blend of polystyrene sulfonic acid (PSS) and polyethylene glycol (PEG) was crosslinked in order to create a low fouling film. The film was prepared by spin coating a PSS-PEG solution on an inorganic substrate coated with a layer of a silane coupling agent (3-aminopropyltriethoxysilane, APTES, solution), followed by thermal curing. The research was limited to less than one year and only used lab equipment available at the University of Akron. Stability and …

Crumpled Graphene Oxide: Aerosol Synthesis And Environmental Applications, Yi Jiang

McKelvey School of Engineering Theses & Dissertations

Environmental technologies, such as for water treatment, have advanced significantly due to the rapid expansion and application of nanoscale material science and engineering. In particular, two-dimensional graphene oxide (GO), has demonstrated considerable potential for advancing and even revolutionizing some of these technologies, such as engineered photocatalysts and membranes. To realize such potential, an industrially scalable process is needed to produce monomeric and aggregation-resistant GO nanostructures/composites, in addition to new knowledge of material properties, behavior, and performance within an environmental context.

Research presented in this thesis addresses both scientific and engineering gaps through the development of a simple, yet robust aerosol-based …

Mass And Charge Transport In Hydrated Polymeric Membranes, Marshall T. Mcdonnell

Doctoral Dissertations

Mass and charge transport through hydrated polymer membranes has significant importance for many areas of engineering and industry. Multi-scale modeling and simulation techniques were used to study transport in relation to two specific membrane applications: (1) food packaging and (2) additives for polymer electrolytes.

Chitosan/chitin films were studied due to their use as a sustainable, biodegradable food packaging film. The effects of hydration on the solvation, diffusivity, solubility, and permeability of oxygen molecules in these films were studied via molecular dynamics and confined random walk simulations. With increasing hydration, the membrane was observed to have a more homogeneous water distribution …

Characterization Of Fibrin Matrix Incorporated Electrospun Polycaprolactone Scaffold, Cho Yi Wong

Theses and Dissertations

Specific objective: Guided tissue regeneration (GTR) aims to regenerate the lost attachment apparatus caused by periodontal disease through the use of a barrier membrane. For the GTR procedures to be successful, barrier membranes are required to be present at the surgical site for an extended period of time (weeks to months). Synthetic membranes have the advantage of prolonged presence in a wound site; however, they do not actively contribute to wound healing. Biologic membranes are recognized by the host tissue and participate in wound healing but have the disadvantage of early resorption. Therefore, the goal of this study is …

Effects Of Magnetically Induced Micro-Mixing On Nanofiltration Performance, Guanghui Song

Graduate Theses and Dissertations

Nanofiltration (NF) is a relatively new membrane separation process mainly used for removing low molecular weight species from aqueous and non-aqueous solutions. NF membranes suffer from concentration polarization leading to membrane fouling thus compromised membrane performance. Magnetically responsive nanofiltration (NF) membranes functionalized with superparamagnetic nanoparticles (SPNs) attached to the chain ends of grafted polymer nanolayers have been shown to be effective in breaking concentration polarization at the membrane-liquid interface under an appropriate external oscillating magnetic field. Under an oscillating magnetic field, the movement of the polymer chains acts as micro-mixer leading to the suppression of concentration polarization and improved filtration …

Modified Polysulfone Nanofiltration Membrane Synthesis For Hydraulic Fracturing Water Recycle, Blake Alexander Johnson

Graduate Theses and Dissertations

The use of hydraulic fracturing has resulted in significant increases in the yield of oil and natural gas, as water pumped into wells at high pressure cracks the formations and releases the hydrocarbons that are locked in the rocks. This process has created large volumes of brackish water that is very difficult to process and is often disposed of into injection wells. Suspended solids and some dissolved solids are more readily removed, but the multivalent ions found in certain salts can precipitate in a well and complicate the reuse of flowback in future hydraulic fracturing operations.

Nanofiltration, a membrane separation …

Long Term Blood Oxygenation Membranes, Joseph V. Alexander

Theses and Dissertations--Biomedical Engineering

Hollow fiber membranes are widely used in blood oxygenators to remove carbon dioxide and add oxygen during cardiopulmonary bypass operations. These devices are now widely used off-label by physicians to perform extracorporeal blood oxygenation for patients with lung failure. Unfortunately, the hollow fiber membranes used in these devices fail prematurely due to blood plasma leakage and gas emboli formation.

This project formed ultrathin (~100nm) polymer coatings on polymer hollow fiber membranes. The coatings were intended to “block” existing pores on the exterior surfaces while permitting high gas fluxes. This coating is synthesized using surface imitated control radical polymerization.

