Matching Items (14)
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- All Subjects: Electrospinning
- All Subjects: Water
- Creators: Chemical Engineering Program
Description
The impact of physical/chemical properties of gray water on microbial inactivation in gray water using chlorine was investigated through creating artificial gray water in lab, varying specific components, and then measuring microbial inactivation. Gray water was made through taking autoclaved nanopure water, and increasing the concentration of surfacants, the turbidity, the concentration of organic content, and spiking E. coli grown in tryptic soy broth (TSB); chlorine was introduced using Clorox Disinfecting Bleach2. Bacteria was detected using tryptic soy agar (TSA), and E. coli was specifically detected using the selective media, brilliance. The log inactivation of bacteria detected using TSA was shown to be inversely related to the turbidity of the solution. Complete inactivation of E. coli concentrations between 104-105 CFU/100 ml in gray water with turbidities between 10-100 NTU, 0.1-0.5 mg/L of humic acid, and 0.1 ml of Dawn Ultra, was shown to occur, as detected by brilliance, at chlorine concentrations of 1-2 mg/L within 30 seconds. These result in concentration time (CT) values between 0.5-1 mg/L·min. Under the same gray water conditions, and an E. coli concentration of 104 CFU/100 ml and a chlorine concentration of 0.01 mg/L, complete inactivation was shown to occur in all trials within two minutes. These result in CT values ranging from 0.005 to 0.02. The turbidity and humic acid concentration were shown to be inversely related to the log inactivation and directly related to the CT value. This study shows that chlorination is a valid method of treatment of gray water for certain irrigation reuses.
ContributorsGreenberg, Samuel Gabe (Author) / Abbaszadegan, Morteza (Thesis director) / Schoepf, Jared (Committee member) / Alum, Absar (Committee member) / Chemical Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
Currently in synthetic biology only the Las, Lux, and Rhl quorum sensing pathways have been adapted for broad engineering use. Quorum sensing allows a means of cell to cell communication in which a designated sender cell produces quorum sensing molecules that modify gene expression of a designated receiver cell. While useful, these three quorum sensing pathways exhibit a nontrivial level of crosstalk, hindering robust engineering and leading to unexpected effects in a given design. To address the lack of orthogonality among these three quorum sensing pathways, previous scientists have attempted to perform directed evolution on components of the quorum sensing pathway. While a powerful tool, directed evolution is limited by the subspace that is defined by the protein. For this reason, we take an evolutionary biology approach to identify new orthogonal quorum sensing networks and test these networks for cross-talk with currently-used networks. By charting characteristics of acyl homoserine lactone (AHL) molecules used across quorum sensing pathways in nature, we have identified favorable candidate pathways likely to display orthogonality. These include Aub, Bja, Bra, Cer, Esa, Las, Lux, Rhl, Rpa, and Sin, which we have begun constructing and testing. Our synthetic circuits express GFP in response to a quorum sensing molecule, allowing quantitative measurement of orthogonality between pairs. By determining orthogonal quorum sensing pairs, we hope to identify and adapt novel quorum sensing pathways for robust use in higher-order genetic circuits.
ContributorsMuller, Ryan (Author) / Haynes, Karmella (Thesis director) / Wang, Xiao (Committee member) / Barrett, The Honors College (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / Department of Chemistry and Biochemistry (Contributor) / School of Life Sciences (Contributor)
Created2015-05
Description
One of the primary bottlenecks to chemical production in biological organisms is the toxicity of the chemical. Overexpression of efflux pumps has been shown to increase tolerance to aromatic compounds such as styrene and styrene oxide. Tight control of pump expression is necessary to maximize titers and prevent excessive strain on the cells. This study aimed to identify aromatic-sensitive native promoters and heterologous biosensors for construction of closed-loop control of efflux pump expression in E. coli. Using a promoter library constructed by Zaslaver et al., activation was measured through GFP output. Promoters were evaluated for their sensitivity to the addition of one of four aromatic compounds, their "leaking" of signal, and their induction threshold. Out of 43 targeted promoters, 4 promoters (cmr, mdtG, yahN, yajR) for styrene oxide, 2 promoters (mdtG, yahN) for styrene, 0 promoters for 2-phenylethanol, and 1 promoter for phenol (pheP) were identified as ideal control elements in aromatic bioproduction. In addition, a series of three biosensors (NahR, XylS, DmpR) known to be inducible by other aromatics were screened against styrene oxide, 2-phenylethanol, and phenol. The targeted application of these biosensors is aromatic-induced activation of linked efflux pumps. All three biosensors responded strongly in the presence of styrene oxide and 2-phenylethanol, with minor activation in the presence of phenol. Bioproduction of aromatics continues to gain traction in the biotechnology industry, and the continued discovery of aromatic-inducible elements will be essential to effective pathway control.
