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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

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.
ContributorsKing, Julia Ann (Author) / Lind, Mary Laura (Thesis director) / Durgun, Pinar Cay (Committee member) / Chemical Engineering Program (Contributor) / Materials Science and Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
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The ability to sense applied damage and correlate it with a measurable signal is extremely desirable in any material application to prevent catastrophic failure and the possible loss of use of the material or human injury. Mechanochemistry, in which mechanical forces induce chemical changes, can allow for targeted damage detection

The ability to sense applied damage and correlate it with a measurable signal is extremely desirable in any material application to prevent catastrophic failure and the possible loss of use of the material or human injury. Mechanochemistry, in which mechanical forces induce chemical changes, can allow for targeted damage detection by way of embedded mechanophore units, with certain mechanophore chemistries emitting a fluorescent signal in response an applied force. In this work, we successfully employed microparticles of the mechanophore dimeric 9-anthracene carboxylic acid (Di-AC) in a thermoset polyurethane matrix to study their application as universal stress-sensing fillers in network polymer matrix composites. Under a compressive force, there is bond breakage in the mechanically weak cyclooctane photodimers of Di-AC, such that there is reversion to the fluorescent anthracene-type monomers. This fluorescent emission was then correlated to the applied strain, and the precursors to damage were detected with a noticeable fluorescent signal change at an applied strain of only 2%. This early damage detection was additionally possible at very low particle loadings of 2.5 and 5 wt%, with the 5 wt% loading showing enhanced material properties compared to the 2.5 wt%, due to particle reinforcement in the composite. Overall, the synthesis of Di-AC as a stress-sensitive particle filler allows for facile addition of advanced functionality to these ubiquitous thermoset composites.
ContributorsDasgupta, Avi Ryan (Author) / Dai, Lenore (Thesis director) / Nofen, Elizabeth (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
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Alternative ion exchange membranes for implementation in a peroxide production microbial electrochemical cel (PP-MEC) are explored through membrane stability tests with NaCl electrolyte and stabilizer EDTA at varying operational pHs. PP-MEC performance parameters \u2014 H2O2 concentration, current density, coulombic efficiency and power input required \u2014 are optimized over a 7

Alternative ion exchange membranes for implementation in a peroxide production microbial electrochemical cel (PP-MEC) are explored through membrane stability tests with NaCl electrolyte and stabilizer EDTA at varying operational pHs. PP-MEC performance parameters \u2014 H2O2 concentration, current density, coulombic efficiency and power input required \u2014 are optimized over a 7 month continuous operation period based on their response to changes in HRT, EDTA concentration, air flow rate and electrolyte. I found that EDTA was compatible for use with the membranes. I also determined that AMI membranes were preferable to CMI and FAA because it was consistently stable and maintained its structural integrity. Still, I suggest testing more membranes because the AMI degraded in continuous operation. The PP-MEC produced up to 0.38 wt% H2O2, enough to perform water treatment through the Fenton process and significantly greater than the 0.13 wt% batch PP-MEC tests by previous researchers. It ran at > 0.20 W-hr/g H2O2 power input, ~ three orders of magnitude less than what is required for the anthraquinone process. I recommend high HRT and EDTA concentration while running the PP- MEC to increase H2O2 concentration, but low HRT and low EDTA concentration to decrease power input required. I recommend NaCl electrolyte but suggest testing new electrolytes that may control pH without degrading H2O2. I determined that air flow rate has no effect on PP-MEC operation. These recommendations should optimize PP-MEC operation based on its application.
ContributorsChowdhury, Nadratun Naeem (Author) / Torres, Cesar (Thesis director) / Popat, Sudeep (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description

This thesis discusses the yield analysis process for determining the efficacy of experimental changes to a semiconductor manufacturing line, specifically within the chemical mechanical planarization department. Three yield analysis projects were analyzed and related to relevant literature to determine how the changes might impact overall semiconductor yield.

ContributorsRichards, Andrew (Author) / Machas, Michael (Thesis director) / Maguregui, Edgar (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2023-05
Description

Plastic consumption has reached astronomical amounts. The issue is the single-use plastics that continue to harm the environment, degrading into microplastics that find their way into our environment. Finding sustainable, reliable, and safe methods to break down plastics is a complex but valuable endeavor. This research aims to assess the

Plastic consumption has reached astronomical amounts. The issue is the single-use plastics that continue to harm the environment, degrading into microplastics that find their way into our environment. Finding sustainable, reliable, and safe methods to break down plastics is a complex but valuable endeavor. This research aims to assess the viability of using biochar as a catalyst to break down polyethylene terephthalate (PET) plastics under hydrothermal liquefaction conditions. PET is most commonly found in single-use plastic water bottles. Using glycolysis as the reaction, biochar is added and assessed based on yield and time duration of the reaction. This research suggests that temperatures of 300℃ and relatively short experimental times were enough to see the complete conversion of PET through glycolysis. Further research is necessary to determine the effectiveness of biochar as a catalyst and the potential of process industrialization to begin reducing plastic overflow.

