This work was concerned with the determination of mass transfer and kinetic parameters of ozone reactions with four organic compounds from different families, namely reactive dye RO16, triclocarban, naphthalene and methanol. In order to understand the mechanisms of ozone reactions with the organic pollutants, a radical scavenger (t-butanol) was used and the pH was varied from 2 to 9. Ozone solubility (CAL*) is an important parameter that affects both mass transfer rates and chemical reaction kinetics. In order to determine accurate values of the CAL* in the current work, a set of experiments were devised and a correlation between CAL* and the gas phase ozone concentration of the form CAL*(mol/L) = 0.0456 CO3 (g/m3 NTP) was obtained at 20°C. This work has also revealed that t-butanol did not only inhibit hydroxyl radical reactions but also increased mass transfer due to it increasing the specific surface area (aL). Values of the aL were determined to be 2.7 and 3.5 m2/m3 in the absence and presence of t-butanol respectively. It was noticed that the volumetric mass transfer coefficient (kLa) has increased following the addition of t-butanol. Ozone decomposition was studied at pH values of 2 to 9 in a 500 mL reactor initially saturated with ozone. Ozone decomposition was found to follow a second order reaction at pH values less than 7 whilst it was first order at pH 9. When the t-butanol was added, the decomposition of ozone progressed at a lower reaction order of 1.5 for pH values less than 7 and at the same order without t-butanol at pH 9. Ozone decomposition was found significant at high pHs due to high hydroxide ion concentration, which promotes ozone decomposition at high pHs. The reaction rate constant (k) of RO16 ozonation in the absence of t-butanol was determined. The result suggests that RO16 degradation occurs solely by molecular ozone and indirect reactions by radicals are insignificant. The chemical reaction of triclocarban with ozone was found to follow second order reaction kinetics. The degradation of naphthalene using the liquid/gas-ozone (LGO) system was studied. This result showed that hydroxyl radicals seemed to have limited effect on naphthalene degradation which was also observed when a radical scavenger (t-butanol) was used. Reaction rate constants were calculated and were found around 100 times higher than values reported in the literature due to differences in experimental conditions. From the results of the experimental investigation on the degradation of methanol by ozone it was found that the rate constant (k) of the degradation reaction increased at pH 9. The reaction stoichiometry was found to have a value of 1 mol/mol. The two steps of the liquid/solid-ozone (LSO) system were studied on beds of silica gel and a zeolitic material (D915) and the ozone adsorption process was modeled and found that particle rate controls ozone adsorption step but liquid rate controls the water treatment step. Ozone desorption with pure deionised water was studied. The water flow rate was found to accelerate the desorption rates but pH was found to decrease the desorption rates. In contrast, the effect of pH was insignificant in the presence of t-butanol. Determination of the adsorption isotherms for RO16, naphthalene and methanol revealed that RO16 did not exhibit adsorption on silica gel, but both naphthalene and methanol showed adsorption on D915 described by Langmuir model.

No description available.

Detection and identification of pesticide residues on objects of cultural heritage is a serious and urgent challenge that currently faces many museums, Native American communities, and private collections worldwide. Organic artifact materials, such as wood, animal hide, basketry, textiles, paper, horn and bone, have traditionally been treated with pesticides to eradicate and prevent infestation by insects, rodents, and mold. These poisonous substances can persist for years in the controlled environment of a museum storeroom and present a potential poisoning risk to people who come in contact with the objects. Surface-enhanced Raman spectroscopy (SERS) has the potential to detect volatile organic pesticides in this context. The technique can overcome the insensitivity of normal Raman spectroscopy and fluorescence interference, and make possible detection of many organic compounds in parts per million concentration. This investigation is aimed at evaluating SERS for the detection and identification of volatiles in museums, with emphasis on naphthalene vapor. The potential of several SERS-active materials; Tollens mirrors, gold film over nanosphere arrays, citrate-stabilized colloidal silver, and nanoporous gold; to detect Rhodamine B and naphthalene is investigated. The research also highlights the mechanisms that underlie SERS, and the relationship between substrate nanostructure and SERS performance.