The coating …

Developing A Colorimetric Membrane Sensor To Detect Trihalomethanes In Water Samples Utilizing The Fujiwara Reaction, Max D. Duckworth

Williams Honors College, Honors Research Projects

This work focused on creating a colorimetric sensor to detect trihalomethanes (THMs) at concentrations near the level of environmental regulations from the environmental protection agency (EPA). This work utlized the fujiwara reaction as well as a hydrophobic electrospun polyprolylene membrane to produce a sensitive colorimetric reaction. A calibration curve was produced which was able to predict the concentration of a bromoroform solution in the range of 8-250 ppb with a confidence of 97.7 % using the intensity of the color change as a quantitative measure.

Novel Scrubbing Systems For Post-Combustion Co2 Capture And Recovery, Tripura Mulukutla

Dissertations

Power plant emissions of flue gas releases considerable CO₂ to the atmosphere; CO₂ is considered to be the main contributor to global warming. Several gas absorption techniques are being investigated to reduce the capital and operating costs for CO₂ capture from post-combustion flue gas. Conventional method of CO₂ capture by an aqueous solution of monoethanolamine (MEA) and its subsequent stripping in a separate tower with steam at 120°C, is a highly energy intensive process. The low partial pressure of CO₂ in the flue gas inhibits the application of CO₂-selective membranes unless methods are …

Oxygen Flux And Dielectric Response Study Of Mixed Ionic-Electronic Conducting (Miec) Heterogeneous Functional Materials, Fazle Rabbi

Theses and Dissertations

Dense mixed ionic-electronic conducting (MIEC) membranes consisting of ionic conductive perovskite-type and/or fluorite-type oxides and high electronic conductive spinel type oxides, at elevated temperature can play a useful role in a number of energy conversion related systems including the solid oxide fuel cell (SOFC), oxygen separation and permeation membranes, partial oxidization membrane reactors for natural gas processing, high temperature electrolysis cells, and others. This study will investigate the impact of different heterogeneous characteristics of dual phase ionic and electronic conductive oxygen separation membranes on their transport mechanisms, in an attempt to develop a foundation for the rational design of such …

Ultrathin Graphene Oxide Membranes/Coatings For Separations, Hang Li

Theses and Dissertations

Graphene oxide (GO) was utilized as a novel material for making ultrathin membranes for gas separation and for making functional coatings for nano-/ultra-filtration in oil/water separation. Fundamental separation mechanisms by ultrathin GO membranes/coatings and potential applications were explored. This work can be divided into three parts. In the first part, ultrathin GO membranes supported on flat and smooth anodic aluminum oxide (AAO) substrates, with thickness down to 1.8 nm, were prepared by a facile vacuum filtration method. The as-prepared GO membranes were then studied for single-gas permeation and hydrogen mixture separation. It was revealed that the separation mechanism for the …

Application Of Membrane Processes For Concentration And Separation Of Sugar Streams In Biofuel Production, Mohammadmahdi Malmali

Graduate Theses and Dissertations

The overall objective of this study was identification and development of a sugar concentration/separation membrane filtration unit to improve the bioconversion of lignocellulosic biomass into chemicals and fuels. This thesis is divided into three main parts. The first part is about our studies on the use of nanofiltration membranes for concentration of sugars in a lignocellulosic biomass hydrolysate. In addition, the feasibility of simultaneous removal of acetic acid, 5-(hydroxymethyl)furfural and furfural from the hydrolysate has also been investigated. The results obtained indicate that both concentration of sugars and removal of hydrolysis degradation products is feasible. However, careful selection of the …

Ab Initio Studies Of Proton Transport In Proton Exchange Membranes, Jeffrey Keith Clark

Doctoral Dissertations

A molecular-level understanding of the factors that contribute to transport properties of proton exchange membranes (PEMs) for fuel cell applications is needed to aid in the development of superior membrane materials. Ab initio electronic structure calculations were undertaken on various PEM ionomer fragments to explore the effects of local hydration, side chain connectivity, protogenic group separation, and specific side chain chemistry on proton dissociation and transfer at low hydration. Cooperative interactions between both intra- and inter-molecular acidic groups and hydrogen bond connectivity were found to enhance proton dissociation at very low degrees of hydration. The energetics associated with proton transfer …

Layer-By-Layer Assemblies For Membrane-Based Enzymatic Catalysis, Andrew R. Tomaino

Theses and Dissertations--Chemical and Materials Engineering

While considerable progress has been made towards understanding the effect that membrane-based layer-by-layer (LbL) immobilizations have on the activity and stability of enzymatic catalysis, detailed work is required in order to fundamentally quantify and optimize the functionalization and operating conditions that define these properties. This work aims to probe deeper into the nature of transport mechanisms by use of pressure-induced, flow-driven enzymatic catalysis of LbL-functionalized hydrophilized poly(vinyldiene) (PVDF)-poly(acrylic acid) (PAA)-poly(allylamine hydrochloride) (PAH)-glucose oxidase (GOx) membranes. These membranes were coupled in a sealed series following cellulose acetate (CA) membranes for the elimination of product accumulation within the feed-side solution during operation. …