ContributorsWyatt, Olivia (Author) / Deng, Shuguang (Thesis director) / Jin, Kailong (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2023-05
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Membrane-based technology for gas separations is currently at an emerging stage of advancement and adoption for environmental and industrial applications due to its substantial advantages like lower energy and operating costs over the conventional gas separation technologies. Unfortunately, the available polymeric (or organic) membranes suffer a trade-off between permeance and

Membrane-based technology for gas separations is currently at an emerging stage of advancement and adoption for environmental and industrial applications due to its substantial advantages like lower energy and operating costs over the conventional gas separation technologies. Unfortunately, the available polymeric (or organic) membranes suffer a trade-off between permeance and selectivity. Mixed matrix membranes (MMMs) containing two-dimensional (2D) metal-organic frameworks (MOFs) as fillers are a highly sought approach to redress this trade-off given their enhanced gas permeabilities and selectivities compared to the pure polymeric membrane. These MMMs are increasingly gaining attention by researchers due to their unique properties and wide small- and large-scale gas separation applications. However, straightforward and scalable methods for the synthesis of MOFs nanosheets have thus far been persistently elusive. This study reports the single-phase preparation, and characterization of MMMs with 2D MOFs nanosheets as fillers. The prepared MOF and the polymer matrix form the ‘dense’ MMMs which exhibit increased gas diffusion resistance, and thus improved separation abilities. The single-phase approach was more successful than the bi-phase at synthesizing the MOFs. The influence of sonication power and time on the characteristics and performance of the membranes are examined and discussed. Increasing the sonication power from 50% to 100% reduces the pore size. Additionally, the ultimate effect on the selectivity and permeance of the MMMs with different single gases is reported. Analysis of results with various gas mixers indicates further performance improvements in these MMMs could be achieved by increasing sonication time and tuning suitable membrane thicknesses. Reported results reveal that MMMs are excellent candidates for next-generation gas mixture separations, with potential applications in CO2 capture and storage, hydrogen recovery, alkene recovery from alkanes, and natural gas purification.
ContributorsNkuutu, John (Author) / Mu, Bin (Thesis director) / Shan, Bohan (Committee member) / Chemical Engineering Program (Contributor) / School of Sustainability (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
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Improvement in carbon capture percentage was calculated as most effective in 10 mg/L-MEA BG-11 media, with improvement in carbon capture of 1.012% over the control. In studying the effect of agitation at 150 revolutions-per-minute (RPM) with a magnetic stir bar, it was found that mass transfer actually decreased. Future investigations

Improvement in carbon capture percentage was calculated as most effective in 10 mg/L-MEA BG-11 media, with improvement in carbon capture of 1.012% over the control. In studying the effect of agitation at 150 revolutions-per-minute (RPM) with a magnetic stir bar, it was found that mass transfer actually decreased. Future investigations are warranted to fully characterize the effect of different alkanolamine types, concentrations, and mixing regimens on mass transfer of CO2. In this thesis, emphasis was placed on experimental setup to allow for a discussion of the unexpected characteristics of the findings of the mass transfer experiments. Understanding the effect of experimental setup on mass transfer will be important in designing more effective methods of CO2 absorption for improving growth of cyanobacteria.
ContributorsMcallister, Cameron William (Author) / Nielsen, David (Thesis director) / Nannenga, Brent (Committee member) / School of Sustainability (Contributor) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
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Description
Engineering has historically been dominated by White men. However, in modern history, engineering is becoming more diverse as the opportunity to pursue engineering has become accessible to people of all races and genders. Yet, college ready high school students from nontraditional backgrounds—women, ethnic minorities, first-generation-to-college students, and those with financial

Engineering has historically been dominated by White men. However, in modern history, engineering is becoming more diverse as the opportunity to pursue engineering has become accessible to people of all races and genders. Yet, college ready high school students from nontraditional backgrounds—women, ethnic minorities, first-generation-to-college students, and those with financial need—often lack exposure to engineering, thus reducing their likelihood to pursue a career in this field. To create engineering learning experiences that can be expanded to a traditional high school science classroom, the Young Engineers Shape the World program at Arizona State University was consulted. The Young Engineers Shape the World program encourages women, notably the most underrepresented group in the engineering field, as well as other students of diverse backgrounds, to pursue engineering. The goal of this effort was to create a 3-contact hour chemical engineering based learning experience to help students in grades 10-11 learn about an application of chemical engineering. Using knowledge of chemical engineering, a soil pH testing activity was created, simulating a typical high school chemistry science experiment. In addition to measuring pH, students were asked to build a modern garden that contained a physical barrier that could protect the garden from acid rain while still allowing sunlight to reach the plant. Student feedback was collected in the form of an experience evaluation survey after each experience. Students found that the soil-moisture quality testing and design of a protective barrier was engaging. However, an iterative curriculum redesign-implement-evaluate effort is needed to arrive at a robust chemical engineering based design learning experience.
ContributorsOtis, Timothy Kevin (Author) / Ganesh, Tirupalavanam (Thesis director) / Schoepf, Jared (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
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Description
When it comes to the topic of chemical engineering, the general public has a set of neutral, if slightly uninformed perceptions that are largely tempered by the initial emotional responses to the field and its associated topics. These topics include the differentiation between chemical engineers and chemists, the importance and

