Episódios de contaminação envolvendo hidrocarbonetos de petróleo são relatados com bastante freqüência, principalmente em função dos acidentes envolvendo transporte e estocagem de combustíveis, dentre os quais se destacam o benzeno, tolueno, etilbenzeno e xileno (BTEX). Assim, não é surpreendente o grande número de trabalhos, atualmente disponíveis, relacionados à remediação de águas subterrâneas. Entretanto, é conhecido que a total mineralização de benzeno, na maioria das tecnologias utilizadas para remediação de solos e águas subterrâneas, não ocorre totalmente podendo formar compostos fenólicos altamente tóxicos. Por este motivo, este trabalho teve por finalidade a análise dos subprodutos formados a partir da degradação do benzeno, que são eles: hidroquinona, resorcinol, catecol, fenol, p-benzoquinona. Para este propósito, os compostos fenólicos formados foram medidos utilizando um eletrodo de carbono vítreo modificado com filme de nanotubos de carbono e ftalocianinas metalicas. Os compostos fenólicos também foram analisados por cromatografia liquida de alta eficiência com detector espectrofotométrico, espectrometria no UV/Visível. Os sensores eletroquímicos propostos mostraram-se altamente eletrocatalíticos e sensíveis na determinação dos derivados da oxidação do benzeno, obtendo-se um limite de detecção de 4,54 μmol L-1 para a hidroquinona, de 1,63 μmol L-1 para o resorcinol, 0,14 μmol L-1 para o catecol, 4,19 μmol L-1 para o fenol e 1,78 μmol L-1 para a p-benzoquinona. Observa-se que existem algumas diferenças nos limites de detecção para cada composto fenólico estudado e que o eletrodo GC/MWCNT/CoPc apresentou menores limites de detecção para o catecol, resorcinol e p-benzoquinona podendo analisar predominantemente esses compostos fenólicos a partir da eletro-oxidação do benzeno. A metodologia proposta comparada com os métodos oficiais de análise e foi observado que os sensores atingem os limites mínimos necessários de detecção, demonstrando que sensores eletroquímicos baseados em CNTs tornam-se uma alternativa no desenvolvimento de metodologias altamente sensíveis, rápidas e de baixo custo. / Contamination episodes involving petroleum hydrocarbons are reported quite frequently, mainly because of accidents involving transportation and storage of fuels, among which stand out as benzene, toluene, ethylbenzene and xylene (BTEX). Thus, it is not surprising the large number of papers currently available relating to remediation of groundwater. However, it is known that the complete mineralization of benzene, most of the technologies used for remediation of soil and groundwater, it doesn\'t occur and it can form highly toxic phenolic compounds. For this reason, this paper aims to analyze the products formed from the degradation of benzene, which are: hydroquinone, resorcinol, catechol, phenol, p-benzoquinone. For this purpose, the phenolic compounds formed were measured using a glassy carbon electrode modified with a film of carbon nanotubes and metallic phthalocyanines. Phenolic compounds were also analyzed by high performance liquid chromatography with UV detection, spectroscopy in UV / Visible. The proposed electrochemical sensors were highly sensitive and the electrocatalytic determination of the oxidation of benzene derivatives, obtaining a detection limit of 4.54 μmol L-1 for hydroquinone, 1.63 μmol L-1 for resorcinol , 0.14 μmol L-1 for catechol, 4.19 μmol L-1 for phenol and 1.78 μmol L-1 for p-benzoquinone. It is observed that there are some differences in detection limits for each phenolic compound studied and the electrode GC/MWCNT/CoPc had lower detection limits for catechol, resorcinol and p-benzoquinone can analyze these phenolic compounds predominantly from the electro- oxidation of benzene. The proposed methodology was compared with the official methods of analysis and it was observed that the sensors reach the required minimum limits of detection, demonstrating that electrochemical sensors based on CNTs become an alternative for the development of high sensitivity, rapid and low-cost. methodologies.

