Chemistry Commons^™

Comprehensive Silica Removal With Ferric Compounds For Industrial Wastewater Reuse, Ehren D. Baca

Civil Engineering ETDs

Cooling towers, integrated circuit (IC) manufacture and reverse osmosis (RO) generate copious amounts of wastewater high in colloidal and reactive silica inhibiting on-site or synergistic reuse. Silica present in cooling water can reach solubility limits via evaporation and form impervious scale on heat transfer surfaces that decreases efficiency. When water is treated by RO operating at high rejection, silica forms difficult-to-remove scale on the membrane feed side in the form of glassy patches and communities of aggregate particles, inhibiting aspirations for zero liquid discharge. Current methods for silica scale mitigation include abundant dosing with chemical antiscalents or complex operating schemes. …

Chelating Ligands And Nanomaterials Based On Graphene Oxide For The Reduction And Sequestration Of Radiometals And Protein Purification, Sam Groveman

Dissertations, Theses, and Capstone Projects

Nuclear waste remediation and protein purification using immobilized metals can benefit enormously from the design and implementation of novel chelating nanomaterials. Available commercial resins capable of sequestering metals are based on bulk materials such as organic polymers, ceramics, and their composites. The use of two-dimensional nanoplatforms with large surface areas expands the horizon for the research and development of new systems with higher efficiency and lower cost. Fundamental science challenges remain in the synthesis and characterization of these nanomaterials and their integration with known or novel coordinating ligands.

Chemical exfoliation of graphite under strong oxidizing conditions yields graphene oxide (GO) …

Depletion Of Ozone And Reservoir Species Of Chlorine And Nitrogen Oxide In The Lower Antarctic Polar Vortex Measured From Aircraft, T. Jurkat, C. Voigt, S. Kaufmann, J.-U. Grooß, H. Ziereis, A. Dörnbrack, P. Hoor, H. Bozem, A. Engel, H. Bönisch, P. F. Bernath

Chemistry & Biochemistry Faculty Publications

Novel airborne in situ measurements of inorganic chlorine, nitrogen oxide species, and ozone were performed inside the lower Antarctic polar vortex and at its edge in September 2012. We focus on one flight during the Transport and Composition of the LMS/Earth System Model Validation (TACTS/ESMVal) campaign with the German research aircraft HALO (High-Altitude LOng range research aircraft), reaching latitudes of 65°S and potential temperatures up to 405 K. Using the early winter correlations of reactive trace gases with N₂O from the Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS), we find high depletion of chlorine reservoir gases up to ∼40% …

Evaluation Of A Filtration Sorbent For Remediation Of Arsenic In Groundwater, Clement Do

Electronic Theses, Projects, and Dissertations

A commercially available product, PURA PhosLock, was identified and evaluated for use as a sorbent to remove dissolved arsenic (As) from drinking water. Although marketed as a product to remove phosphate in aquaria, it is composed of iron oxide hydroxide (i.e., FeO(OH)), which is also known to adsorb dissolved As species from water. Arsenic was measured using standard methods and Graphite Furnace Atomic Absorption Spectroscopy. A first rough filtration test was performed to see if the PhosLock adsorbed As well. About 50 g of PhosLock was used to filter 10 L of tap water containing 100 ppb As. No detectable …

Crystal Structure Of {N-[(6-Bromopyridin-2-Yl)- (Phenyl)Methylidene]-2,6-Dimethylaniline-Κ²N,N'}- Dichloridozinc Dichloromethane Hemisolvate, Bradley M. Wile

Chemistry and Biochemistry Faculty Scholarship

The solvated title compound, [ZnCl₂(C₂₀H₁₇BrN₂)]·0.5CH₂Cl₂, comprises a bidentate imino­pyridine ligand and two Cl atoms bound to a zinc²⁺ cation in a distorted tetra­hedral arrangement. The chelate bond lengths are consistent with localized C=N double bonds and a C—C single bond, as expected for an unreduced ligand bound to a closed-shell transition metal cation. Apart from weak nonclassical C—HCl hydrogen bonds between the complex mol­ecules and the disordered solvent mol­ecules (occupancy = 0.5), no further significant inter­molecular inter­actions are observed.

