Thesis (Ph. D.)--University of Wisconsin--Madison, 1975. / Typescript. Vita. Description based on print version record. Includes bibliographical references (leaves 135-144).

Voltammetric determination of 2-methoxy-5-nitrophenol was studied using DC voltammetry (DCV) and differential pulse voltammetry (DPV) at a carbon film electrode (CFE) and a meniscus modified silver solid amalgam electrode (m-AgSAE). Conditions were found for its determination by DCV and DPV at CFE in Britton - Robinson buffer within concentration range 1.10-4 - 1.10-6 mol.l-1 . Using adsorptive stripping voltammetry (AdSV) m-AgSAE in Britton - Robinson buffer pH 2,0 compound this determined in the concentration range (2 - 10) .10-7 mol.l-1 with a limit of detection 3,6.10-7 mol.l-1 . Using a combination of DPV with solid phase extraction (SPE) for determination of 2-methoxy-5-nitrophenol in river water, limit of detection 6,6.10-8 mol.l-1 was abtained. Using cyclic voltammetry (CV) at m-AgSAE and at CFE mechanism of electrochemical reduction 2-methoxy-5-nitrophenol was proposed.

Toxic waste disposal problems have become enormous due to the proliferation of xenobiotic compounds for use in agricultural, industrial and numerous other applications. Organophosphate (OP) pesticides are commonly used in agriculture and their toxicity is associated with inhibition of cholinesterase in the exposed organism. Some OPs have been shown to produce OP-induced delayed neuropathy (OPIDN). The overall goal of the work described in this thesis was to develop bacterial consortia to remediate hazardous substances at significantly higher rates than found with natural systems. Specifically, degradation of methyl parathion (MP) by hydrolysis with a genetically engineered Escherichia coli was investigated along with degradation of one of the resulting products, p-nitrophenol (PNP), by Sphingobium chlorophenolicum ATCC 53874. Simultaneous degradation of both MP and PNP was investigated using a consortium of a genetically engineered Escherichia coli and a native S. chlorophenolicum. Concentrations of MP and PNP were measured by high performance liquid chromatography (HPLC). Non-growing freely suspended recombinant OPH+ E. coli cells efficiently degraded MP without addition of nutrients for growth. Maximum reactor productivity was found with a biomass concentration of 25 g/L. Substrate inhibition did not occur up to 3 g MP/L. The simple Michaelis-Menten kinetic model for enzymatic reactions provided a good fit of the degradation data with Vm=11.45 ??mol/min??g-biomass and Km=2.73 g/L. B. cepacia failed to degrade PNP under the experimental conditions evaluated, so further studies were not conducted. Growing cultures of S. chlorophenolicum degraded PNP at concentrations up to 0.1 g/L without a lag phase in mineral salts glutamate medium. Parameters such as initial pH, growth medium and growth stage for addition of PNP were important degradation factors. The bacterium exhibited substantial growth in the degradation process. Hydroquinone (HQ) or nitrocatechol (NC) were not identified as products of PNP degradation. The recombinant OPH+ E. coli and S. chlorophenolicum consortium failed to degrade PNP when starting with higher concentrations of MP. The presence of organic solvent in the bacterial consortium degradation medium negatively affected the degradation of PNP. The genetically engineered organism efficiently degraded high concentrations of MP, but the resulting high concentration of intermediate product (PNP) inhibited growth of the native type organism. Biodegradation by consortia of genetically engineered non-growing and native-type organisms generally will be limited by the growing native-type organism.

Techn. Hochsch., Diss., 2001--Aachen.

No description available.