by Chiu Peng Fai. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 82-87). / Abstracts in English and Chinese. / Table of Contents --- p.i / Acknowledgements --- p.iv / Abbreviations --- p.v / Abstract --- p.vi / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Definition of Carbon Hydrogen Bond Activation (CHA) by Transition Metal Comple --- p.1 x / Chapter 1.2 --- The Importance of Alkane CHA and its Potential Use --- p.1 / Chapter 1.3 --- Difficulties in Alkane CHA --- p.3 / Chapter 1.4 --- The Use of Transition Metal Complexes in CHA Reactions --- p.4 / Chapter 1.5 --- Classification of CHA Reactions --- p.6 / Chapter 1.6 --- The Importance of Toluene and Benzene CHA --- p.11 / Chapter 1.7 --- Difficulties and Challenges in CHA of Toluene --- p.11 / Chapter 1.8 --- Selectivity Control and Rate Promotion --- p.12 / Chapter 1.9 --- Structural Features of Rhodium Porphyrins --- p.17 / Chapter 1.10 --- CHA by Rhodium Porphyrins --- p.19 / Chapter 1.11 --- Objective of Work --- p.21 / Chapter Chapter 2 --- CHA Reactions of Toluenes by Rhodium Porphyrin Chlorides / Chapter 2.1 --- Synthesis of Rhodium Porphyrin Chlorides --- p.22 / Chapter 2.2 --- Temperature Effects of CHA in Toluene --- p.22 / Chapter 2.3 --- Inter and Intra Molecular Exchange of Alkyl Rhodium Porphyrin Complexes --- p.24 / Chapter 2.4 --- Electronic Effect of Rhodium Porphyrin Chlorides --- p.24 / Chapter 2.5 --- Electronic Effect of Toluene Towards CHA --- p.25 / Chapter 2.6 --- X-Ray Data --- p.26 / Chapter 2.7 --- Mechanistic Studies --- p.30 / Chapter 2.8 --- Ligand and Base Effects --- p.32 / Chapter 2.9 --- Optimization of Reaction Conditions --- p.35 / Chapter 2.10 --- Electronic Effect of Toluenes --- p.36 / Chapter 2.11 --- Concentraction Effects of Toluenes (Reactions in Benzene) --- p.38 / Chapter 2.12 --- Porphyrin Effects in CHA of Toluene --- p.39 / Chapter 2.13 --- Mechanistic Studies --- p.40 / Chapter 2.14 --- Conclusion --- p.42 / Chapter 2.15 --- Reaction between Rh(ttp)Me and Toluenes --- p.42 / Chapter 2.16 --- Selective Benzylic CHA --- p.42 / Chapter 2.17 --- Isotope Effect --- p.44 / Chapter 2.18 --- Discussion --- p.44 / Chapter 2.19 --- Exploratory Studies of Other Base-Promoted Reactions --- p.45 / Chapter 2.20 --- Benzylic CHA and Aromatic Carbon Halogen Bond Activation (CXA) Reactions --- p.45 / Chapter 2.21 --- Base-Enhanced Aromatic CXA --- p.48 / Chapter 2.22 --- X-Ray Data --- p.49 / Chapter 2.23 --- Base-Enhanced Benzylic Carbon Carbon Bond Activation (CCA) Reactions --- p.51 / Chapter 2.24 --- Summary --- p.52 / Chapter Chapter 3 --- Experimental Sections --- p.53 / References --- p.82 / Appendix I Crystal Data and Processing Parameters --- p.88 / Appendix II List of Spectra --- p.123 / Spectra --- p.125

Thesis (Sc.D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Bibliography: leaves 936-960. / by James D. Bittner. / Sc.D.

