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Articles 1 - 12 of 12
Full-Text Articles in Physical Sciences and Mathematics
Synthesis Of The Diazonium Zwitterionic Polymer/Monomer For Use As The Electrolyte In Polymer Electrolyte Membrane (Pem) Fuel Cells, Josiah Marshall
Synthesis Of The Diazonium Zwitterionic Polymer/Monomer For Use As The Electrolyte In Polymer Electrolyte Membrane (Pem) Fuel Cells, Josiah Marshall
Electronic Theses and Dissertations
My research goals are to synthesize new zwitterionic perfluorosulfonimide (PFSI) monomer/polymers. They are expected to replace traditionally used perfluorosulfonic acid (PFSA) polymers as the electrolyte in PEM fuel cells. For the PFSI monomer preparation, we designed a nine-step synthesis route. Thus far, I have successfully completed the synthesis of 4- (2-bromotetrafluoroethoxy)-benzenesulfonyl amide, 4-acetoxybenzenesulfonic acid sodium salt, and 4-chlorosulfonyl phenyl acetate. The coupling reaction of 4-(2-bromotetrafluoroethoxy)- benzenesulfonyl amide with 4-chlorosulfonyl phenyl acetate, was troublesome due to slow reaction kinetics and byproducts. Additionally, I did a methodology study for the homopolymerziation of the perfluoro 3(oxapent-4-ene) sulfonyl fluoride monomer. We compared the weight …
Mesoporous Adsorbents For Perfluorinated Compounds, Bertha Lotsi
Mesoporous Adsorbents For Perfluorinated Compounds, Bertha Lotsi
Electronic Theses and Dissertations
Effective adsorbents for polyfluorinated compounds (PFCs) were successfully prepared. And they were tested in the adsorption of perfluorooctanoic and perfluorooctanesulfonic acids. Bridged silsesquioxanes containing secondary and tertiary amino groups were synthesized by sol-gel condensation of bis[3-(trimethoxysilyl)propyl]amine and bis[3-(methylamino)propyl]-trimethoxysilane in acidic media with surfactants. Obtained materials are mesoporous with a high BET surface area. They combine high structural stability with a high concentration of surface amino groups serving as adsorption sites. Batch adsorption tests demonstrated their extremely high adsorption capacity on PFCs: in some experiments, it reached up to 88% of the adsorbent weight. Adsorption of PFCs changed the surfaces of …
Immobilization Of Phosphotungstic Acid On Silica Surface For Catalytic Alkylation Of Aromatic Compounds, Anastasia Kuvayskaya
Immobilization Of Phosphotungstic Acid On Silica Surface For Catalytic Alkylation Of Aromatic Compounds, Anastasia Kuvayskaya
Electronic Theses and Dissertations
Superacidic mesoporous materials containing covalently embedded PTA were synthesized by sol-gel method. Tetraethyl orthosilicate (TEOS) and phosphotungstic acid (PTA) were used as precursors in the synthesis, ionic and nonionic surfactants were used as pore-forming agents, the reaction proceeded in acidic media. TEM images revealed mesoporous structure with embedded PTA clusters. FT-IR spectra of obtained materials contained characteristic bands of PTA at 957 cm-1. Synthesized catalysts had high BET surface area and high concentration of acidic sites. Alkylation of 1,3,5-trimethylbenzene by 1-decene demonstrated high catalytic activity. The catalyst obtained with Pluronic P123 as a template was the most effective and resulted …
Preparation Of Folic Acid-Carbon Dots-Doxorubicin Nanoparticles As Targeting Tumor Theranostics, Samson Dada
Preparation Of Folic Acid-Carbon Dots-Doxorubicin Nanoparticles As Targeting Tumor Theranostics, Samson Dada
Electronic Theses and Dissertations
Carbon dots (CDs) have attracted much attention as an excellent gene/drug delivery and biological imaging agent for early cancer theranostics. In this study, we prepared two series of nanoparticles (NPs), which are composed of (CDs) with a targeting agent, folic acid (FA), and a chemotherapeutic agent Doxorubicin (Dox). All the NPs and their intermediates were characterized using ultraviolet-visible spectroscopy (UV-vis), fluorescence spectroscopy, and Fourier transform-infrared spectroscopy (FT-IR). The drug loading capacity (DLC) and drug loading efficiency (DLE) of two series of FA-CDs-Dox were assessed using UV-vis absorption spectroscopy at the wavelength of 485 nm. Both showed good DLE and DLC …
Development Of Granulated Adsorbent For Clean-Up Of Water Contaminated By Cesium, Esther Alorkpa
Development Of Granulated Adsorbent For Clean-Up Of Water Contaminated By Cesium, Esther Alorkpa
Electronic Theses and Dissertations
A study was conducted on sol-gel synthesis of an adsorbent (phosphotungstic acid embedded in silica gel, H-PTA/SiO2) of radioactive cesium. A novelty of this work is covalent bonding of PTA to the surface of solid support that prevents leaching from the surface of the material. The sample was granulated with a binder, aluminium oxide (γ-Al2O3). Solid-state NMR and FT-IR spectroscopy were used to confirm the presence of Keggin units of PTA in the bound materials. Thermal analysis of H-PTA/SiO2 - γ-Al2O3 (50 %) showed that the water content in the …
Deposition Of Platinum Particles On Surface-Modified Carbon Ultramicroelectrodes, Caitlin Millsaps
Deposition Of Platinum Particles On Surface-Modified Carbon Ultramicroelectrodes, Caitlin Millsaps
Undergraduate Honors Theses