The interest in biosensors can be attributed to the first described enzyme containing sensor used to detect levels of glucose in 1962. Although research into biosensors was initially slow to pick up, the field has become increasingly popular and research has been widespread for the last 20 years. The continuing research into biosensors is crucial as this will improve current devices to become smaller, faster and more economical and yield new biosensors. This thesis is mostly concerned with the development of an integral component of a biosensor, the redox mediator. Complexes of ruthenium incorporating electron rich sulfur-donor ligands such as naphthalenedithiol should possess interesting redox qualities which could be used to produce better mediators. A second area covered in this thesis is in the structural studies of a series of iridium and rhodium complexes. Two classes of ruthenium complexes with sulfur-donor ligands have been prepared. The first class incorporates the ruthenium bis-bipyridine moiety while the second contains pentamethylcyclopentadienyl ruthenium. Most complexes synthesised exhibited reversible oxidation waves in the region of -0.1 to 0.2 V vs. Ag/Ag⁺. Their possible use as redox mediators was hindered by several factors, particularly difficulties in purification. They also exhibited oxygen sensitivity and low stability when in solution.The second area covered in this thesis is to further understand the bonding of the ligands used in the above study. A series of pentamethylcyclopentadienyl iridium and rhodium complexes were synthesised with three different dithiolato ligands. Two of the three ligands studies produced structures that included more than one metal centre leading to straining of the ligand. In order to study the monomeric form, the clusters were opened with a neutral phosphine ligand. Both the Ir…S and Rh…S bond lengths of all the complexes were within expected parameters.

The family of polycyclic aromatic hydrocarbons naphthalene, acenaphthene and acenaphthylene, containing rigid organic backbones, allow the study of non-bonded intramolecular interactions. Due to the rigid framework, heteroatoms that are substituted at the peri-positions (positions 1- and 8- of the naphthalene ring and positions 5- and 6- of the acenaphthene and acenaphthylene rings) are forced to occupy space that is closer than the sum of their van der Waals radii, resulting in severe steric strain and unique interactions. In spite of this, a vast amount of peri-substituted naphthalenes have been prepared, however acenaphthene and acenaphthylene compounds have received much less attention. Preparation of these sterically crowded systems is possible because of the backbones ability to relieve strain as a result of both attractive and repulsive interactions. Attractive interactions relax the backbone via formation of weak or strong bonds between the substituents. Alternatively, repulsive interactions can result in the deformation of the backbone away from its natural geometry by buckling the ring system and causing the peri-bonds to distort in-plane and out-of-plane. Peri-substituted systems can also ease strain by forming compounds with bridging atoms or through bidentate coordination to form metal complexes with, for example, metal bis(phosphine) or bis(thiolate) moieties. The competition between attractive and repulsive forces, the method by which peri-substituted compounds relieve steric strain, is investigated in this thesis using a variety of different peri-moieties and the aforementioned organic backbones. Chapter 2 initially focuses on the formation of a series of platinum bis(phosphine) complexes, constructed from corresponding peri-substituted naphthalenes, 1,8-naphthosultone and 1,8-naphthosultam, the chemistry of which is outlined in Chapter 1. A corresponding study of platinum bis(phosphine) complexes, constructed from analogous 5,6-dihydroacenaphtho[5,6-cd]-1,2-dithiole and 5,6-dihydroacenaphtho[5,6-cd]-1,2-diselenole bidentate ligands is provided in Chapter 6. The chemistry of peri-substituted naphthalenes is well documented and a number of reviews have been written on this subject. Chapter 3, meanwhile, reviews the chemistry of related acenaphthene and acenaphthylenes which have seen increasing use in the literature over the last few years. Chapter 4 investigates the relationship between repulsive and attractive interactions that occur between the peri-substituents in a series of bis-chalcogen, mixed chalcogen-chalcogen and mixed halogen-chalcogen acenaphthylenes. By comparison with their known naphthalene and acenaphthene counterparts, the effect the rigid aromatic ring system has on the molecular geometry is examined. Finally, Chapter 5 looks at a series of acenaphthene and acenaphthylene compounds containing ArTe peri-substituents and explores how repulsive and attractive interactions affect molecular conformation and Te•••Te spin-spin coupling constants.