Yim Wai-leung. / "September 2002." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (p. 117-123). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Episódios de contaminação envolvendo hidrocarbonetos de petróleo são relatados com bastante freqüência, principalmente em função dos acidentes envolvendo transporte e estocagem de combustíveis, dentre os quais se destacam o benzeno, tolueno, etilbenzeno e xileno (BTEX). Assim, não é surpreendente o grande número de trabalhos, atualmente disponíveis, relacionados à remediação de águas subterrâneas. Entretanto, é conhecido que a total mineralização de benzeno, na maioria das tecnologias utilizadas para remediação de solos e águas subterrâneas, não ocorre totalmente podendo formar compostos fenólicos altamente tóxicos. Por este motivo, este trabalho teve por finalidade a análise dos subprodutos formados a partir da degradação do benzeno, que são eles: hidroquinona, resorcinol, catecol, fenol, p-benzoquinona. Para este propósito, os compostos fenólicos formados foram medidos utilizando um eletrodo de carbono vítreo modificado com filme de nanotubos de carbono e ftalocianinas metalicas. Os compostos fenólicos também foram analisados por cromatografia liquida de alta eficiência com detector espectrofotométrico, espectrometria no UV/Visível. Os sensores eletroquímicos propostos mostraram-se altamente eletrocatalíticos e sensíveis na determinação dos derivados da oxidação do benzeno, obtendo-se um limite de detecção de 4,54 μmol L-1 para a hidroquinona, de 1,63 μmol L-1 para o resorcinol, 0,14 μmol L-1 para o catecol, 4,19 μmol L-1 para o fenol e 1,78 μmol L-1 para a p-benzoquinona. Observa-se que existem algumas diferenças nos limites de detecção para cada composto fenólico estudado e que o eletrodo GC/MWCNT/CoPc apresentou menores limites de detecção para o catecol, resorcinol e p-benzoquinona podendo analisar predominantemente esses compostos fenólicos a partir da eletro-oxidação do benzeno. A metodologia proposta comparada com os métodos oficiais de análise e foi observado que os sensores atingem os limites mínimos necessários de detecção, demonstrando que sensores eletroquímicos baseados em CNTs tornam-se uma alternativa no desenvolvimento de metodologias altamente sensíveis, rápidas e de baixo custo. / Contamination episodes involving petroleum hydrocarbons are reported quite frequently, mainly because of accidents involving transportation and storage of fuels, among which stand out as benzene, toluene, ethylbenzene and xylene (BTEX). Thus, it is not surprising the large number of papers currently available relating to remediation of groundwater. However, it is known that the complete mineralization of benzene, most of the technologies used for remediation of soil and groundwater, it doesn\'t occur and it can form highly toxic phenolic compounds. For this reason, this paper aims to analyze the products formed from the degradation of benzene, which are: hydroquinone, resorcinol, catechol, phenol, p-benzoquinone. For this purpose, the phenolic compounds formed were measured using a glassy carbon electrode modified with a film of carbon nanotubes and metallic phthalocyanines. Phenolic compounds were also analyzed by high performance liquid chromatography with UV detection, spectroscopy in UV / Visible. The proposed electrochemical sensors were highly sensitive and the electrocatalytic determination of the oxidation of benzene derivatives, obtaining a detection limit of 4.54 μmol L-1 for hydroquinone, 1.63 μmol L-1 for resorcinol , 0.14 μmol L-1 for catechol, 4.19 μmol L-1 for phenol and 1.78 μmol L-1 for p-benzoquinone. It is observed that there are some differences in detection limits for each phenolic compound studied and the electrode GC/MWCNT/CoPc had lower detection limits for catechol, resorcinol and p-benzoquinone can analyze these phenolic compounds predominantly from the electro- oxidation of benzene. The proposed methodology was compared with the official methods of analysis and it was observed that the sensors reach the required minimum limits of detection, demonstrating that electrochemical sensors based on CNTs become an alternative for the development of high sensitivity, rapid and low-cost. methodologies.

