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Description
Calcium hydroxide carbonation processes were studied to investigate the potential for abiotic soil improvement. Different mixtures of common soil constituents such as sand, clay, and granite were mixed with a calcium hydroxide slurry and carbonated at approximately 860 psi. While the carbonation was successful and calcite formation was strong on sample exteriors, a 4 mm passivating boundary layer effect was observed, impeding the carbonation process at the center. XRD analysis was used to characterize the extent of carbonation, indicating extremely poor carbonation and therefore CO2 penetration inside the visible boundary. The depth of the passivating layer was found to be independent of both time and choice of aggregate. Less than adequate strength was developed in carbonated trials due to formation of small, weakly-connected crystals, shown with SEM analysis. Additional research, especially in situ analysis with thermogravimetric analysis would be useful to determine the causation of poor carbonation performance. This technology has great potential to substitute for certain Portland cement applications if these issues can be addressed.
ContributorsHermens, Stephen Edward (Author) / Bearat, Hamdallah (Thesis director) / Dai, Lenore (Committee member) / Mobasher, Barzin (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2015-05
Description
Ethanol is a widely used biofuel in the United States that is typically produced through the fermentation of biomass feedstocks. Demand for ethanol has grown significantly from 2000 to 2015 chiefly due to a desire to increase energy independence and reduce the emissions of greenhouse gases associated with transportation. As demand grows, new ethanol plants must be developed in order for supply to meet demand. This report covers some of the major considerations in developing these new plants such as the type of biomass used, feed treatment process, and product separation and investigates their effect on the economic viability and environmental benefits of the ethanol produced. The dry grind process for producing ethanol from corn, the most common method of production, is examined in greater detail. Analysis indicates that this process currently has the highest capacity for production and profitability but limited effect on greenhouse gas emissions compared to less common alternatives.
ContributorsSchrilla, John Paul (Author) / Kashiwagi, Dean (Thesis director) / Kashiwagi, Jacob (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2015-05
Description
Microbial fuel cells (MFCs) promote the sustainable conversion of organic matter in black water to electrical current, enabling the production of hydrogen peroxide (H2O2) while making waste water treatment energy neutral or positive. H2O2 is useful in remote locations such as U.S. military forward operating bases (FOBs) for on-site tertiary water treatment or as a medical disinfectant, among many other uses. Various carbon-based catalysts and binders for use at the cathode of a an MFC for H2O2 production are explored using linear sweep voltammetry (LSV) and rotating ring-disk electrode (RRDE) techniques. The oxygen reduction reaction (ORR) at the cathode has slow kinetics at conditions present in the MFC, making it important to find a catalyst type and loading which promote a 2e- (rather than 4e-) reaction to maximize H2O2 formation. Using LSV methods, I compared the cathodic overpotentials associated with graphite and Vulcan carbon catalysts as well as Nafion and AS-4 binders. Vulcan carbon catalyst with Nafion binder produced the lowest overpotentials of any binder/catalyst combinations. Additionally, I determined that pH control may be required at the cathode due to large potential losses caused by hydroxide (OH-) concentration gradients. Furthermore, RRDE tests indicate that Vulcan carbon catalyst with a Nafion binder has a higher H2O2 production efficiency at lower catalyst loadings, but the trade-off is a greater potential loss due to higher activation energy. Therefore, an intermediate catalyst loading of 0.5 mg/cm2 Vulcan carbon with Nafion binder is recommended for the final MFC design. The chosen catalyst, binder, and loading will maximize H2O2 production, optimize MFC performance, and minimize the need for additional energy input into the system.