Microwave-Assisted Topochemical Manipulation Of Layered Oxide Perovskites: From Inorganic Layered Oxides To Inorganic-Organic Hybrid Perovskites And Functionalized Metal-Oxide Nanosheets, Sara Akbarian-Tefaghi

University of New Orleans Theses and Dissertations

Developing new materials with desired properties is a vital component of emerging technologies. Functional hybrid compounds make an important class of advanced materials that let us synergistically utilize the key features of the organic and inorganic counterparts in a single composite, providing a very strong tool to develop new materials with ”engineered” properties. The research presented here, summarizes efforts in the development of facile and efficient methods for the fabrication of three- and two-dimensional inorganic-organic hybrids based on layered oxide perovskites. Microwave radiation was exploited to rapidly fabricate and modify new and known materials. Despite the extensive utilization of microwaves …

Design And Fabrication Of Nanostructures For The Enhancement Of Photovoltaic Devices, Richard M. Prevost Iii

University of New Orleans Theses and Dissertations

In 2012 the net world electricity generation was 21.56 trillion kilowatt hours. Photovoltaics only accounted for only 0.1 trillion kilowatt hours, less than 1 % of the total power. Recently there has been a push to convert more energy production to renewable sources. In recent years a great deal of interest has been shown for dye sensitized solar cells. These devices use inexpensive materials and have reported efficiencies approaching 12% in the lab. Here methods have been studied to improve upon these, and other, devices. Different approaches for the addition of gold nanoparticles to TiO₂ films were studied. These …

Oxidative C-C Bond Formation Reactivity Of High Valent Nickel And Palladium Complexes, Michael Benjamin Watson

Arts & Sciences Electronic Theses and Dissertations

The development of both palladium and nickel catalysis over the past several decades has led to the ability to perform a multitude of C-C coupling, C-Heteroatom coupling, and C-H functionalization reactions. These reactions typically utilize a catalytic cycle involving Pd0/II/IV and Ni0/II. While using these types of catalytic cycles one can create a multitude of different hard to make bonds, it is always important to keep expanding what we view as potential catalytic intermediates to keep developing new cycles capable of new transformations. One such way to expand our knowledge of these catalytic cycles is to look at the oxidation …

High-Resolution Three-Dimensional Nmr Structure Of The Kras Proto-Oncogene Promoter Reveals Key Features Of A G-Quadruplex Involved In Transcriptional Regulation, A. Kerkour, J. Marquevielle, S. Ivashchenko, Liliya A. Yatsunyk, J.-L. Mergny, G. F. Salgado

Chemistry & Biochemistry Faculty Works

Non-canonical base pairing within guanine-rich DNA and RNA sequences can produce G-quartets, whose stacking leads to the formation of a G-quadruplex (G4). G4s can coexist with canonical duplex DNA in the human genome and have been suggested to suppress gene transcription, and much attention has therefore focused on studying G4s in promotor regions of disease-related genes. For example, the human KRAS proto-oncogene contains a nuclease-hypersensitive element located upstream of the major transcription start site. The KRAS nuclease-hypersensitive element (NHE) region contains a G-rich element (22RT; 5′-AGGGCGGTGTGGGAATAGGGAA-3′) and encompasses a Myc-associated zinc finger-binding site that regulates KRAS transcription. The NEH region …

Effects Of Processing Parameters On Properties Of Novel Silica-Filled Polysiloxane Materials, Kyle W. Schwenker