Use of electronic cigarettes (e-cigarettes) is rapidly growing around the world. E-cigarettes are commonly used as an alternative nicotine delivery system, and have been advocated as generating lower levels of harmful chemicals compared to conventional cigarettes. Cigarette smoke-like aerosols are generated when e-cigarettes heat e-liquids. The main components of e-cigarette liquids are propylene glycol (PG) and glycerol (GL) in a varying ratio, plus nicotine and flavor chemicals. Both PG and GL are considered safe to ingest in foods and beverages, but the toxicity of these chemicals in aerosols is unknown. Current studies of e-cigarettes have mainly focused on dehydration and oxidation products of PG and GL. In this study, the other degradation products that can be generated during the vaping process are discussed. In addition, the gas/particle partitioning of chemicals in vaping aerosols is determined. This work finds that the formation of benzene in electronic cigarettes depends on the wattage, types of coils, and devices. To simulate commerical e-cigarette liquids, mixtures containing equal parts of PG and GL by volume were made with the following added components: benzoic acid (BA), benzoic acid with nicotine (Nic), benzaldehyde (BZ), band enzaldehyde with nicotine. PG only, GL only, and PG and GL mixtures were also made for comparison. The data presented here demonstrate that more benzene is generated as the wattage of a device increases. The results also seem to support the importance of ventilation in the generation of benzene. More benzene is generated from the mixtures containing benzoic acid when using the EVOD device with a smaller vent. However, benzaldehyde yields more benzene when using the Subtank Nano device with a larger vent. Findings also indicate that more benzene is produced from GL rather than PG. This thesis also addresses the chemical formation pathways of degradation compounds found in the aerosols formed from isotopically labeled e-cigarette liquids. Mixtures of both 13C-labeled and unlabeled PG as well as GL were made. The mixtures were vaped and gas-phase samples were collected to determine which chemicals were in the gas-phase portion of the aerosols. With the use of GC/MS methods, these isotopic labeling experiments provided evidence that the majority of the benzene, acetaldehyde, 2,3-butanedione, toluene, xylene, acrolein, and furan found in e-cigarette aerosols originates from GL in the PG plus GL mixtures. It was also shown that the majority of propanal is derived from PG: while hydroxyacetone can be formed from both PG and GL. Possible mechanisms for the formation of acetaldehyde, benzene, 2,3-butanedione, toluene, and xylene formation are proposed. Last, this study investigated the gas/particle partitioning of nicotine and flavor-related chemicals in e-cigarette fluids. The gas/particle partitioning behavior of chemicals in e-cigarettes fluids is highly dependent on the chemical volatility. A total of 37 compounds were examined. The target compounds were divided into 3 groups based on their vapor pressures: high, medium, and low. Headspace gas samples were collected and analyzed to determine the concentration of a compound in equilibrium with the liquid phase. The gas and liquid concentrations were used to calculate the gas/particle partitioning constant (Kp) for each compound. In an e-cigarette aerosol, volatile compounds have smaller Kp values and tend to be found in greater proportion in the gas-phase, whereas the less volatile compounds are likely to stay in the particle phase. General agreement with theory was found for compounds with known activity coefficients in PG and GL, indicating that theory can be used to predict Kp values for other compounds.

Linear alkylbenzenesulfonate (LAS) is the most widely used anionic surfactant in commercial detergent formulations. The environmental fate of LAS is of interest because of its disposal to wastewater treatment facilities and subsequent occurrence as a micropollutant in surface waters and groundwater. While LAS fate in wastewater treatment systems and surface waters is well-documented, few studies describe LAS fate in groundwater. This work investigates the transport and biodegradation of LAS in sewage-contaminated groundwater using natural-gradient pulsed and continuous field tracer tests and laboratory column experiments. An "in-vial" disk elution technique that couples solid phase extraction disk elution of LAS as tetrabutylammonium ion pairs with injection-port derivatization was developed for the determination of LAS in groundwater. Pulsed tracer tests then were conducted in an aerobic (~9 mg/L dissolved oxygen) uncontaminated zone, and a moderately aerobic (~1 mg/L dissolved oxygen), sewage-contaminated zone. A continuous injection test also was conducted in the sewage-contaminated zone. Chromatographic separation of the surfactant mixture was observed and attributed to the greater retardation of the longer alkyl chain homologs during transport. In the sewage-contaminated groundwater, biodegradation preferentially removed the longer alkyl chain homologs and external isomers resulting in LAS mixtures that were enriched in the more mobile and biologically-resistant components. LAS mass removal coincided with a decrease in dissolved oxygen concentrations, the appearance of LAS metabolites, and an increase in the number of free-living bacteria. The composition of the LAS mixture changed in the continuous field and column experiments and biodegradation rates increased as dissolved oxygen concentration increased. Mass removal rates were generally 2-3 times greater in the column experiments than in the field for similar dissolved oxygen concentrations. Rate constants for the continuous and pulsed tests conducted in the field were comparable indicating that increased exposure time of the aquifer sediments to the LAS did not increase biodegradation rates. / Graduation date: 1998

Dynamic models of a reactive distillation column have been developed and implemented in this work. A model describing the steady state behavior of the system has been built in a first step. The results from this steady state model have been compared to data provided from an industrial collaborator and the reconciled model formed the basis for the development of a dynamic model. Four controlled and four manipulated variables have been determined in a subsequent step and step tests for the manipulated variables were simulated. The data generated by the step responses was used for fitting transfer functions between the manipulated and the controlled variables. RGA analysis was performed to find the optimal pairing for controller design. Feedback controllers of PID type were designed between the paired variables found from RGA and the controllers were implemented on the column model. Both servo and regulatory problems have been considered and tested.