ContributorsStadie, Mikaela Johanna (Author) / Torres, Cesar (Thesis director) / Popat, Sudeep (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2015-05
Description
Currently, approximately 40% of the world’s electricity is generated from coal and coal power plants are one of the major sources of greenhouse gases accounting for a third of all CO2 emissions. The Integrated Gasification Combined Cycle (IGCC) has been shown to provide an increase in plant efficiency compared to traditional coal-based power generation processes resulting in a reduction of greenhouse gas emissions. The goal of this project was to analyze the performance of a new SNDC ceramic-carbonate dual-phase membrane for CO2 separation. The chemical formula for the SNDC-carbonate membrane was Sm0.075Nd0.075Ce0.85O1.925. This project also focused on the use of this membrane for pre-combustion CO2 capture coupled with a water gas shift (WGS) reaction for a 1000 MW power plant. The addition of this membrane to the traditional IGCC process provides a purer H2 stream for combustion in the gas turbine and results in lower operating costs and increased efficiencies for the plant. At 900 °C the CO2 flux and permeance of the SNDC-carbonate membrane were 0.65 mL/cm2•min and 1.0×10-7 mol/m2•s•Pa, respectively. Detailed in this report are the following: background regarding CO2 separation membranes and IGCC power plants, SNDC tubular membrane preparation and characterization, IGCC with membrane reactor plant design, process heat and mass balance, and plant cost estimations.
ContributorsDunteman, Nicholas Powell (Author) / Lin, Jerry (Thesis director) / Dong, Xueliang (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor) / School of Sustainability (Contributor)
Created2014-05
Description
In this Honors thesis, direct flame solid oxide fuel cells (DFFC) were considered for their feasibility in providing a means of power generation for remote powering needs. Also considered for combined heat and fuel cell power cogeneration are thermoelectric cells (TEC). Among the major factors tested in this project for all cells were life time, thermal cycle/time based performance, and failure modes for cells. Two types of DFFC, anode and electrolyte supported, were used with two different fuel feed streams of propane/isobutene and ethanol. Several test configurations consisting of single cells, as well as stacked systems were tested to show how cell performed and degraded over time. All tests were run using a Biologic VMP3 potentiostat connected to a cell placed within the flame of a modified burner MSR® Wisperlite Universal stove. The maximum current and power output seen by any electrolyte supported DFFCs tested was 47.7 mA/cm2 and 9.6 mW/cm2 respectively, while that generated by anode supported DFFCs was 53.7 mA/cm2 and 9.25 mW/cm2 respectively with both cells operating under propane/isobutene fuel feed streams. All TECs tested dramatically outperformed both constructions of DFFC with a maximum current and power output of 309 mA/cm2 and 80 mW/cm2 respectively. It was also found that electrolyte supported DFFCs appeared to be less susceptible to degradation of the cell microstructure over time but more prone to cracking, while anode supported DFFCs were dramatically less susceptible to cracking but exhibited substantial microstructure degradation and shorter usable lifecycles. TECs tested were found to only be susceptible to overheating, and thus were suggested for use with electrolyte supported DFFCs in remote powering applications.
ContributorsTropsa, Sean Michael (Author) / Torres, Cesar (Thesis director) / Popat, Sudeep (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2014-05
Description
Plastics continue to benefit society in innumerable ways, even though recent public focus on plastics has centered mostly on human health and environmental concerns, including their endocrine-disrupting properties and the long-term pollution they represent. The benefits of plastics are particularly apparent in medicine and public health. Plastics are versatile, cost-effective, require less energy to produce than alternative materials like metal or glass, and can be manufactured to have many different properties. Due to these characteristics, polymers are used in diverse health applications like disposable syringes and intravenous bags, sterile packaging for medical instruments as well as in joint replacements, tissue engineering, etc. However, not all current uses of plastics are prudent and sustainable, as illustrated by the widespread, unwanted human exposure to endocrine-disrupting bisphenol A (BPA) and di-(2-ethylhexyl) phthalate (DEHP), problems arising from the large quantities of plastic being disposed of, and depletion of non-renewable petroleum resources as a result of the ever-increasing mass production of plastic consumer articles. Using the health-care sector as example, this review concentrates on the benefits and downsides of plastics and identifies opportunities to change the composition and disposal practices of these invaluable polymers for a more sustainable future consumption. It highlights ongoing efforts to phase out DEHP and BPA in the health-care and food industry and discusses biodegradable options for plastic packaging, opportunities for reducing plastic medical waste, and recycling in medical facilities in the quest to reap a maximum of benefits from polymers without compromising human health or the environment in the process.