Characterizing the interactions of solvent molecules with ions is fundamental in understanding the thermodynamics of solution chemistry. These interactions are difficult to observe directly in solution because the number of solvent molecules far exceed that of ions. This lend the gas phase to be the ideal medium in the study ion-solvent interactions on a molecular level. Ionized polycyclic aromatic hydrocarbon (PAH) molecules can readily form hydrogen bonds with neutral solvent molecules in aqueous and interstellar medium. Previous research has been done for stepwise solvation of small molecules such as benzene+, pyridine, and phenylacetylene. The similarity in these results show that these organic ions can be considered prototypical model systems for aromatic ion-neutral solvent interactions. The goal of this dissertation is to demonstrate that naphthalene can act as a prototypical model of PAH ions for ion-solvent interactions. Two types of experiments are considered throughout this dissertation using ion mobility mass spectrometry: (1) ion-neutral equilibrium thermochemistry and (2) mobility measurements. For thermochemistry experiments, the naphthalene radical cation was injected into the drift cell containing helium and/or neutral solvent vapor and the enthalpy and entropy changes were measured by varying the drift cell temperature and measuring the equilibrium constants. The results of these studies showed that small polar molecules bind to naphthalene with similar energy based on the measured by the enthalpy changes. Unsaturated aliphatic molecules behave similarly, but with much lower binding energy. Aromatic ions tend to bind to the naphthalene with lower binding energy than that observed with the benzene ion. The results for small polar molecules were compared to similar studies using the phenyl cation. The second series of experiments required the coexpansion of the naphthalene and benzene or pyridine. Injecting theses dimers into the drift cell allowed the measurement of reduced mobility on the dimers at a series of temperatures. These were used to calculate the average collision cross section and thus give insight in to the structure of these aromatic dimers. Structures were determined by comparing these results to those predicted by DFT calculations.

As diimidas naftálicas simétricas têm sido vastamente estudadas devido suas propriedades químicas, ópticas, e eletrônicas. A possibilidade de modular suas propriedades com a substituição de grupos diversos na formação da imida, viabiliza aplicações em dispositivos eletrônicos, conversão de energia e produção de redes de coordenação metalo-orgânicas. Neste trabalho sintetizou-se uma série de 5 diimidas naftálicas (NDIs) simétricas com substituintes aromáticos. Foram analisadas as características espectroscópicas e eletrônicas com obtenção dos valores de band-gap óptico através de ensaios de voltametria cíclica e cálculos teóricos (DFT), mostrando a influência dos substituintes nas propriedades eletrônicas. Estas moléculas apresentam indícios de agregação em determinados solventes tornando possível a produção de filmes finos. As NDIs produzidas foram intercaladas em uma matriz inorgânica lamelar, o pentóxido de vanádio amorfo, e melhorando consideravelmente, via de regra, a capacidade específica de carga quando analisados em sistemas trocadores de íon lítio, aplicados geralmente em cátodos de bateria, com valores da ordem de 190 mA.h.g-1 (sob 100 uA, variação de E +1,2V à -1,2V). É provavelmente um dos primeiros trabalhos a utilizar NDIs em sistemas mistos de matrizes inorgânicas aplicados em trocadores de íons. Algumas apresentam potencial para dispositivos de conversão de luz em eletricidade. / Symmetric naphthalic diimides have been extensively studied due to their chemical, optical, and electronic properties. The possibility of modulating their properties by substitution with several groups in the formation of imides allows diverse applications in electronic devices, energy conversion, production of metallo-organic frameworks (MOFs). In this thesis, a series of 5 symmetrical aromatic-substituted naphthalic diimides (NDIs) were sinthesized. We have studied their optical and electronic characteristics obtaining optical band-gap with cyclic voltammetry tests and theoretical calculations (DFT), showing the influence of substituent in the electronic properties. Some of these imides may aggregate in certain solvents allowing this way the production thin films. The NDIs were intercalated in the inorganic intercalation matrix of amorphous vanadium pentoxide, and showed generally considerable improvement in the specific charge capacity when used in lithium ion exchange systems, that are usually applied in battery cathodes, reaching values of the order of 190 mA.h.g-1 (under 100 uA, E variation of + 1.2V to -1.2V). This is probably one of the first works using NDIs in mixed systems to applied inorganic matrices as ion exchangers. Some of them may be used for light conversion to electricity devices.

A thesis submitted in fulfilment of the requirements for the degree Magister Technologiae (Chemistry) in the Faculty of Applied Sciences, Department of Chemistry, Cape Peninsula University of Technology, 2008 / Green et al. attempted to synthesize linear naphthopyranquinones from a naphthyl dioxolane using a TiCl4 as a catalyst. They managed to synthesise an angular naphthopyran as well as a linear naphthopyran in low yield. They showed that reducing the steric strain at position 1 of the naphthyl dioxolane afforded a low percentage yield of the linear naphthopyran plus an angular one. This thesis describes the synthesis of linear naphthopyrans with an improved percentage yield using TiCl4 as a catalyst. This was achieved by placing a OMe group of less steric hinderance at position 1 and a Br atom at position 4 of a naphthyl dioxolane. The OMe group at position 1 was to allow isomerisation to occur at position 2, and the Br atom was to inhibit isomerisation at position 4, thereby inhibiting the formation of the angular naphthopyran.