NMR methods have been designed and employed in studying ofcomplex liquids and solids formed by surfactants. PGSE NMRexperiments are easily biased by convection; this artifact canbe avoided by changing the sample holder and by usingconvection-compensated pulse sequences. The temperaturedistribution within samples was controlled using thetemperature dependent order parameter for CBr2H2dissolved in a thermotropic nematic solvent.Electronic ringing that often spoils accurate NMR experimentsfor broad lines was removed by the using composite pulses andquadrupole echo sequences with appropriate phase cycles. Field-dependent81Br and35Cl NMR relaxation studies in micellar solutions ofC16TAX surfactants showed that the structure ordynamics of the hydration shell is more influenced by thesurfactant cation for bromide than for chloride, in agreementwith their position in the Hoffmeister series. The presence ofa small but significant frequency-dependent relaxation showedthat the lateral self diffusion of the anions may be reduced ascompared to its bulk value in diluted solutions but only with afactor of 1.0 - 2.5. The ions are clearly not "bound" to thesurface. A field-dependent2H NMR relaxation study on the CTABr-α-d2and benzene-d6showed an initial one-dimensional micellargrowth followed by the appearance of microemulsion droplets onaddition of benzene. The local mobility of the benzene wasreduced when solubilized in small amounts, consistent with aninitial average location of benzene at the micellar interface.The surfactant diffusion coefficients fromconvection-compensated PGSE NMR experiments in the C12E8-D2O system showed monotonous growth of the micellesupon increasing temperature. Emulsion droplets in the C12E5-decane-D2O system where shown to coarsen according to theOstwald ripening theory after being brought out of equilibriumby a temperature drop. X-ray scattering and2H NMR line-shape and relaxation experimentssuggested that complex solids formed by a partly-sulfatedpolysaccharide and CnTAB exhibit regular ordering at both microscopicand mesoscopic length scales. <b>Keywords</b>: CTAB, CTAC, C12E8, C12E5, decane, benzene, CBr2H2, polysaccharide, micelle, microemulsion, emulsion,Ostwald ripening, NMR,81Br,35Cl,2H, field- dependent spin relaxation, PGSE, selfdiffusion, convection, ringing, thermometer, generalized Blochequations, EXORCYCLE, quadrupole echo, SAXS, WAXS, cryo-TEM.

Abstract The search for nanoscale active electronic devices has been an important objective in nanoscience and nanotechnology. In this study, the electronic and transport properties of the benzene-1,4-dithiol-molecule (BDT) and Au-atom-S-benzene-ring-O-(SBO)-Au-atom junctions and the Au-AlN(0001)-Au polar semiconductor junction have been calculated using the first-principles calculation method and a new integrated piecewise thermal equilibrium approach for the current. The current-voltage (I-V) and conductance-voltage (C-V) characteristic curves obtained for the Au-BDT-Au molecular junction agreed reasonably well with experimental ones. The study of Au-BDT-Au identifies that treating Au 5d electrons as core electrons and letting the S end of BDT be bonded to the Au surface directly overestimated the current. Calculated I-V characteristic curve revealed that the asymmetric Au-SBO-Au molecular junction has a pulse-like I-V characteristic curve with dual differential conductance, which resembled well the one observed experimentally. The analysis of the electronic structures showed that this dual differential conductance transport property was due to a subtle charge transfer at the electrode-molecule contacts. The calculated J-V characteristic curve of the Au-Al(0001)-Au junction shows coexistence of ohmic, switching effect and negative differential conductance. The electronic structure calculations show the existence of an intrinsic band tilt due to the polar nature of the AlN(0001) film, which gives rise to an asymmetric transport property of the junction and the presence of hole states at the N-surface side and interface states at the Al-surface side of the AlN film. The bias induced changes of the hole states, interface states and the states of the Al and N ions in central layers in the vicinity of the local chemical potential give rise to the interesting transport property of the Au-AlN(0001)-Au junction.