Advisor: Dr. Fatih Dogan
Date & Time: Wednesday, October 20, 2021 at 3:00 PM
Location (Zoom): https://umsystem.zoom.us/j/96232558045
Abstract: Lead-acid batteries are an established technology with nearly 99% recyclability; however, capacity and cycle life are limiting factors compared to other battery chemistries. Lead-acid batteries produce only 40% of their theoretical capacity due to poor active mass utilization and PbSO4 pore blockage. The longevity of the batteries is hampered by secondary reactions during the cycle life such as corrosion and gassing.
The first focus area for this research is a reduction in the secondary reactions detrimental to the longevity and capacity of the lead-acid battery. To mitigate this issue, the thermodynamics and chemical reactions of a commercial electrolyte replacement called TydrolyteTM were investigated using a model smooth lead system. The electrolyte has a concentrated Eigen proton structure (H9O4+) that consists of a hydronium cation (H3O+) hydrated by three water molecules. For these studies, potentiodynamic sweeps and cyclic voltammetry techniques were used in the entire potential region where the positive (PbO2/PbSO4) and negative (Pb/PbSO4) plates of the battery operate. The effects of 1.265 g·mL-1 TydrolyteTM solution on the capacity-bearing reactions, rates of oxygen evolution, lead corrosion, and hydrogen evolution processes were evaluated and compared to the standard battery electrolyte.
The second area of research focused on positive active mass (PAM) utilization. The PAM utilization is of great importance, because it limits the theoretical capacity of the battery. The phsico-chemical properties of various graphite additives were incorporated into the positive paste, in a range of amounts, to study and compare their effects on PAM utilization. Several types of graphite differing in shape, size, type (expanded vs. not expanded), and thicknesses were incorporated into the positive paste. These differentiated graphite powder characteristics were correlated with the effects on discharge utilization at a wide range of current rates. Another approach involved direct mechanical modifications of the plate. By incorporating controlled porosity with specific pore volume, shape, size, and distribution into the positive plate, the pore structure was optimized to utilize the PAM more effectively. This study develops a method to build the porosity and elucidates the key pore structure parameters necessary to increase the capacity and cycle life of the battery.
Finally, process optimizations were explored to improve manufacturing of battery pastes and battery performance. Due to its rheological properties, positive lead-acid battery paste can be difficult to spread on lead current collectors accurately and efficiently in industry settings. A sodium polymethacrylate dispersant was studied as an effective positive paste additive that could lower the yield stress of the paste without affecting paste density and battery performance.
The limiting capacity and cycle life performances of lead-acid batteries were investigated and improved through several different approaches: an alternative electrolyte to mitigate secondary reactions, graphite additives to improve PAM utilization, and dispersant additives to help the industrial pasting process.
Advisor: Dr. Muthanna Al Dahhan
Date & Time: Thursday, October 21, 2021 at 3:00 PM
Location (Zoom): https://zoom.us/j/91255969020?pwd=U2lhZ0tnTllqTDlvaXBNeE40UVl1QT09
Abstract: It is an uphill battle to extract pollutants such as heavy metals, hydrocarbons, and radioactive metals from water and industrial wastewater. Emulsion liquid membrane (ELM) is an emerging technology that combines extraction/recover and stripping in one stage to extract/recover heavy metals and/or hydrocarbons from water and wastewater. ELM devised a way to clean up heavy metals and/or hydrocarbons from the water and wastewater where its primary chemicals can be recycled and reused.
In this work, the Emulsion Liquid Membrane (ELM) has been enhanced by adding nanoparticles and ionic liquid to significantly improve the recovery of the water-based contaminants of heavy metal and hydrocarbon compounds to near completion in a shorter duration of time and sustain the emulsion stability for longer time.