Electronic Theses & Dissertations

Polysiloxanes are a class of materials that possess high temperature stability and the ability to remain flexible at extremely low temperatures. Their elastomers generally exhibit low strength and have poor mechanical properties unless reinforced with fillers. Reinforcement can be accomplished by compounding reinforcing silica fillers with polysiloxanes via twin-screw extrusion compounding that vigorously mixes the fillers into a polymer matrix. In this thesis, a lab-scale twin-screw extruder was utilized to compound thermoplastic materials to determine the effects of processing on thermoplastics material properties, as well as to determine the extruder’s compounding effectiveness. Processing via lab-scale twin-screw extrusion did not negatively …

Real Time Monitoring Of Photocatalysis: An Application And Expansion Of The Quartz Crystal Microbalance, Perrin Godbold

Senior Honors Projects, 2010-2019

There are many applications of photocatalytic chemistry, with hundreds of researchers investigating photocatalytic materials. Another method of investigation could aid these researchers and contribute significantly to this field. This study attempts to develop a new method of analysis by expanding the capabilities of the Quartz Crystal Microbalance (QCM) into the realm of photocatalysis. We coated QCM crystals with the stable and well-known photocatalyst, titanium dioxide, and utilized these coated crystals to begin to develop an analysis procedure for our modified instrument. Some indication of the QCM’s sensitivity was seen, but the UV irradiation elicited a frequency change independent of the …

Synthesis And Characterization Of Novel Single-Site Titanosilicates With Targeted Connectivites And Geometries As Selective Oxidation Catalysts, Lena Elenchin

Doctoral Dissertations

The primary focus of this research was to synthesize and characterize two families of titanosilicate catalysts, first generation and second generation, that were single site, atomically dispersed with targeted connectivities to the silicate matrices but had different geometries about the active sites. First generation catalysts have tetrahedral active sites, while second generation catalysts have altered geometries for a more accessible active site, but maintain the same targeted connectivities.

A building block methodology is employed to prepare single site, isolated, atomically dispersed titanium active sites within a silicate matrix. The synthetic approach uses a molecular precursor, i.e., building block and the …

Thermally Robust And Redox Active Catalysts: Studying Their Behavior For Ethylene And L-Lactide Polymerization, Lauren Ashley Brown

Doctoral Dissertations

The development of homogenous single-site catalysts has significantly impacted the field of organometallic chemistry. The well-defined structures of homogenous catalysts make it less cumbersome to understand and develop methods to tailor these compounds for specific catalytic processes. Currently, polymerization catalysis is a major division in organometallic chemistry due to the global demand for polymeric materials such as polyethylene (PE) and polypropylene (PP), based on their low-cost feedstock, remarkable mechanical properties, and their use in a wide range of applications. However, bioplastics have become a highly sought-after alternative to conventional petrochemical-based plastics due to their biodegradability and derivatization from renewable resources. …

Ion Separations: Achieving Selectivity Through Rational Design In Solvent Extraction And Crystallization Systems, Neil Justin Williams

Doctoral Dissertations

The selective separation of ions from aqueous solutions has been a difficult challenge to address in the separation sciences. The difficulties associated with selective separations of ions are due to a multitude of chemical and physical differences between them. Additionally, the term ions encompass both positively charged cations and their counter parts the negatively charge anions. The work covered in this dissertation discusses the difficulties encountered during the selective separation of both oxoanions and cations. Apart from the Introduction Chapter 1 and Conclusion Chapter 10, the selective separations oxoanions and cations will be discussed separately with the dissertation being …

Improving Predictive Capabilities Of Classical Cascade Theory For Nonproliferation Analysis, David Allen Vermillion

Doctoral Dissertations

Uranium enrichment finds a direct and indispensable function in both peaceful and nonpeaceful nuclear applications. Today, over 99% of enriched uranium is produced by gas centrifuge technology. With the international dissemination of the Zippe archetypal design in 1960 followed by the widespread illicit centrifuge trafficking efforts of the A.Q. Khan network, traditional barriers to enrichment technologies are no longer as effective as they once were. Consequently, gas centrifuge technology is now regarded as a high-priority nuclear proliferation threat, and the international nonproliferation community seeks new avenues to effectively and efficiently respond to this emergent threat.