ContributorsXu, Jimmy (Author) / Nielsen, David (Thesis director) / Wang, Xuan (Committee member) / School of Life Sciences (Contributor) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
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 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.
ContributorsShabilla, Andrew Daniel (Author) / Lind, Mary Laura (Thesis director) / Lin, Jerry (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2014-05
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. 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.
ContributorsPiper, Jessica Marie (Author) / Lind, Mary Laura (Thesis director) / Montoya-Gonzales, Roxanna (Committee member) / Barrett, The Honors College (Contributor) / School of Sustainability (Contributor) / Chemical Engineering Program (Contributor)
Created2014-05
Description
The objective of this research is to create biodegradable mats with tunable characteristics such as fiber diameter and surface area. The drug delivery mats enable spatially controlled delivery of disease-specific therapeutics. Using a large electric potential to draw fibers from a solution flowing at a specific rate, the polymer fibers reach a grounded target several inches away. The biodegradable polymer used in this study was poly(lactic acid-co-glycolic acid) (PLGA). PLGA solutions ranging from 0.5 to 27 wt.% were prepared by dissolving the block copolymer in a solvent mixture containing tetrahydrofuran (THF) and dimethylformamide (DMF) at a 3:1 weight ratio. They were then electrospun at needle-to-target distances of 7, 14, and 18 cm and rates ranging from 0.8 to 4 mL/h. The range of voltage used was between 8 – 15 kV, which was based on the observation of the formation of a Taylor cone, largely affected by on the environment and weather (e.g., temperature and humidity in the lab). A 27 wt.% PLGA solution, electrospun at 1 mL/h at a voltage of 11.25 kV and needle-to-target distance of 14 cm produced uniform fibers with an average fiber diameter of 0.985 m. All other parameters outside the range given created beaded fibers. In addition, solution rheology was performed on some of the PLGA solution to measure viscosity, which is directly correlated to the fiber diameter of the electrospun mats. Observing the impact of solvent on fiber spinning and fiber diameter brings about many positive results in developing fully characterized and well-understood fibrous mats for drug delivery. The nanoscale fibers will be used as drug delivery mats and, therefore, the biodegradation kinetics of the polymers will be studied. Next, parameters of the polymers as well as the polymeric mats will be correlated to the degradation-mediated release of small molecule therapeutics (e.g., peptides, drugs, etc.) such that time-resolved dosing profiles can be created.
ContributorsLent, Madeline (Author) / Green, Matthew (Thesis director) / Holloway, Julianne (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
p-Coumaric acid is used in the food, pharmaceutical, and cosmetic industries due to its versatile properties. While prevalent in nature, harvesting the compound from natural sources is inefficient, requiring large quantities of producing crops and numerous extraction and purification steps. Thus, the large-scale production of the compound is both difficult and costly. This research aims to produce p-coumarate directly from renewable and sustainable glucose using a co-culture of Yeast and E. Coli. Methods used in this study include: designing optimal media for mixed-species microbial growth, genetically engineering both strains to build the production pathway with maximum yield, and analyzing the presence of p-Coumarate and its pathway intermediates using High Performance Liquid Chromatography (HPLC). To date, the results of this project include successful integration of C4H activity into the yeast strain BY4741 ∆FDC1, yielding a strain that completely consumed trans-cinnamate (initial concentration of 50 mg/L) and produced ~56 mg/L p-coumarate, a resting cell assay of the co-culture that produced 0.23 mM p-coumarate from an initial L-Phenylalanine concentration of 1.14 mM, and toxicity tests that confirmed the toxicity of trans-cinnamate to yeast for concentrations above ~50 mg/L. The hope for this project is to create a feasible method for producing p-Coumarate sustainably.