Mesoporous silica materials containing microporous cavities provided by covalently bound ¦Â-cyclodextrin (CD ICS) were synthesized by co-condensation of a ¦Â-CD functionalized triethoxy silane (CD ICL) with tetraethyl orthosilicate (TEOS) by using neutral amine surfactants as structure directing agents (SDA). CD ICL was prepared by reacting ¦Â-CD with 3-isocyanatopropyltriethoxysilane. IR spectroscopy of CD ICL showed complete disappearance of isocyanato group at 2270 cm-1. 1H NMR results indicate an average of four isocyanate linkers covalently attached to random hydroxyl substituents of each molecule of ¦Â-CD. <p> Nine different CD ICS materials were synthesized using dodecylamine, tetradecylamine or hexadecylamine with ¦Â-CD (2, 4, and 6 mol %) with respect to TEOS. The incorporation of ¦Â-CD within the mesoporous framework was supported by IR, Raman, MALDI TOF MS, solid state 13C NMR CP-MAS and TGA results. Small angle X-ray diffraction results showed a peak at 2¦È ¡Ö 2.20, supporting the presence of an ordered silica mesostructure framework. For materials with same CD loading, the surface area and pore volume doubled as the surfactant from dodecylamine to hexadecylamine. However, as the CD loading increased from 2% to 6%, the surface area decreases by a factor of ~ 1.5. <p>MALDI TOF mass spectrometry showed two peaks at m/z 1157 a.m.u. and 1173 a.m.u. for [¦Â-CD + Na]+ and [¦Â-CD + K]+ respectively due to desorption of ¦Â-CD from the walls of the silica matrix. The 13C NMR CP MAS results showed 13C signals in the region ¦Ä=60-110 ppm due to the nuclei of ¦Â-CD. CD ICS materials were found to be effective as a sorbent in both gas and aqueous phases, respectively. The sorption capacity (mmol/g) of p-nitrophenol increased from 61% to 84% with an increase of CD loading from 2% to 6% and as the alkyl chain length of the SDA increases from dodecylamine to hexadecylamine. The adsorption isotherm of CH3Cl in the gas phase and that of p-nitrophenol in the aqueous phase at ambient temperature adopts a multilayer model of adsorption.

Naphthenic acids (NAs) are a group of carboxylic acids that are found in hydrocarbon deposits such as the oil sands bitumen. These compounds are a well-known corrosive agent and a toxic component in the oil sands process water (OSPW). Due to Alberta’s zero discharge policy, OSPW cannot be released and must be stored until toxic components like NAs are remediated. One technique that has shown potential is to physically adsorb NAs onto a copolymer generated from economical biomaterials. Therefore, the project can be divided into three sections: 1) Synthesis of β-cyclodextrin (β-CD) copolymer for the sorption of p-nitrophenol (PNP); 2) Synthesis of chitosan-based copolymers (Chi-Glu) for the sorption of PNP; 3) Sorption of carboxylates and NAs using Chi-Glu copolymers. PNP sorption was used as a probe to understand the physicochemical properties of the copolymers. In the first section, β-CD was reacted with sebacoyl chloride (SCl) and terephthaloyl chloride (TCl) at various mole ratios. Characterization was done using Fourier Transform Infrared Spectroscopy (FT-IR), thermogravimetric analysis (TGA), 1H NMR spectroscopy (1H NMR), elemental analysis (CHN), and nitrogen porosimetry. Copolymers synthesized at mole ratios of β-CD to SCl from 1:1 to 1:3 were hydrolyzed at acidic and basic conditions. Therefore, sorption studies were not done at these ratios. The same occurred for 1:1 to 1:3 TCl copolymers. Sorption studies with PNP at pH 4.6 demonstrated enhanced sorption capacity when comparing with a standard: granular activated carbon (GAC). The sorption capacity, Qm (mmol/g), ordered from largest to smallest is 1:9 SCl>1:9 TCl>1:6 SCl> GAC> 1:6 TCl. Chi-Glu copolymers were synthesized by cross-linking glutaraldehyde with pristine chitosan. A systematic study on the effects reaction conditions have on the sorption capacity of the materials was done. Three conditions were changed: pH, temperature, and mole ratios. Chi-Glu copolymers were synthesized at various chitosan to glutaraldehyde mole ratios (1:400, 1:700, 1:1000). Sufficient time was allowed for the aging process. Characterization was done using TGA, FT-IR, CHN, and nitrogen porosimetry. Sorption study with PNP were done at pH = 7.0 and 9.0. At pH = 7.0 sorption capacity appears to correlate to the quantity of homo-polymerized glutaraldehyde: 1:700>1:1000>1:400. While at pH = 9.0, the sorption capacity is inversely proportional to the degree of crosslinking: 1:400>1:700>1:1000. By increasing the pH at the shrinkage phase, PNP was weakly bound onto the Chi-Glu copolymer. Varying temperature before gelation caused a decrease in the sorption capacity with PNP. Sorption studies involving carboxylates and NAs were done at pH = 9.0 at ambient temperature using Chi-Glu copolymers (1:400, 1:700, and 1:1000) and chitosan. Three carboxylates were chosen to reflect the diverse components in NAs. Varying degrees of cyclization (Z = 0, -2, -4) and lipophilic surface area were the main criteria for carboxylates. The sorption capacity depended mainly on the lipophilic surface area (LSA) with sorption capacity highest for 2-hexyldecanoic acid (S1) which has the largest LSA and lowest for, trans-4-pentylcyclohexanecarboxylic acid (S2) and dicyclohexylacetic acid (S3). Unfortunately, cross-linking with glutaraldehyde does not enhance sorption as pristine chitosan retained a higher sorption capacity compared to Chi-Glu copolymers. Acros and Fluka NAs were chosen for sorption and no significant sorption was recorded for any copolymers. Problems involving the micellization process can explain the lack of sorption.

