Other Chemical Engineering Commons^™

Adsorption And Transport Of Colloids At Interface And In Bulk, Jingyun Lee

LSU Doctoral Dissertations

Colloids are suspensions of microscopic insoluble particles dispersed in a continuum phase such as liquid or gas. Colloids are found in our everyday life from food and cosmetic industries to pharmaceutical and biomedical applications. Depending on a global minimum of the free-energy landscape, colloidal suspensions can be classified as two major classes: equilibrium or active colloidal system. This Ph.D dissertation presents strategies to engineer equilibrium self-assembled structures and out-of-equilibrium active matter using various interparticle forces.

First, we introduce the means to promote the equilibrium self-assembled structures driven by adsorption of colloids at interface. Typically, adsorption of colloids at interface is …

Gold-Semiconductor Photocatalysts For Water Treatment Under Visible And Ultraviolet Light, Daniel Willis

LSU Doctoral Dissertations

Water scarcity threatens the lives of millions of people worldwide. It is imperative to improve the energy efficiency and affordability of water treatment methods to avoid a looming water-energy crisis. To meet this challenge, I have pursued research on the use of sunlight—our most reliable and abundant source of energy—to drive water treatment through photocatalysis. I explored the literature and found gold-semiconductor materials to hold promise for harvesting sunlight and catalyzing the breakdown of waterborne contaminants. Initially, I designed a novel optical cavity with gold (Au) nanoparticles on a zinc oxide / titania (TiO₂) / aluminum film stack …

Adsorption And Reconfiguration Of Amphiphiles At Silica-Water Interfaces: Role Of Electrostatic Interactions, Van Der Waals Forces And Hydrogen Bonds, Yao Wu

LSU Doctoral Dissertations

The ability to explore and predict metastable structures of hybrid self-assemblies is of central importance for the next generation of advanced materials with novel properties. As compared to their thermodynamically stable forms, the kinetically stabilized materials show improved functionality potentially over their stable counterparts. The self-assembly processes usually originate from weak intermolecular interactions, involving a dynamic competition between attractive and repulsive interactions. These weak forces, including van der Waals (vdW), electrostatic interaction and the hydrogen bonding (H-bonding), can be tuned by external stimuli, e.g., confinement, temperature and ionization, and consequently driving hybrid materials into different configurations. It is challenging to …

Tunable Luminescence Of Rare Earth Doped Nanophosphors Via Adaptive Optical Properties Of Transition Metals, Pragathi Darapaneni

LSU Doctoral Dissertations

Over the past decades, the development of light-emitting diodes (LEDs) to produce a wide range of wavelengths has revolutionized the solid-state lighting industry due to their higher energy efficiency and operational lifetimes. These LEDs employ rare earth (RE) doped phosphors due to their stable emission wavelengths which can be amplified when sensitized by other RE dopants (Yb, Ce) or shell layer passivation. However, there has been a push to replace the RE elements in LEDs due to increased socioeconomic issues. One proposed alternative, transition metal (TM) dopants, is typically avoided due to their susceptibility to the local crystal environment resulting …

Noble-Transition Alloy Absorbers For Near-Infrared Hot-Carrier Optoelectronics, Sara Karoline Figueiredo Stofela

LSU Doctoral Dissertations

Optoelectronics is the field of technology concerned with the study and application of electronic devices that source, detect and control light. Here we focus on the optical communications field which relies on optical fiber systems to carry signals to their destinations operating in the near-infrared range. To improve the performance of current optical fiber systems, one of the paths is to develop better near-infrared photodetectors.

The current group of materials used for near-infrared photodetection relies in the III-V semiconductor family. Although their spectral photosensitivity correlates well with the near-infrared, response time performance and electronic circuit integration remain limited for this …

The Effects Of Temperature On The Yields Of Aliphatic And Aromatic Products From The Supercritical Pyrolysis Of 1-Octene, Elizabeth Anne Hurst

LSU Doctoral Dissertations

Prior to their combustion, fuels for future high-speed aircraft are expected to experience supercritical conditions, leading to the production of polycyclic aromatic hydrocarbons (PAH), precursors to solid carbonaceous deposits, via pyrolytic reactions. These solid deposits can clog fuel-transfer lines, causing unsafe aircraft operation. To prevent the formation of fuel-line deposits, it is critical to understand the reaction pathways that lead to PAH formation in the supercritical fuel pyrolysis environment.

To better understand the role of large 1-alkenes in PAH formation, supercritical pyrolysis experiments with model fuel 1-octene, a representative 1-alkene product from supercritical n-alkane pyrolysis, have been performed. The …