ContributorsJohnson, Kaleigh Lynnae (Author) / Nielsen, David (Thesis director) / Thompson, Brian (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
Obtaining access to clean water is a global problem that is becoming more important with increasing population and advancing technology. Desalination through reverse osmosis (RO) is a promising technology takes advantage of the global supply of saline water to augment its limited freshwater reservoirs. To increase RO membrane performance, the feedwater is pretreated to take any excess pollutants out before the desalination. These pretreatment membranes are susceptible to fouling, which reduces efficiency and drives up costs of the overall process. Increasing the hydrophilicity of these membranes would reduce fouling, and electrospinning is a production method of pretreatment membranes with the capability to control hydrophilicity. This work explores how the composition of electrospun fibrous membranes containing blends of hydrophilic and hydrophobic polymers affects membrane characteristics such as wettability as well as filtration performance. Nonwoven, nanoscale membranes were prepared using electrospinning with a targeted application of pretreatment in water filtration. Using a rotating collector, electrospun mats of hydrophobic poly(vinyl chloride) (PVC) and hydrophilic poly(vinyl alcohol) (PVA) were simultaneously deposited from separate polymer solutions, and their polymer compositions were then characterized using Fourier Transform Infrared (FTIR) spectra. The data did not reveal a reliable correlation established between experimental control variables like flow rate and membrane composition. However, when the membranes' hydrophilicity was analyzed using static water contact angle measurements, a trend between PVA content and hydrophilicity was seen. This shows that the hypothesis of increasing PVA content to increase hydrophilicity is reliable, but with the current experimental design the PVA content is not controllable. Therefore, the primary future work is making a new experimental setup that will be able to better control membrane composition. Filtration studies to test for fouling and size exclusion will be performed once this control is obtained.
ContributorsTronstad, Zachary (Author) / Green, Matthew (Thesis director) / Holloway, Julianne (Committee member) / Epps, Thomas (Committee member) / Chemical Engineering Program (Contributor) / Materials Science and Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-12
Description
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.
ContributorsDurbin, Mitchell (Co-author) / Rivers, Frederick (Co-author) / Lind Thomas, MaryLaura (Thesis director) / Durgan, Pinar Cay (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
The following thesis documents a two-fold approach to investigate challenges pertaining to water purification, first through a meta-analysis of ionic liquid toxicity, then through experimentation aimed at developing water pre-treatment membranes. Ionic liquids (ILs) are salts with low melting points, typically liquid at room temperature. Several extraordinary physical attributes, e.g. low viscosity, high conductivity, low to no vapor pressure, etc., and seemingly unlimited combinations available, have pushed IL research to the forefront of many research fronts. Concerns are raised as ionic liquids are rushed into commercial production without sufficient environmental regulation. Research has shown that the chemicals are in fact toxic, yet have developed a reputation for being “green” chemicals due to select physical attributes and applications. The meta-analysis discussed focuses on industry perception of ionic liquid toxicity through a patent review, and considers toxicity of ILs comparatively against other chemical families with well-established toxicity. The meta-analysis revealed that the total patent literature pertaining to ILs (n=3358) resulted in 112 patents that addressed the toxicity of ILs, and notably few (n=17) patents defined ILs as toxic, representing only 0.51% of the evaluated body of work on intellectual property claims. Additionally, toxicity of ionic liquids is comparable to that of other chemical families.
The objective of the experimentation was to explore the effect of crosslinker chain length on the morphology of nanofiber mats. Specifically, poly(vinyl alcohol (PVA) was electrospun into nanofiber mats and poly(ethylene) glycol bis(carboxylic acid) (PEG diacid) was used as the crosslinking agent. As-spun fibers had average fiber diameter of 70 ± 30 nm with an average pore size of 0.10 ± 0.16 μm^2. The fiber diameter for the mats crosslinked with the shorter PEG diacid (Mn = 250) increased to 110 ± 40 nm with an average pore size of 0.11 ± 0.04 μm^2. The mats crosslinked with the longer PEG diacid (Mn = 600) had fiber diameters of 180 ± 10 nm with an average pore size 0.01 ± 0.02 μm^2.
The objective of the experimentation was to explore the effect of crosslinker chain length on the morphology of nanofiber mats. Specifically, poly(vinyl alcohol (PVA) was electrospun into nanofiber mats and poly(ethylene) glycol bis(carboxylic acid) (PEG diacid) was used as the crosslinking agent. As-spun fibers had average fiber diameter of 70 ± 30 nm with an average pore size of 0.10 ± 0.16 μm^2. The fiber diameter for the mats crosslinked with the shorter PEG diacid (Mn = 250) increased to 110 ± 40 nm with an average pore size of 0.11 ± 0.04 μm^2. The mats crosslinked with the longer PEG diacid (Mn = 600) had fiber diameters of 180 ± 10 nm with an average pore size 0.01 ± 0.02 μm^2.
ContributorsRomero, Felicia Navidad (Author) / Green, Matthew D. (Thesis director) / Lind, Mary Laura (Committee member) / Long, Timothy E. (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05