When it comes to the topic of chemical engineering, the general public has a set of neutral, if slightly uninformed perceptions that are largely tempered by the initial emotional responses to the field and its associated topics. These topics include the differentiation between chemical engineers and chemists, the importance and potential danger of the products they produce, as well as the association of the subject matter with less than favorable secondary education experiences. This thesis consists of first assessing the opinions of a population meant to represent the general public regarding these subjects, then exploring the potential improvements of opinion and understanding that may be yielded from presenting the subject matter by way of a concise learning tool, such as a video. The results of this effort showed that factual understanding can be at least incrementally improved for 18% of participants through this method, while the effect on opinions can range from being improved to maintaining an enduring indifference, with an average of 17% of participants seeing improvement. Further iteration of this methodology with more consistent, impartial survey methods and refined questions could potentially yield more noteworthy improvements within the subjective domain, with the resultant learning tool of that iteration being applicable as not only an instrument of educating the general public, but also as a means to recruit potential students to the ASU chemical engineering degree program.
ContributorsJanovsky, Trey Patrick (Author) / Taylor, David (Thesis director) / Martin, Thomas (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
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Esters are important solvents in multiple industries including adhesives, food, and pharmaceuticals. Although esters are biodegradable solvents, the conventional process of producing them is not eco-friendly because they are largely derived from petrochemicals. This has led scientists to consider implementing biological routes in their production process by incorporating heterologous or

Esters are important solvents in multiple industries including adhesives, food, and pharmaceuticals. Although esters are biodegradable solvents, the conventional process of producing them is not eco-friendly because they are largely derived from petrochemicals. This has led scientists to consider implementing biological routes in their production process by incorporating heterologous or improving inherent esterification pathways. However, due to inequality in the biosynthesis of esters and their precursors (organic acid and alcohol), a significant amount of precursors are left unconverted, thereby lowering overall esterification efficiency. Therefore, the primary goal of the current research is to improve the ester titers by incorporating one more step of in vitro esterification with the culture broth, thereby esterifying the unconverted precursors using high efficiency commercial enzymes in the presence of compatible organic solvent. In principle, the medium containing the precursors will be treated with the enzyme in presence of organic solvent, where the precursors will be distributed in both the phases, aqueous and organic, based on their polarity, and the enzymatic esterification will happen at the interface. Hence, as a first step, efforts were made to optimize the reaction conditions, beginning with choosing the most efficient organic solvent and corresponding enzyme candidate. Our results showed that, for production of ethyl acetate through this reactive extraction approach, Novozyme435 exhibited significant esterification with chloroform, with almost 85% conversion efficiency. Further optimizations with phase ratios, pH and incubation time showed that the pH 6.0 (3.1 g/L) was the most optimum where ethyl acetate titer was found to improve 10 times than that at pH 7.0 (0.164 g/L) with the phase ratio of 1:1. The kinetic studies further added that the incubation at 37oC gives the maximum ethyl acetate production within 8h. After initial optimization studies, cell broth from E. coli cells transformed to overproduce an esterase was also tested with the reactive extraction method. It was found that there was a ~7.5X decrease in ethyl acetate production in the cell media versus synthetic samples with the same concentration of reactants. Such a large decrease indicates that enzymatic promiscuity or inhibition currently prevent the cell samples from reaching the same conversion as synthetic studies. To characterize the maximum reaction rate (Vmax) and affinity constants of the substrates to Novozym 435, further kinetic studies were performed with one minute of reaction. The mathematical model employed assumes that enzyme kinetics rather than diffusion was the rate limiting step, that the concentrations of reactants at the interface are equivalent to the initial concentration of reactants, and that neither substrate is an inhibitor. Vmax was found to be 18.5 Mmol min-1g-1 (of catalyst used), and the affinity constants were 0.957 M and 0.00557 M for acetic acid and ethanol respectively. Vmax was similar to literature values with Novozym 435, and the affinity constants indicate a much higher binding efficiency of ethanol in comparison to acetic acid, indicating that a cocktail of esters are likely produced from Novozym 435 in cell broth. Overall, moving away from fossil-fuel dependence is necessary to promote sustainable industry standards, and microbial cell factories combined with reactive extraction, if optimized for industrial applications, can replace harmful environmental procedures. By optimizing the reactive extraction process for ester production, biorefineries could become more competitive and economically feasible for numerous applications.

ContributorsKartchner, Danika (Author) / Varman, Arul Mozhy (Thesis director) / Nielsen, David (Committee member) / Soundappan, Thiagarajan (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor) / Watts College of Public Service & Community Solut (Contributor)
Created2022-05