Mesoporous silica materials containing microporous cavities provided by covalently bound ¦Â-cyclodextrin (CD ICS) were synthesized by co-condensation of a ¦Â-CD functionalized triethoxy silane (CD ICL) with tetraethyl orthosilicate (TEOS) by using neutral amine surfactants as structure directing agents (SDA). CD ICL was prepared by reacting ¦Â-CD with 3-isocyanatopropyltriethoxysilane. IR spectroscopy of CD ICL showed complete disappearance of isocyanato group at 2270 cm-1. 1H NMR results indicate an average of four isocyanate linkers covalently attached to random hydroxyl substituents of each molecule of ¦Â-CD. <p> Nine different CD ICS materials were synthesized using dodecylamine, tetradecylamine or hexadecylamine with ¦Â-CD (2, 4, and 6 mol %) with respect to TEOS. The incorporation of ¦Â-CD within the mesoporous framework was supported by IR, Raman, MALDI TOF MS, solid state 13C NMR CP-MAS and TGA results. Small angle X-ray diffraction results showed a peak at 2¦È ¡Ö 2.20, supporting the presence of an ordered silica mesostructure framework. For materials with same CD loading, the surface area and pore volume doubled as the surfactant from dodecylamine to hexadecylamine. However, as the CD loading increased from 2% to 6%, the surface area decreases by a factor of ~ 1.5. <p>MALDI TOF mass spectrometry showed two peaks at m/z 1157 a.m.u. and 1173 a.m.u. for [¦Â-CD + Na]+ and [¦Â-CD + K]+ respectively due to desorption of ¦Â-CD from the walls of the silica matrix. The 13C NMR CP MAS results showed 13C signals in the region ¦Ä=60-110 ppm due to the nuclei of ¦Â-CD. CD ICS materials were found to be effective as a sorbent in both gas and aqueous phases, respectively. The sorption capacity (mmol/g) of p-nitrophenol increased from 61% to 84% with an increase of CD loading from 2% to 6% and as the alkyl chain length of the SDA increases from dodecylamine to hexadecylamine. The adsorption isotherm of CH3Cl in the gas phase and that of p-nitrophenol in the aqueous phase at ambient temperature adopts a multilayer model of adsorption.

