The rate of removal of benzene, toluene, ethylbenzene and the xylene isomers (BTEX) from contaminated groundwater is needed to design remediation processes. Benzylsuccinic acid (BSA) and methyl-benzylsuccinic acid (methyl BSA) are unambiguous metabolites of anaerobic BTEX biodegradation. An analytical method for quantitative determination of BSA in groundwater samples was developed. Samples containing BSA and methyl BSA were extracted onto 0.5 g of styrene-divinylbenzene, eluted with ethyl acetate, and methylated with diazomethane. Gas chromatography coupled to mass spectrometry with electron impact ionization was used for separation and detection. The recovery from spiked 1 L groundwater samples was 88 to 100 %. The precision of the method, indicated by the relative standard error was ± 4% with a method detection limit of 0.2 μg/L. The method was then used to analyze samples from single-well push-pull tests conducted by injecting deuterated toluene and xylene into BTEX-contaminated wells in order to demonstrate in-situ biodegradation. Unambiguous evidence for deuterated toluene and xylene biodegradation was obtained with the observation of deuterated BSA and methyl BSA coupled with the utilization of nitrate presumably due to denitrification as terminal-electron-accepting process. Minimum first-order degradation rates for deuterated toluene estimated from formation of BSA were 0.0004 to 0.001 day⁻¹. Rates of methyl BSA formation were not calculated because methyl BSA, although detected, was not above the quantitation limit. Removal rates of deuterated toluene and o-xylene were not directly measurable because the rates were too low to measure significant changes in parent compound concentrations. Wells for which the formation of deuterated BSA and methyl BSA were observed had lower relative concentrations of toluene and xylenes relative to total BTEX than wells for which no deuterated BSA and methyl BSA were observed. Retardation factors for injected deuterated toluene and background toluene of 2 and 14, respectively, were obtained from push-pull tests conducted to determine toluene transport properties. Differences in retardation factors for injected and background toluene indicate differences between injected and background solute transport and is a topic that requires further study. / Graduation date: 2002

Volatile organic compounds (VOCs) can be considered as a major source of air pollution, and in many cases, legislation has already been introduced to reduce their emissions. O-xylene, one of VOCs, is widely used in industry as solvent and also the raw material of o-Phthalic anhydride (PA). The subjects of this research are divided into four parts, they are screening activity of catalysts, incineration efficiency with various operation parameters, physical properties of catalysts and kinetic model derivation. In screening activity of catalysts, Four kinds of metal ions (Cu, Mn, Zn, Fe; the molar ratio of metal/Fe is 1/2), three different temperature (70¢J, 80¢J, 90¢J) and pH (9, 10, 11) were the parameters of FP to manufactured 36 ferrospinel catalysts. Under the same reaction conditions (o-xylene conc.=1600 ppm, GHSV=71150 hr-1, O2=21%, temperature=298K~673K), it¡¦s found that the most efficient catalyst was Cu/Fe ferrospinel and its synthesis condition was pH at 9 and temperature at 90¢J. The operation parameters to determine incineration efficiency were temperature at 373K ~ 673K, inlet o-xylene concentration at 600 ~ 1600 ppm, GHSV at 47450 ~ 71150 hr-1, O2 concentration at 21 ~ 40%. The results showed that the conversion was proportional to the increase of inlet o-xylene concentration, temperature and inlet oxygen content and was inverse proportional to the increase of GHSV. To realize the physical properties of catalysts, XRD, SEM and EDS were applied. The results indicated that there was no physical difference between fresh and used catalysts. Besides, two kinetic models, Power rate law and Mars-Van Krevelen model were used to demonstrate the decomposition of o-xylene. It¡¦s discovered that Power rate law was more reasonable to illustrate the catalytic o-xylene oxidation. Further, the reaction rate was increased with the increase of inlet o-xylene and oxygen concentration and reaction temperature.

Thesis (M.S.)--University of Missouri--Rolla, 2007. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed November 16, 2007) Includes bibliographical references (p. 85-89).