Effective response first requires an …

The Role Of Sulfur Dioxide In Stratospheric Aerosol Formation Evaluated By Using In Situ Measurements In The Tropical Lower Stratosphere, A. W. Rollins, T. D. Thornberry, L. A. Watts, P. Yu, K. H. Rosenlof, M. Mills, E. Baumann, F. R. Giorgetta, T. V. Bui, M. Höpfner, P. F. Bernath

Chemistry & Biochemistry Faculty Publications

Stratospheric aerosols (SAs) are a variable component of the Earth's albedo that may be intentionally enhanced in the future to offset greenhouse gases (geoengineering). The role of tropospheric-sourced sulfur dioxide (SO₂) in maintaining background SAs has been debated for decades without in situ measurements of SO₂ at the tropical tropopause to inform this issue. Here we clarify the role of SO₂ in maintaining SAs by using new in situ SO₂ measurements to evaluate climate models and satellite retrievals. We then use the observed tropical tropopause SO₂ mixing ratios to estimate the global flux of …

Controlled Synthesis And Utilization Of Metal And Oxide Hybrid Nanoparticles, Cameron Cowgur Crane

Graduate Theses and Dissertations

This dissertation reports the development of synthetic methods concerning rationally-designed, hybrid, and multifunctional nanomaterials. These methods are based on a wet chemical, solution phase approach that utilizes the knowledge of synthetic organic and inorganic chemistry to generate building blocks in solution for the growth of nanocrystals and hybrid nanostructures. This work builds on the prior knowledge of shape-controlled synthesis of noble metal nanocrystals and expands into the challenging realm of the more reactive first row transition metals. Specifically, a microemulsion sol-gel method was developed to synthesize Au-SiO2 dimers as precursors for the synthesis of segmented heterostructures of noble metals that …

An Electrochemical Characterization Of A Vanadium-Based Deoxydehydration Catalyst, Joel Eric Baker

Graduate Theses and Dissertations

Alternative methods for the conversion of polyols into olefins, be it for carbon storage or hydrocarbon fuel production, have become prevalent in today’s chemical industry. One process in particular, deoxydehydration (DODH) has been proven effective in taking sustainable biomass derivatives and converting them through the utilization of various homogenous metal catalysts. While this process may show productive yields and material conversion, it is hindered by the need of a sacrificial reductant. This makes a novel process economically unviable and relatively unused outside of scientific research. That fact begs the question: Can the process be improved? It is proposed here that …

29si Nmr And Saxs Investigation Of The Hybrid Organic-Inorganic Glasses Obtained By Consolidation Of The Melting Gels, Andrei Jitianu, Sylvian Cadars, Fan Zhang, Gabriela Rodriguez, Quentin Picard, Mario Aparicio, Jadra Mosa, Lisa C. Klein

Publications and Research

This study is focused on structural characterization of hybrid glasses obtained by consolidation of melting gels. The melting gels were prepared in molar ratios of methyltriethoxysilane (MTES) and dimethyldiethoxysilane (DMDES) of 75%MTES-25%DMDES and 65%MTES-35%DMDES. Following consolidation, the hybrid glasses were characterized using Raman, ²⁹Si and ¹³C Nuclear Magnetic Resonance (NMR) spectroscopies, synchrotron Small Angle X-Ray Scattering (SAXS) and scanning electron microscopy (SEM). Raman spectroscopy revealed the presence of Si–C bonds in the hybrid glasses and 8-membered ring structures in the Si–O–Si network. Qualitative NMR spectroscopy identified the main molecular species, while quantitative NMR data showed that the ratio …

Functionalized Silica Gel For Adsorption Of Cesium From Solution, Kenneth Marshall Seaton Iii