Nanoparticles are used as electrocatalysts due to their large surface area-to-volume ratios. Most studies of nanoparticle electrocatalysis are performed on collections of particles on a support, which represent ensemble average behavior influenced by spatial distribution of the nanoparticles. Therefore, recent emphasis has been placed on analyzing electrocatalytic behavior of single particles. The focus here is to develop carbon ultramicro- and nanoelectrode platforms for studying the electrocatalytic properties of single metal nanoparticles. Ultramicroelectrodes were prepared using chemical vapor deposition of carbon in pulled quartz capillaries. Electrode diameters were determined by cyclic voltammetry. Electrodes were modified using a soft nitriding technique to …
Functionalized Silica Gel For Adsorption Of Cesium From Solution, Kenneth Marshall Seaton Iii
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 …
Immobilization Of Heteropolyacids In Silica Gel, Opeyemi Adetola
Immobilization Of Heteropolyacids In Silica Gel, Opeyemi Adetola
Electronic Theses and Dissertations
Silica gels containing incorporated heteropolyacids (HPAs) were synthesized in acidic media by co-condensation of tetraethoxysilane (TEOS) with phosphotungstic or phosphomolybdic acids using sol-gel technique. Effect of the synthesis conditions on their structure and morphology was studied. Yields of modified materials were some lower as compared to non-modified silica gels. All materials were mesoporous but contained micropores in their structures. Presence of bands of Keggin’s structures in FT-IR spectra along with absence of XRD patterns of crystalline HPAs confirmed their fine incorporation into silica network. Particle sizes of modified materials were 800-1100 nm excepting for W-containing sample obtained with trimethylstearylammonium chloride. …
Studies On The Preparation, Immobilization, And Luminescence Properties Of Zinc Oxide (Zno)Quantum Dots, Yasemin Hakat
Studies On The Preparation, Immobilization, And Luminescence Properties Of Zinc Oxide (Zno)Quantum Dots, Yasemin Hakat
Electronic Theses and Dissertations
Quantum dots are a part of very important our technological future because of their intriguing and useful properties. These properties are different in character from those of the corresponding bulk material. Quantum dots are inorganic artificial semiconductor nanocrystal whose electrons influence their physical and chemical properties. Zinc oxide quantum dots were synthesized through an ethanol based precipitation via colloidal synthesis method at various pH values. Various emission colors were obtained because the excited quantum dots of various sizes emitted specific wavelengths of light. The emission spectra indicated that the pH dependent quantum dots were successfully synthesized. Zinc oxide quantum dots …
Mesoporous Functionalized Materials For Post-Combustion Carbon Dioxide Capture., Kolade Omoniyi Ojo
Mesoporous Functionalized Materials For Post-Combustion Carbon Dioxide Capture., Kolade Omoniyi Ojo
Electronic Theses and Dissertations
Novel highly functionalized hybrid organic-inorganic materials were synthesized by polycondensation of bis[3-(trimethoxysilyl)propyl]amine in presence of cationic and anionic surfactants. Reaction media strongly affected gelation time. Thus, in basic media gelation occurred immediately while acid increased gelation time. Material structures were studied by IR spectroscopy, porosimetry, XRD, and SAXS methods. In spite of the absence of an inorganic linker, obtained bridged silsesquioxanes had mesoporous structure. A material prepared in the presence of dodecylamine as a template had higher surface area and narrow pore size distribution while the use of sodium dodecylbenzene sulfate resulted in formation of mesopores with wide size ranges. …
Studies Of Titanium Dioxide Nanoparticles And Surfactants Effects, Singly And In Combinations, On Luminescence Intensity Of Some Aromatic Compounds., Charles Anim Odame-Ankrah
Studies Of Titanium Dioxide Nanoparticles And Surfactants Effects, Singly And In Combinations, On Luminescence Intensity Of Some Aromatic Compounds., Charles Anim Odame-Ankrah
Electronic Theses and Dissertations
Luminescence techniques are sensitive, selective, and widely used in analysis. Luminescence intensity is attenuated by quenchers. This research has focused on the use of surfactants such as CTAB, SDS, and TX-100 singly or together with TiO2 nanoparticles to evaluate their individual and combined effects on some fluorescent aromatic compounds such as pyrene, fluoranthene, anthracene, phenanthrene, and carbazole. Rutile phase TiO2 was synthesized using the low temperature sol-gel method. Carbazole and phenanthrene were severely quenched by all surfactants singly or in combination with TiO2. Anthracene and fluoranthene showed some enhancement in their luminescence intensity. The most dramatic …
Electrochemical Remedy And Analysis For The Environment Based On The New Polymer-Dna Composite Material., Noor Feuza Hussain
Electrochemical Remedy And Analysis For The Environment Based On The New Polymer-Dna Composite Material., Noor Feuza Hussain
Electronic Theses and Dissertations
In this work a new material, the conducting polymer-DNA composite, has been reported for the first time due to its promise in micro extraction, transfer, and release of cations under controlled potential conditions by using electrochemically assisted solid phase micro extraction (SPME). The Polypyrrole/DNA composite can be formed easily by oxidation of pyrrole monomers in the presence of chromosomal DNA by electropolymerization. Environmental significant pollutants such as Cd, Pb, Hg, Co, Zn, Cu, and Bi metal ions can be extracted from the aqueous solution and are able to be transferred to another medium defined as the release solution where the …