Recovery of heavy metals of vanadium and lead have been studies separately and in combination where the nanoparticles have been added to the internal aqueous phase and the ionic liquid has been added to the organic phase. A recovery of 97 % in 3min and with emulsion stability exceeding for more than 78 hours have been obtained using 0.01% (W/W) nanoparticles and 5% (V/V) ionic liquid concentration. For hydrocarbon, 4-Nitrophenol compounds were removed effectively by achieving 99% in 1 minute removal with emulsion stability exceeding 6 hours using 0.05% (W/W) nanoparticles and 0.05% (V/V) ionic liquid concentration.
The method is more efficient, cost effective and has a potential for a wide commercial application that could also potentially save entire regional ecosystems from harmful chemicals.
Advisor: Dr. Neil Anderson
Date & Time: Friday, October 22, 2021 at 11:00 AM
Location (Zoom): https://us02web.zoom.us/j/82717971500?pwd=WTRLQW1HZm1scWxoVFRnSnZ5TUtXdz09
Abstract: The Montauk Bridge deck was assessed based on the portable seismic property analyzer and ground penetrating radar data. Based on the analysis of the portable seismic property analyzer data, it was determined that over 65% of bridge conditions were rated serious to poor condition with an average compressive strength of less than 2500 psi; less than 35% of bridge deck conditions were rated fair to good with an average compressive strength over 2500 psi. Based on ground penetrating radar data, it was determined that 72% of the bridge deck was in serious to poor condition, and only 28% of the bridge deck was in fair to good condition. Additionally, the analyses of the ground penetrating radar data indicated possible rebar corrosion in places. For these reasons, it is recommended that the Montauk Bridge’s deck be completely replaced.
The August A. Busch Bridge deck was also assessed using a portable seismic property analyzer and ground penetrating radar tools. Over 90% of the August A. Busch Bridge’s deck was in fair to good condition with an average compressive strength of over 2500 psi. Ground penetrating radar data showed no indication of significant deterioration. the overall bridge deck was determined to be in fair to good condition, and it was recommended that the August A. Busch Bridge deck be inspected every 24 months.
Based on the ground penetrating radar data, plan-view maps were generated that showed the cross-section of the bridge deck and the placement steel bars, along with the dimensions of the steel bars’ covers. The interpretations of the portable seismic property analyzer data correlated well with the interpretations of the ground penetrating radar assessments of both bridges. The interpretations of both data were consistent with the visual inspection, indicating that the ground penetrating radar and portable seismic property analyzer are cost-effective tools to assess bridge deck conditions.
Advisor: Dr. Philip Fraundorf & Dr. Julia E. Medvedeva
Date & Time: Thursday, October 28, 2021 at 10:00 AM
Location (Zoom): https://umsystem.zoom.us/j/94513683737?pwd=N0ZRdWRaWWZIWlpIb29Ba25Hclhjdz09
Abstract: Elemental carbon has important structural diversity, ranging from nanotubes through graphite to diamond. Previous studies of micron-size core/rim carbon spheres extracted from primitive meteorites suggest they formed around such stars via the solidification of condensed carbon-vapor droplets, followed by gas-to-solid carbon coating to form the graphite rims. Similar core/rim particles result from the slow cooling of carbon vapor in the lab. The long-range carbon bond-order potential was used to computationally study liquid-like carbon fixed-volume (1.8 g/cc) periodic boundary (tiled-cube) and containerless (isolated cluster) settings. Relaxations via conjugate gradient and simulated annealing nucleation and growth simulations using molecular dynamics were done to study nucleation seed formation, structural coordination, and the latent heat of fusion. Atomistic results, which agree with independent DFT studies, show an energy preference for pentagon nucleation seeds, sp and sp2 coordination, and a bond defining gap in nearest neighbor histograms. Latent heat of fusion values of 1.015 ± 0.078 eV/atom and 1.178 ± 0.053 eV/atom were determined which agree with values previously determined from separate experimental and computational studies. Analytical models of nucleation and growth derived from classical nucleation theory with numerical models of saturation show insights into the supercooling limits, the onset of solidification, the cluster size distributions, and fast and slow cooling processes such as saturation effects. The low-pressure analytical model predictions for graphene sheet number-density and mass weighted average help explain experimental observations of lab-grown and pre-solar specimens.