Electronic Theses and Dissertations

Mesoporous silica gel containing embedded phosphotungstic acid (PTA) was synthesized by sol-gel co-condensation of tetraethyl orthosilicate with PTA in acidic media. The obtained material had high Brunauer-Emmett-Teller Theory (BET) surface area and pore volume. A characteristic band of the Keggin structure of PTA was present in its FT-IR spectrum while its X-ray diffraction patterns were absent. This proved the embedding of PTA on a sub-molecular level and not as a second phase. Acidic sites were determined by neutralization with base in aprotic solvent, followed by titration of the remaining base with an acid. The material demonstrated high adsorption capacity of …

Homogeneous Ligand-Centered Hydrogen Evolution And Hydrogen Oxidation : Exploiting Redox Non-Innocence To Drive Catalysis., Andrew Z. Haddad

Electronic Theses and Dissertations

Hydrogen is a promising carbon-free fuel / energy carrier and is an essential building block for many industrial and agricultural processes. Rising energy demands have ignited interest in the development of carbon-free and carbon neutral energy sources. In this context, hydrogen is an attractive candidate—being energy-dense, carbon-free—and easily accessible through a two-electron reduction of water. Accordingly, many electrochemical homogeneous catalyst systems have been studied, with a focus on understanding the mechanism of hydrogen evolution proceeding through metal-hydride intermediates. However, there has been a renaissance in hydrogen evolution reaction (HER) catalyst design, with many groups implicating ligand redox non-innocence as a …

Design Of 3d Macroporous Inverse Opal Tio2 Binary And Ternary Composites Sensitized With Gold Nanoparticles And Cds Quantum Dots For Photocatalysis, Daniel A. Corella

Master of Science in Chemical Sciences Theses

Materials composed of titanium (IV) oxide (TiO₂) have received enormous scientific interest due to titania’s abundance, non-toxicity, and photocatalytic proficiency, however its large band gap limits its applicability under ambient conditions. Various attempts have been made to incorporate titania into composite systems to sensitize it for activity under a broader range of wavelengths. One such method includes utilizing narrow band gap semiconductors to form an electron transfer process analogous to photosynthesis referred to as a Z-scheme. Z-scheme systems can catalyze the decomposition of aqueous pollutants via generation of reactive oxygen species after input of sunlight. This work reports …

Syntheses, Structures And Magnetic Properties Of Cyano-Bridged Transition Metal Compounds, Uma Prasad Mallik

Dissertations

To investigate the hypotheses, that systematically changing the electronic and relative sizes of tricyanido building blocks will tune magnetic properties of their cluster derivatives, we prepared two new tricyanido pyrazolylborate complexes, [NEt₄][(Tp*^Me)­Fe(CN)₃]­·H₂O and [NEt₄]­[(Tp^*Bn)­Fe^III(CN)₃]­·H₂O·MeOH, and investigated their self-assembly. The new building blocks were prepared, structurally characterized, and their coordination chemistry explored to prepare small molecule-based magnetic materials.

Three bent trinuclear ferromagnetic cluster derivatives of {[(Tp^*Me)­Fe^III(CN)₃]_2­[Ni^II(L)₂]}·n(solvent) [L = …

Metalation And Structural Properties Of Apo-Metallothioneins, Gordon W. Irvine

Electronic Thesis and Dissertation Repository

Metals are required by a quarter of all proteins to achieve their biological function, whether in an active site involved in catalytic chemistry or in a structural capacity. Metals are tightly regulated at the cellular level due to their propensity to cause unwanted side reactions and to be scavenged for use by pathogens. One of the proteins involved in this regulation of metal homeostasis is metallothionein (MT) which is a small, cysteine rich protein primarily involved in the regulation of zinc and copper homeostasis and heavy metal detoxification. MT is unique in its high cysteine content (~30% of the residues), …

Characterization Of N-Polydentate Copper(Ii)-Alkylperoxo Complexes, Bruce Pella

Research Horizons Day Posters

No abstract provided.