Thesis (M. App. Sc.)--Carleton University, 2002. / Includes bibliographical references (p. 166-174). Also available in electronic format on the Internet.

Este trabalho de pesquisa foi elaborado com o objetivo de apresentar os resultados da recuperação e reciclagem de xileno, gerado em laboratórios de análises clínicas. É importante salientar a importância de um programa de gestão e gerenciamento de resíduos químicos, principalmente em instituições de ensino e pesquisa, de forma a contribuir para a preservação do ambiente e possibilitar a formação de profissionais conscientes, acostumados à práticas corretas de gestão e gerenciamento de resíduos químicos. A recuperação do resíduos de xileno foi feita por meio da técnica de destilação fracionada. Para a verificação da eficiência da recuperação do xileno, foram analisadas amostras do resíduo de xileno, do xileno recuperado e do xileno padrão, com o propósito de comparar os resultados obtidos destas amostras por meio das análises de Espectrofotometria de ultravioleta visível, (UVVis), Refratometria, Cromatografia Gasosa (CG) e Cromatografia Gasosa acoplada à Espectrometria de Massas (CG-EM). Os resultados desta pesquisa confirmam a eficiência da recuperação do resíduo de xileno, possibilitando que este retorne ao processo produtivo ou gerador, na forma de produto, refazendo assim, o ciclo por completo. A recuperação do resíduo do xileno e sua reciclagem traz benefícios ambientais e econômicos. / This research was elaborated with the objectives to present the results of recovery and recycling of xylene, generated in clinical analyses laboratories. It is essential to point out the importance of management and chemical waste management program, especially in education and research institutions, contributing to environment preservation and to making possible the qualification of conscientious professionals, used with correct practices of management and the chemical waste management. The xylene waste was recovered by fractional distillation technique. To verify the efficiency of the xylene recovery it was analyzed samples of waste xylene, recovered xylene and standard xylene, to compare the obtained data of these samples through the ultraviolet-visible Spectrophotometry (UV - Vis), Refractometry, Gas Chromatography (GC) and connected Gas Chromatography to the Spectrometry of Mass (GC-MS) analyses. The results of this work confirmed the efficiency of the xylene recovery, making possible its return to the productive or generator processes as a product, thus completing the entire cycle. The recovery of the xylene waste and its recycling has important ambient and economic benefits.

Benzene, toluene, and xylene are three basic raw materials for the production of most aromatic derivatives such as polyesters, plastics and detergents. Xylenes (p-, m- and o-) have the greatest market demand with an increasing annual rate of 6%. Owing to the availability of surplus toluene and low value of C9 aromatics, the transalkylation process is aimed at the production of more valued products, such as xylenes. Catalyst deactivation is a key challenge in transalkylation process. Using industrially relevant operating parameters, the transalkylation of 1,2,4-trimethylbenzene (TMB) with toluene was studied. The effect of zeolite structure and acidity, increased reaction pressure and temperature, and very low levels of platinum (Pt) impregnation has been investigated over both H-form and Pt-loaded zeolites: Beta, Mordenite (MOR), and Y. A fixed bed reactor was used at WHSV of 5 h-1, 400 oC, and a 50:50 wt. % toluene:TMB ratio with the order of activity after 50 h time-on-stream (TOS) of Y > Beta >> MOR at 1 bar. At elevated pressure (10 bar), all catalysts showed better performance with significant improvement in MOR as pore blockage was reduced and the order of activity was Beta > MOR > Y. With varying the Si/Al ratio for zeolites Beta (Si/Al = 12.5, 75 and 150) and Y (Si/Al = 2.6, 6, 15 and 30), the highest stability and xylenes yield were achieved over zeolite Beta with lowest Si/Al ratio at 41 wt. % conversion and 25 wt. % xylenes yield. In contrast, zeolites Y with Si/Al ratio of 2.6 showed the highest deactivation rate, whereas over Y zeolites with Si/Al = 6-30, the conversion was between 25-30 wt. % and xylenes yield around 11 wt. % after 50 h TOS. Incorporation of Pt (0.08 wt. %) further improved the activity of all catalysts with the highest conversion after 50 h TOS over Beta (62 wt. %) where Beta and MOR yielded similar levels of xylenes (40 wt. %). All catalysts were further optimized by reducing Pt levels whilst maintaining the desired stability and highest xylenes yield. In order to further develop a cost-effective and eco-friendly catalyst, the addition of alumina binder to Pt-Beta and the possibility of simplified regeneration of Beta/Pt-Beta catalyst were investigated. Firstly, the alumina binder reduced the conversion and xylenes yield, however, this reduction was small up to 40 wt. % added alumina binder (where xylenes yield only dropped to 35 wt. %). Secondly, the regeneration process was carried out using H2 only and up to four cycles (30 h TOS per cycle). The Pt-Beta catalyst found to be stable and the activity was fully restored by a hydrogenation process at 500 oC. However, the activity of Beta dropped gradually after each cycle suggesting that the H2 alone at 500 oC was insufficient in removing coke precursors. The drop in activity was attributed to the disappearance of Brà ̧nsted acid sites over the spent Beta catalyst due to the growth of coke molecules trapped in cavities leading to highly polyaromatic molecules blocking those active sites.