ContributorsNorth, Emily Jean (Co-author) / Halden, Rolf (Co-author, Thesis director) / Mikhail, Chester (Committee member) / Hurlbut, Ben (Committee member) / Barrett, The Honors College (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / Chemical Engineering Program (Contributor)
Created2013-05
Description
Lignin is a naturally abundant source of aromatic carbon but is largely underutilized in industry because it is difficult to decompose. Under the current study we engineered Corynebacterium glutamicum for the depolymerization of lignin with the goal of using it as raw feed for the sustainable production of valuable chemicals. C. glutamicum is a standout candidate for the depolymerization and assimilation of lignin because of its performance as an industrial producer of amino acids, resistance to aromatic compounds in lignin, and low extracellular protease activity. Three different foreign and native ligninolytic enzymes were tested in combination with three signal peptides to assess lignin degradation efficacy. At this stage, six of the nine plasmid constructs have been constructed.
ContributorsEllis, Dylan Scott (Author) / Varman, Arul Mozhy (Thesis director) / Nannenga, Brent (Committee member) / Nowroozi, Farnaz (Committee member) / Chemical Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description
As Energy needs grow and photovoltaics expand to meet humanity’s demand for electricity, waste modules will start building up. Tao et. al. propose a recycling process to recover all precious solar cell materials, a process estimated to generate a potential $15 billion in revenue by 2050. A key part of this process is metal recovery, and specifically, silver recovery. Silver recovery via electrowinning was studied using a hydrofluoric acid leachate/electrolyte. Bulk electrolysis trials were performed at varied voltages using a silver working electrode, silver pseudo-reference electrode and a graphite counter-electrode. The highest mass recovery achieved was 98.8% which occurred at 0.65 volts. Product purity was below 90% for all trials and coulombic efficiency never reached above 20%. The average energy consumption per gram of reduced silver was 2.16kWh/kg. Bulk electrolysis indicates that parasitic reactions are drawing power from the potentiostat and limiting the mass recovery of the system. In order to develop this process to the practical use stage, parasitic reactions must be eliminated, and product purity and power efficiency must improve. The system should be run in a vacuum environment and the reduction peaks in the cell should be characterized using cyclic voltammetry.
ContributorsTezak, Cooper R (Author) / Tao, Meng (Thesis director) / Phelan, Patrick (Committee member) / Chemical Engineering Program (Contributor) / School of International Letters and Cultures (Contributor) / Barrett, The Honors College (Contributor)
Created2020-12
Description
The algal fuel industry has existed since the 1980s without fully commercializing a product. Algal fuels are potentially viable replacements for fossil fuels due to their fast cultivation, high oil content, carbon dioxide sequestration during growth, and ability to be grown on non-arable land. For this thesis, six companies from 61 investigated were interviewed about their history with biofuels, technological changes they have gone through, and views for the future of the industry. All companies interviewed have moved away from fuel production largely due to high production costs and have moved primarily toward pharmaceuticals and animal feed production as well as wastewater treatment. While most do not plan to return to the biofuel industry in the near future, a return would likely require additional legislation, increased technological innovation, and coproduction of multiple products.
ContributorsMassey, Alexandria Rae (Author) / Parker, Nathan (Thesis director) / Agusdinata, Buyung (Committee member) / Chemical Engineering Program (Contributor, Contributor) / School of Sustainability (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Due to the wide range of health properties flavonoids possess, flavonoids are sold in health supplements to the general public. Flavonoids are also utilized in research but have a high cost due to current production techniques. This project focuses on engineering two DNA recombinants to develop new strains of Corynebacterium glutamicum that can produce flavonoids pinocembrin and naringenin. After culturing Escherichia coli colonies containing genes of interest, the genes were collected and purified by PCR reactions. The recombinant plasmid was assembled using CPEC and successfully transformed into Escherichia coli, with plans to transform Corynebacterium glutamicum to experiment and determine which recombinant can produce more pinocembrin and naringenin. Design work for other DNA recombinants, which were not the focus of this project, was also completed.
ContributorsWong, Adam (Co-author, Co-author) / Varman, Arul Mozhy (Thesis director) / Nielsen, David (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05