L'objectif est la mise au point d'une méthodologie de synthèse des nanoparticules d'or en présence du chitosane sous rayonnement permettant l'obtention d'objet de taille homogène et contrôlée. Dans ce but, nous mettrons l'accent sur l'étude des interactions entre les ions Au(III) et le chitosane en solution avant irradiation. En effet, la coordination entre des unités de glucosamine et l'ion Au(III) favorise la réduction de Au(III) en Au(0) et la formation de nanoparticules d'or. Cela est démontré clairement par l'étude de l'influence du pH sur la formation de nanoparticule lors du vieillissement des solutions d'HAuCl4 en présence de chitosane. Ce phénomène a été avance pour expliquer tout au moins partiellement, le mécanisme de la réduction des ions Au(III) en présence du chitosane sous rayonnement. Il s'agissait de définir si le mécanisme de réduction des ions Au(III) en ions Au(0) suivait un processus classique tels qu'il a été décrit dans les travaux de Belloni et de Henglein, ou si la présence de chitosane influe sur ce processus. L'élaboration des nanoparticules d'or en présence du chitosane utilisé comme agent stabilisant a été réalisée sous irradiation par faisceau d'électrons ou par rayonnement gamma. L'influence des paramètres de synthèse (rapport du [GLA]/[Au(III)], conditionnement des échantillons, effet de la dose d'irradiation, effet du débit de dose, rôle d'un piégeur de radicaux ou d'électrons solvatés) a ensuite été évaluée sur les propriétés caractéristiques des solutions de nanoparticules d'or (taille, charge, résonance plasmon de surface). L'activité catalytique des nanoparticules synthétisées a été testée vis-à-vis de la réaction de réduction du 4-nitrophénol en 4-aminophénol par NaBH4.Mots-clés : or, nanoparticules, chitosane, coordination, irradiation, faisceau d'électrons, rayonnement gamma, 4-nitrophénol. / The goal of this work is to develop a methodology for the synthesis of gold nanoparticles in the presence of chitosan under radiation to obtain a homogeneous object and controlled size. To reach this purpose, we will focus on the study of interactions between the ions Au(III) and chitosan in solution before irradiation. Indeed, the coordination between units of glucosamine and Au(III) promotes the reduction of Au(III) to Au(0) and the formation of gold nanoparticles. This is clearly demonstrated by the influence of pH on the formation of nanoparticles upon aging of HAuCl4 solutions in the presence of chitosan. This formulation has been used to explain the mechanism of reduction of Au(III) in the presence of chitosan in radiation. It was to define whether the reduction mechanism of ion Au(III) ions Au(0) followed a conventional process such as those described by the work of Belloni and Henglein, or if the presence of chitosan affects this process. The development of gold nanoparticles in the presence of chitosan used as a stabilizing agent was produced by the electron beam and gamma radiation. The influence of the synthesis parameters (report [GLA]/[Au (III)], sample conditioning, effect of irradiation dose, dose rate effect, role of a radical scavenger) on the characteristic gold nanoparticles was then evaluated (size, charge, surface plasmon resonance). The catalytic activity of these nanoparticles was tested towards the reduction reaction of 4-nitrophenol to 4-aminophenol by NaBH4.Keywords: gold, nanoparticles, chitosan, coordination, irradiation, electron beam, gamma radiation, 4-nitrophenol.

Mechanochemically synthesized cobalt oxide-based particles are employed for the catalytic reduction of 4-nitrophenol (4NP), a toxic water contaminant. This reduction produces 4‑aminophenol (4AP), a less toxic, pharmaceutical precursor for drugs such as paracetamol. The indicated reduction has been completed previously using noble metals and/or catalysts requiring extensive solvent use, and time as part of their preparation. The cost and synthesis of these noble metal catalysts hinders the sustainable broad scale application as an environmental remediation solution. The catalyst synthesis explored in this study utilizes the green chemistry technique of vibratory ball-milling and annealing cobalt oxide-based particles at different temperatures, producing unique agglomerates with differing surface structure and catalytic properties. Additional investigation into the mechanism through temperature, pH, and change in pressure over the reaction is completed. Further analysis shows that these catalysts are efficient for the reduction of 4-amino-3-nitrophenol and 2-amino-5-nitrophenol with unique catalytic rates. Finally, it is found that the application of this reduction in a flow process has potential for use on a broader scale.