Modification Of A Junior-Level Capstone Course To Incorporate Scientific Writing, Bradley M. Wile

Chemistry and Biochemistry Faculty Scholarship

No abstract provided.

Catalyzed Synthesis Of Zinc Clays By Prebiotic Central Metabolites, Marcelo I. Guzman, Ruixin Zhou, Kaustuv Basu, Hyman Hartman, Christopher J. Matocha, S. Kelly Sears, Hajatollah Vali

Chemistry Faculty Publications

How primordial metabolic networks such as the reverse tricarboxylic acid (rTCA) cycle and clay mineral catalysts coevolved remains a mystery in the puzzle to understand the origin of life. While prebiotic reactions from the rTCA cycle were accomplished via photochemistry on semiconductor minerals, the synthesis of clays was demonstrated at low temperature and ambient pressure catalyzed by oxalate. Herein, the crystallization of clay minerals is catalyzed by succinate, an example of a photoproduced intermediate from central metabolism. The experiments connect the synthesis of sauconite, a model for clay minerals, to prebiotic photochemistry. We report the temperature, pH, and concentration dependence …

Synthesis, Kinetic And Catalytic Studies Of Manganese Complexes With Corrole And Porphyrin Ligands, Haleh Jeddi

Masters Theses & Specialist Projects

High-valent transition metal-oxo intermediates play a significant role in the catalytic cycle of the ubiquitous cytochrome P450 enzymes and in biomimetic catalytic systems. In this work, manganese(III) porphyrin and corrole systems (2) were synthesized and characterized by UV-vis absorbance and 1H-NMR, matching literaturereported spectroscopic data. Manganese(V)-oxo corroles (3) and a manganese(IV)-oxo porphyrin (4) were successfully generated by chemical oxidation using mchloroperoxybenzoic acid (m-CPBA), and their oxidation reactions with organic reductants were comparatively investigated. Results from single-turnover kinetic studies indicate that in the tris(pentafluorophenyl)corrole system (3a), the active oxidizing intermediate differs in different solvents. The active oxidizing intermediate in acetonitrile is …

Effects Of Binding Affinity Between Bovine Serum Albumin And Platinum Drugs, Nathan Puckett

Masters Theses & Specialist Projects

Platinum complex drugs such as cisplatin have been used as highly successful chemotherapy drugs since the 1970s. We are interested in how the ligands attached to cisplatin analogs influences their reactivity with biologically relevant targets along with time and amount. For this study, reactions were conducted to determine the reactivity between different platinum compounds and the protein bovine serum albumin. Various platinum compounds with different ligands were reacted in varying amounts with albumin in ammonium acetate buffer for either 1 hour, 4 hours, or 24 hours. Each reaction was quenched after the designated reaction time by dialysis and the platinum …

Thickness-Properties Synergy In Organic–Inorganic Consolidated Melting-Gel Coatings For Protection Of 304 Stainless Steel In Nacl Solutions, Mario Amapricio, Andrei Jitianu, Gabriela Rodriguez, Kutaiba Al-Marzoki, Mihaela Jitianu, Jadra Mosa, Lisa C. Klein

Publications and Research

Homogeneous and crack-free methyl-substituted organic–inorganic hybrid glass coatings (thickness up to 10 μm) were deposited on AISI 304 stainless steel. Different hybrid glasses obtained fromconsolidation of the diluted melting gels with various methyltriethoxysilane (MTES)/dimethyldiethoxysilane (DMDES) ratios were evaluated considering chemical structure, coating adhesion and corrosion protection. The 70MTES/30DMDES (molar%) melting-gel coating provided improved corrosion protection for this steel due to the synergy of different properties: a highly cross-linked inorganic structure, a coating plasticity based on the hybrid network, and a good adhesion to the substrate through hydroxyl groups. Electrochemical results showa good barrier film with a passive range of 500 …