Membrane And Performance Study In Polymer Electrolyte Membrane Fuel Cells And Hydrogen Bromine Redox Flow Batteries, Yujia Bai

Doctoral Dissertations

This dissertation represents the consideration of the problems of polymer electrolyte membrane fuel cells (PEMFC) and hydrogen-bromine redox flow batteries (RFB). Due to the importance of water management in PEMFCs, all the experiments were strictly controlled at different water hydration conditions. Water uptake and densities were measured for Nafion^® and a series of 3M ionomer membranes. The thermodynamics of water and polymer was analyzed based on water uptake experiment and calorimetry. Furthermore, partial molar volumes (PMV) of water/membrane system was defined for the first time and used to analyze the interaction between water and polymers. Three states of water …

The Effect Of Bi-Polar Plate And Membrane Materials On Water Transport In Pemfcs, Visarn Lilavivat

Theses and Dissertations

An analysis of liquid water transport and removal in Proton Exchange Membrane Fuel Cells (PEMFCs) as affected by different membranes and the geometry and surface roughness of bipolar plates on is presented. Four topics are considered. First, the channel dimension and shape of various flow fields have been shown to affect the cell performance and the uniformity in the distributions of current. Typical variations in the channel width, height, and undercut that may occur with manufactured metal plates are studied. These sample-to-sample variations and distributions are studied and compared with laboratory-scale graphite plates. The goal of the work is to …

The Effect Of Granular Activated Carbon Pretreatment And Sand Pretreatment On Microfiltration Of Greywater, David Christopher

All Theses

Around the world, water scarcity is driving people to practice water reuse. One form of water reuse is the recycling of greywater, which is household wastewater excluding toilet waste. With adequate treatment, greywater may be recycled onsite for applications that do not require potable water, such as irrigation or toilet flushing. Membrane filtration (including microfiltration (MF)) is one option for greywater treatment. The small footprint, modular nature, and predictable performance of MF make it an attractive option. However, direct MF of greywater can lead to rapid membrane fouling. This thesis investigated two possible pretreatments for reducing membrane fouling and improving …

Artificial Alveolar-Capillary Membrane On A Microchip, Keith Male

Materials Engineering

A microfluidic device was synthesized out of polydimethyl siloxane (PDMS) to simulate the structure of the alveolar-capillary interface of the human lung. Soft lithography techniques were used to build a mold structure out of SU-8 epoxy at heights ranging from 30µm to 110 µm on a silicon substrate, with the 70 µm structure working the best. A mixture of 10:1 Sylgard 184 elastomer was then cast using the mold, and cured at a temperature of 80^oC. For the porous membrane, the PDMS was spun on at 6000rpm for 30 seconds using a spin coater to produce a membrane …

The Mitigation Of Eutrophication Using Microporous Polymer Membranes To Control Algae Growth, Christopher R. Riley

Materials Engineering

A system was designed to mitigate the accelerated process of anthropogenic eutrophication. This system aimed to contain Chlorella Vulgaris microalgae cells within an enclosed polymer membrane pouch while allowing for water and nutrients to diffuse through the pouch. As a test model, a 10 gallon aquarium was partitioned into three sections using polycarbonate membranes with 1 micron pore diameters. Each section was then gradually filled with a deionized water and Bristol solution recommended for microalgae growth. Phosphate and nitrate were added to Section A of the aquarium and allowed to diffuse throughout the tank. A water pump was used to …

Ros-Drill Automation: Visual Feedback Control And Rotational Motion Tracking, Jhon F. Diaz

Master's Theses

ICSI (intra-cytoplasmic sperm injection) has attracted research interest from both biological and engineering groups. The technology is constantly evolving to perform this procedure with precision and speed. One such development is the contribution of this thesis. We focus on a relatively recent procedure called Ros-Drill^© (rotationally oscillating drill), of which the early versions have already been effectively utilized for the mice. In the first part, we present a procedure to automate a critical part of the operation: initiation of the rotational oscillation, Visual feedback is used to track the pipette tip. Predetermined species-specific penetration depth is successfully utilized …

Designing A Membrane Module For Determining The Permeance Of High Fluxing Membranes And The Testing Rtil-Membranes For Dehumidification., Sikyun Bae