Organic/inorganic materials have a high potential to enable major advances in membrane performance. It has previously been impossible to develop polymeric systems with adequate transport properties for xylene purification. Zeolite membranes have been created with the appropriate selectivities; however low productivity, low mechanical durability, and high capital costs have kept these materials from being utilized. So-called mixed matrix hybrid organic/inorganic membranes combine the mechanical durability and cost effectiveness of polymeric membranes with the enhanced performance of zeolitic structures. This project will focus on investigating polymeric and molecular sieve materials for mixed matrix membrane use in xylene isomer separation as a model system. Torlon polyamide-imide has unique properties that should be potentially useful in a mixed matrix composite. Silicalite will be investigated as the dispersed phased given its proven applicability with xylene isomers. The overarching goal is to establish an approach for creation of mixed matrix materials that can be broadly applied to challenging organic separations. This project has three specific goals: (1) characterization of Torlons inherent properties, processing ability, and important transport potential, (2) characterization of zeolite matching properties and the effect of interfacial engineering on these properties, and (3) development of appropriate approaches to combine the sieve and polymer to obtain a hybrid material with properties that match theoretically predicted separation property enhancements relative to the neat polymer. High temperature pervaporation will be used to evaluate material transport properties, as this experimental setup closely mimics the high activity vapor streams found in many industrial xylene processes. The results of this research will be used to develop a protocol for development of future mixed matrix membranes that may be applied to a variety of organic liquid systems.

Organic solvents in varnish can easily cause volatile organic compounds (VOCs) and odorous problems in manufacturing plants of enamel insulated wire. In general, the related process exhaust gases are treated by catalytic incinerators. However, the slight odors in the incinerated exhausts may induce uncomfortable feels to the inhabitants in the vicinity of the plants. Main components of odors are reported to be xylenes and to a lesser extent ketones. This study intended to oxidize the odorous compounds by chemical scrubbing method with either sodium hypochlorite or ozone as an oxidant and hydrogen peroxide as a reducing agent for the elimination of residual chlorine or ozone emitted from the oxidation scrubber. An additional study was the oxidation of aqueous mixed xylenes by sodium hypochlorite. The first part of the study was the chemical oxidation of aqueous xylenes by sodium hypochlorite. Results indicated that more than 95 % of 20 mg/L xylenes could be converted to some oxygenated hydrocarbons with an initial effective chlorine concentration of 180 mg/L at pH 6.5 over a prolonged reaction time of over 120 min. With pH < 3 and a reaction time of 120 min, xylenes could be oxidized to benzene carboxylic acid that precipitated as organic crystalline solids to the reactor bottom. The second part was chemical scrubbing of the odorous gases emitted from the catalytic incinerator. Operation conditions were an effective chlorine concentration of 1,500 mg/L and pH 6.5 for the oxidative scrubbing liquor, and a hydrogen peroxide concentration of 700 mg/L and pH > 12 for the reductive one. Results indicated that on an average, around 59 % of the influent xylenes could be removed, and the scrubbed gas was nearly odorless. 65.0 - 98.5 % of the influent non-aromatic compounds could be removed with trace amounts of chlorinated compounds in the gas were detected. The third one was the treatment of the odorous gases by using ozone as an oxidant and followed by activated carbon adsorption. 18 - 34 mg/m3 of ozone was added to the test gas with initial xylene concentrations of 25 - 55 mg/m3. Results indicated that only around 35 % of the added xylene was removed with ozone contact times of 0.15 - 0.6 min. Although 99.9 % of the residual ozone and odors were removed by the activated carbon, a longer operation time should be tested to verify the performance. Trace amounts of ring cleavage precursors of 2.4-dimethylphenol and ring cleavage products were found in the ozonized gas.