Nitrogen is known to be a limiting factor in polluted environments, however many studies overlook the potential role for nitrogen to significantly influence the removal rate and efficiency with which microorganisms can degrade aromatic hydrocarbons. In this study, inoculated and uninoculated aerated soil microcosms containing different s-triazines were examined for their ability to efficiently and rapidly treat contaminated soils containing naphthalene, nitrobenzene, and toluene (NNT), via a microbial consortium consisting of Pseudomonas, Rhodococcus, and Aeromonas. After an experimental period of 14 days, greater than 90% degradation of NNT supplemented with different s-triazines, at concentrations of 1000-3000 ppm was observed. A difference in the degradation of NNT was seen in inoculated box reactors supplemented with cyanuric acid, melamine, and atrazine in comparison to uninoculated box reactors. Combined usage of 16s rDNA and 16s rRNA analysis was then applied to study the bacterial communities, and determine the abundance and survival of inoculated strains within box reactors contaminated with NNT. The bacterial diversity within clone libraries obtained illustrated a dominance of proteobacteria and gram positive bacteria. Analysis from clone libraries also showed that inoculated strains did survive within each condition, but were not the most predominant members present in the communities. This research shows that significant removal of NNT can be achieved in two weeks with the supplementation of one of the s-triazines. However, differences in degradation and the microbial populations present within contaminated communities will be seen depending on which nitrogen sources are used and whether or not environments are bioaugmented or not.

Catalytic naphthalene hydrogenation to tetralin in water/hydrocarbon emulsions with simultaneous water gas shift as the hydrogen source was performed in a 300 ml batch autoclave as a model for aromatic hydrogenation in water/bitumen emulsions. The catalyst utilized was an unsupported and dispersed type based on molybdenum sulfide (MoS2). Distinguishing the fate of hydrogen from water as opposed to molecular hydrogen in hydrogenation and water gas shift was accomplished by utilizing deuterium oxide (D2O) with NMR spectroscopy. The use of D2O allowed determination of isotope effects when compared with H2O. Diffuse Reflectance Infrared Fourier Transform Spectroscopy was performed to observe CO adsorption on the MoS2 sulfide surface. Ruthenium was tested as a potential candidate to enhance the activity of the Mo catalyst. Iron, nickel and vanadium were utilized in combination with molybdenum to test promotional/inhibitive activity during naphthalene hydrogenation and water gas shift since Ni and V are found in significant quantities in real bitumen feed. Finally, a multifactorial experiment was performed to test the hydrogenation and water gas shift activity of a binary VNiMo-sulfide catalyst towards H2S partial pressure, temperature and H2 versus CO atmospheres. Deuterium from D2O was incorporated into both saturated and aromatic hydrogen positions in tetralin products. Calculation of a Hydrogenation Index and Exchange Index indicated the extent of H-exchange is greater than hydrogenation. Exchange between D2O and organic products was enhanced with the MoS2 catalyst under H2 or CO compared to N2. A kinetically measured isotope effect of 1.58 was in agreement with a quasi-equilibrium thermodynamic isotope effect for O-H dissociations measured in the literature. A true kinetic isotope effect may be masked by transient surface concentrations occurring under batch conditions. Two strong vibrational bands associated with adsorbed CO were observed over MoS2 above 160 °C. Activation of the MoS2 surface with CO produces COS, suggesting an analgous mechanism to the production of H2S during reduction in H2. In the presence of H2S, Ru displayed low catalytic activity for both water gas shift and naphthalene hydrogenation, attributed to incomplete sulfidation to active RuS2. FeMo and VMo exhibited lower hydrogenation activity than Mo, but the water gas shift activity of VMo was high. A ternary VNiMo displayed lower hydrogenation activity than NiMo and Mo but was higher than VMo, implying Ni could offset the inhibition caused by V. Recycle of V and Ni rich asphaltene residues in catalytic slurry upgrading may therefore be feasible. An analysis of the effect of H2S pressure, temperature and type of reduction gas (CO vs. H¬2) concluded that temperature had the greatest positive effect on rate, followed by a small interaction effect of temperature/gas type and PH2S/gas type. The proximity to equilibrium conversions in WGS limited the analysis, while equilibrium limited the conversion of naphthalene at 380 °C in the batch reactor.