Electronic Theses and Dissertations

Membrane-based gas dehumidification can have technical energy, and economical advantages over other dehumidification technologies. Because, it is simple to install, ease to operate, and take low process cost. Removal of water vapor from gases constitutes a significant expenditure of energy in our society. Dehydration via a membrane process would constitute wide spread energy savings. This thesis explores experimental issues involved with testing Room Temperature Ionic Liquid(RTIL)-membrane for dehumidifying gases. RTIL-membranes or Supported Ionic Liquid Membranes (SILMs) have advantageous performance for the separations of the gas pair CO2/CH4 and CO2/N2. Previous research did not separate the membrane mass transport resistance the …

Bench-Scale Assessment Of Low Pressure Membrane Fouling: Characterization And Examination The Role Of Organic Nitrogen Compounds, Anh Hai Nguyen

Open Access Dissertations

The primary goal of this research was to improve understanding of the fouling of low pressure hollow fiber membranes used in drinking water treatment. The major difference of this study compared to other reported studies was the use of a hollow fiber membrane module at operating conditions mimicking those of full-scale practice. Two poly(vinylidene-fluoroethylene) based hollow fiber membranes (A and B) were tested. Different types of fouling indices (total, hydraulic irreversible, chemical irreversible) developed based on a resistance in series model were used to assess membrane performance. Data from bench-scale and full-scale plants were compared to validate the use of …

Design, Fabrication, Modeling And Characterization Of Electrostatically-Actuated Silicon Membranes, Brian C. Stahl

Master's Theses

This thesis covers the design, fabrication, modeling and characterization of electrostatically actuated silicon membranes, with applications to microelectromechanical systems (MEMS). A microfabrication process was designed to realize thin membranes etched into a silicon wafer using a wet anisotropic etching process. These flexible membranes were bonded to a rigid counterelectrode using a photo-patterned gap layer. The membranes were actuated electrostatically by applying a voltage bias across the electrode gap formed by the membrane and the counterelectrode, causing the membrane to deflect towards the counterelectrode. This deflection was characterized for a range of actuating voltages and these results were compared to the …

Synthesis And Characterization Of Macromolecular Layers Grafted To Polymer Surfaces, Oleksandr Burtovyy

All Dissertations

The composition and behavior of surfaces and interfaces play a pivotal role in dictating the overall efficiency of the majority of polymeric materials and devices. Surface properties of the materials can be altered using surface modification techniques. It is necessary to highlight that successful methods of surface modification should affect only the upper layer of the polymer material without changing bulk properties. The processes must introduce new functionalities to the surface, optimize surface roughness, lubrication, hydrophobicity, hydrophilicity, adhesion, conductivity, and/or biocompatibility.
Research presented in this dissertation is dedicated to the synthesis, characterization, and application of thin macromolecular layers anchored to …

Solvent Resistant Microporous/Nanoporous Polymeric Hollow Fiber And Flat Film Membranes And Their Applications, Praveen B. Kosaraju

Dissertations

The separation and purification of organic-solvent-based process streams may be carried out by membrane processes such as nanofiltration/ultrafiltration/microfiltration and membrane solvent extraction. Lack of solvent stability and chemical stability of most commercially available membranes is limiting the utilization of the above mentioned membrane technologies. This dissertation was primarily focused on developing solvent resistant hollow fiber and flat film membranes for separation and purification of organic-solvent-based process streams.

Available porous polymeric supports (Polypropylene (PP), Polyethersulfone (PES) and Nylon) suitable for the required solvent-stable applications were chosen first and then the supports were modified to satisfy the requirements for the applications. Membrane …

An Investigation Of Size Exclusion And Diffusion Controlled Membrane Fouling, Colin Michael Hobbs

Electronic Theses and Dissertations

The reduction of membrane productivity (i.e. membrane fouling) during operation occurs in virtually all membrane applications. Membrane fouling originates from the method by which membranes operate: contaminants are rejected by the membrane and retained on the feed side of the membrane while treated water passes through the membrane. The accumulation of these contaminants on the feed side of the membrane results in increased operating pressures, increased backwashing frequencies, increased chemical cleaning frequencies, and increased membrane replacement frequencies. The most significant practical implication of membrane fouling is increased operating and maintenance costs. As such, membrane fouling must be properly managed to …

Modeling Of Membrane Solute Mass Transfer In Ro/Nf Membrane Systems, Yu Zhao

Electronic Theses and Dissertations

Five articles describing the impact of surface characteristics, and development of mass transfer models for diffusion controlled membrane applications are published in this dissertation. Article 1 (Chapter 3) describes the impact of membrane surface characteristics and NOM on membrane performance for varying pretreatment and membranes during a field study. Surface charge, hydrophobicity and roughness varied significantly among the four membranes used in the study. Membrane surface characteristics, NOM and SUVA measurements were used to describe mass transfer in a low pressure RO integrated membrane system. Inorganic and organic solute and water mass transfer coefficients were systematically investigated for dependence on …