Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin, 1967. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1968. / Includes reprint of Exchange equilibrium through anion exchange membranes [by] W.J. Blaedel and E.L. Christensen, from Analytical chemistry, vol. 39, p. 1262, September 1967. Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1982. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph.D.) -- McMaster University, 2001. / Includes bibliographical references. Also available via World Wide Web.

Thesis (Ph. D.)--Lehigh University, 2000. / Includes vita. Includes bibliographical references (leaves 205-221).

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas. Programa de Pós-Graduação em Química / Made available in DSpace on 2012-10-22T21:34:39Z (GMT). No. of bitstreams: 1 233951.pdf: 826534 bytes, checksum: d460258e0ca2e640e7efc0c07106541e (MD5) / As bifenilas policloradas (PolyChlorinated Biphenyl, PCBs) foram produzidas em vários países, com diferentes denominações. Este produto foi comercializado no Brasil com o nome de "Ascarel" e muito utilizado até a década de oitenta, quando da sua proibição, principalmente no setor elétrico (em transformadores de alta tensão como liquido isolante). Estima-se que até esta década a produção mundial acumulada foi de aproximadamente 1.200.000 toneladas, deste total, cerca de 60% foi utilizado em transformadores e capacitores. No processo de substituição do ascarel por óleo mineral a base de silicone houve a contaminação do novo material devido à falta de critérios técnicos. Desta forma, muitos dos grandes transformadores, ainda em operação no Brasil, estão contaminados em níveis acima dos permitidos pela legislação vigente. Por este motivo é necessário desenvolver técnicas simples e baratas de detecção e descontaminação do líquido isolante, que possam ser facilmente aplicadas em campo. Sendo assim, o desenvolvimento deste trabalho se baseou num método promissor a partir da reação de desalogenação via ânion radical naftaleno e a análise por potenciometria com eletrodo íon seletivo para cloreto, onde as concentrações iônicas são obtidas diretamente do potencial do eletrodo de membrana seletiva a esse íon específico. Inicialmente foram utilizadas amostras de 1,2,4-triclorobenzeno e por conseguinte, amostras reais de óleo isolante de transformador contaminadas com ascarel entre 0 a 200 mg L-1. A potenciometria de íon seletivo para cloreto foi comparada com a metodologia padrão para detecção de ascarel (PCBs) que é feita por cromatografia gasosa com detector de captura de elétrons. O método mostrou-se eficiente com excelentes resultados com possibilidade de ser usado no campo por técnicos com treinamento especializado. PolyChlorinated Biphenyl, PCBs were produced in several countries, commercialized in Brazil as Ascarel, widely used since eighties in high tension transformers as insulating oil. Due to its toxicity Ascarel was substituted with silicone oil. The substitution process, due to a lack of technical criteria, the new oil was contaminated. Therefore, many transformers in Brazil are contaminated in levels above permitted by Brazilian law. Thus new techniques able to detect Ascarel, with low operational costs, are very attractive. The present work, proposes an analysis, of the contaminated levels of silicon oil using the following techniques; naphthalene anion radical reaction for Ascarel dechlorination; and potentiometry with ion selective electrode for chloride ion determination. Sample of pure trichlorobenzene and transformer insulating oil contaminated with PCB in the range of 0 to 200 mg L-1 were used. The result obtained from potentiometry was compared with standard method for PCBs determination by gas chromatography with electrons capture detector. The data obtained with the proposed methodology agree well with those from the official methodology, (method IEC 61619).

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No description available.

The radical anions and ion-pairs of 1,8-dinitro-naphthalene and 1,4,5,8-tetranitronaphthalene have been perpared and the electron spin resonance spectra have been investigated in detail. The spectra were interpreted completely in terms of a set of two equivalent nitrogen atoms and three sets of two equivalent hydrogen atoms for the 1,8-dinitronaphthalene radical, four equivalent nitrogen atoms and four equivalent hydrogen atoms for the 1,4,5, 8-tetranitronaphthalene radical, respectively. The hyper-fine splitting constants obtained are compared with the values derived from molecular orbital calculations. In the ion-pairs of 1,8-dinitronaphthalene the distinct alkali metal hyperfine splitting have been observed The magnitude of the metal hyperfine splitting shows remarkable temperature dependency, and the temperature dependence is interpreted in terms of the cation exchange mechanism b between two nitro groups of 1,8-dinitronaphthalene. In the anion radical of 1,8-dinitronaphthalene as well as in the corresponding ion-pairs, anormalous line width variation has been observed. This behaviour is interpreted in terms of the cation exchange mechanism and supports the hypothesis proposed for the temperature dependence of alkali metal splitting in the ion-pairs of the compound. In the anion radical of 1,4,5,8-tetranitronaphtha-lene the twisting angle of the nitro group from the plane of aromatic ring is estimated to be (35 ±10)° from the observed splitting constants by employing the spin densities obtained with McLachlan method. The temperature dependency of the nitrogen and hydrogen splittings has been determined. The phenomenon is explained in terms of a hindered rotation of.the nitro group in 1,4,5,8-tetranitronaphthalene. From the asymmetry of the spectra it is predicted that the spin density on the nitrogen nucleus is positive. / Science, Faculty of / Chemistry, Department of / Graduate