Microcosm studies were conducted beginning with three xylene isomers: ortho-xylene, meta-xylene and para-xylene; and continued with the four mononitroxylene (MNX) isomers, culminating with testing ten dinitroxylene (DNX) isomers. Soil samples were obtained from a historically contaminated site with high levels of dinitrotoluene (DNT), trinitrotoluene (TNT) and dinitroxylene (DNX) and used as the inoculum for microcosm tests. The microcosm method of different isomers was based on the previous work on biodegradation of nitrotoluene. As it was demonstrated previously that 2,4-DNT degrading bacteria were present at the site, it was hypothesized that these may be capable of transforming or cometabolizing some of DNX isomers. Thus, DNX cometabolism studies were conducted in the presence of 2,4-DNT degrading bacteria. The presence of xylene and 2,4-DNT degrading was confirmed in this thesis. Meanwhile, several MNX and DNX isomers showed degradability in microcosm studies. Cometabolism studies showed that four DNX isomers could be cometabolized by 2,4-DNT enrichment.

Primary immune-mediated hemolytic anemia (IMHA) is an important cause of serious morbidity and mortality in dogs. Despite numerous studies examining the demographics, treatment options, and prognostic indicators of disease, the mechanisms that underlie immune dysregulation remain poorly understood. The purpose of this study was to directly identify unique erythrocyte membrane antigens in dogs diagnosed with primary IMHA. Blood samples were obtained from dogs presented to the Ontario Veterinary College Teaching Hospital with primary IMHA prior to treatment, and also from control dogs (healthy dogs and dogs with non-immunologic anemia). Antibodies bound to erythrocyte membranes were eluted using xylene. Immunoblots using patient eluates reacted against pooled canine erythrocyte lysates, and autologous patient plasma reacted against xylene eluates, were performed. These results were compared to results of similar experiments using samples from control dogs. Bands appearing in patient but not control samples were considered potential autoantigens, and were submitted for identification by liquid chromatography followed by tandem mass spectrometry. Samples from 13 dogs with primary IMHA, 4 dogs with non-immunologic anemia, and 2 healthy dogs, were analyzed. Immunoblotting confirmed the presence of immunoglobulin in eluates from all dogs. Semi-quantitatively, eluates from IMHA patients contained more immunoglobulin than those of control dogs. Mass spectrometry identified complement C3 in patient but not in control dog samples. Additional peptides identified by mass spectrometry in patient but not control dog samples included peroxiredoxin 2 and calpain. The former comprises a cytosolic hydrogen peroxide scavenger, and has been associated with erythrocyte membranes under oxidative stress conditions inducing spherocytosis. Calpain is a calcium-dependent protease that may become activated with oxidative stress and induce erythrocyte apoptosis. These findings suggest that oxidative stress and apoptosis contribute to the pathogenesis of canine IMHA. / OVC Pet Trust Fund, American Kennel Club Canine Health Foundation