Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2018-03-08T18:31:35Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) jose_geraldo_mendes_castro_junior.pdf: 20723597 bytes, checksum: f867ab4f1cb9235c24c8c6d16d42c22c (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2018-03-09T18:46:17Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) jose_geraldo_mendes_castro_junior.pdf: 20723597 bytes, checksum: f867ab4f1cb9235c24c8c6d16d42c22c (MD5) / Made available in DSpace on 2018-03-09T18:46:17Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) jose_geraldo_mendes_castro_junior.pdf: 20723597 bytes, checksum: f867ab4f1cb9235c24c8c6d16d42c22c (MD5) Previous issue date: 2017 / Eletrodos de di?xido de chumbo (PbO2) suportados sobre tecido de carbono e tela de a?o inoxid?vel foram utilizados na degrada??o eletroqu?mica dos f?rmacos paracetamol (PCT) e dipirona (DPN), utilizando-se uma c?lula eletroqu?mica do tipo eletr?lito polim?rico s?lido (EPS) munida de eletrodos perme?veis a fluidos (EPFs). Todos os estudos foram conduzidos na condi??o de batelada empregando-se a ?gua livre de eletr?litos. Os estudos eletroqu?micos de degrada??o dos f?rmacos foram conduzidos em fun??o da densidade de corrente aparente (jap) (ex., 5, 10, 20, 100, 150 e 200 mA cm-2) e da concentra??o inicial (ex., 10, 30 e 50 mg L 1). As amostras tratadas foram analisadas pelas t?cnicas de espectrofotometria na regi?o do UVVis, cromatografia l?quida de alta efici?ncia (CLAE) e demanda qu?mica de oxig?nio (DQO). Verificou-se para os diferentes casos envolvendo as baixas densidades de corrente que a remo??o das bandas de absor??o no UV-Vis, a remo??o da concentra??o dos f?rmacos (CLAE) e a redu??o da DQO (grau de mineraliza??o) n?o foram significativos. Contrariamente, no caso das elevadas densidades de corrente evidenciou-se uma significante melhora na degrada??o dos f?rmacos em decorr?ncia da atua??o do oz?nio gerado eletroquimicamente. Os melhores resultados foram obtidos para baixas concentra??es dos f?rmacos. Redu??es superiores a 95 % de DQO para o PCT e superiores a 75 % para a DPN foram obtidas. Eletrodos de PbO2 dopados com n?quel (ex., Ni-PbO2) suportados sobre tecido de carbono e tela de a?o inoxid?vel foram confeccionados e caracterizados. A an?lise de microscopia eletr?nica de varredura (MEV) revelou o aparecimento de defeitos superficiais, com a varia??o da concentra??o nominal do Ni no banho eletrol?tico utilizado no preparo do eletrodo por eletrodeposi??o. An?lises de difratometria de raios-X (DRX) corroboraram os resultados de MEV revelando, em alguns casos, picos mais alargados e de menor intensidade (ex., redu??o no tamanho m?dio dos cristalitos) com a varia??o da concentra??o nominal do Ni, indicando assim uma interfer?ncia no processo de eletrodeposi??o do PbO2. Curvas de polariza??o em condi??es quaseestacion?rias foram obtidas para o processo eletr?dico da rea??o de desprendimento de oxig?nio (RDO) sendo verificado que n?o houve influ?ncia significativa do dopante sobre esta rea??o, a qual ocorre em paralelo ao processo de degrada??o oxidativa dos f?rmacos. Verificou-se que a produ??o de oz?nio foi ligeiramente favorecida em algumas concentra??es do dopante e em altas densidades de corrente. No entanto, n?o foi verificada influ?ncia significativa sobre o grau de mineraliza??o dos f?rmacos PCT e DPN mediante uso de eletrodos dopados com Ni. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Qu?mica, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2017. / Lead dioxide (PbO2) electrodes supported on carbon cloth and stainless-steel mesh substrates were used in the electrochemical degradation of the drugs paracetamol (PCT) and dipyrone (DPN), using a solid polymer electrolyte electrochemical cell (SPE) having fluid-permeable electrodes (FPEs). All studies were conducted in batch condition using the electrolyte-free water. The electrochemical degradation of the drugs was accomplished as a function of the apparent current density (ex., 5, 10, 20, 100, 150 and 200 mA cm-2) and the initial concentration (ex., 10, 30 and 50 mg L-1). The treated samples were analyzed using the UV-Vis spectrophotometry technique, the high-performance liquid chromatography (HPLC), as well as the chemical oxygen demand (COD). For the different cases involving the application of low current density values, it was not verified significant changes accounting for the removal of the UV-Vis absorption band, the drug concentration (HPLC), and the COD decrease (ex., the degree of mineralization). In contrast, in the case of high current densities, a significant improvement in the degradation of the drugs was evidenced as a result of the influence of the electrochemically generated ozone. The best findings were obtained for low drug concentrations. Reductions of above 95% COD for PCT and above 75% for DPN were obtained. Nickel-doped PbO2 electrodes (ex., Ni-PbO2) supported on carbon cloth and stainlesssteel mesh were fabricated and characterized. Scanning electron microscopy (SEM) revealed the appearance of surface defects with a reduction in crystal size with the different Ni concentration in the electrolytic bath used to prepare the electrode by electrodeposition. X-ray diffraction (XRD) analyzes corroborated with the SEM results revealing the formation of broader peaks with lower intensity, in some cases, (ex., reduction in the average crystallite size) with the variation of the nominal dopant concentration in the electrolytic bath, thus indicating an interference in the electrodeposition process for PbO2. Quasi-stationary polarization curves were obtained for the electrode process of the oxygen evolution reaction (OER) and it was verified that there was no significant influence of the dopant on this reaction, which occurs in parallel to the process comprising the oxidative degradation of the drugs. It was found that the ozone generation was slightly favored in some concentrations of the dopant and in higher current densities. However, no significant influence was verified on the degree of mineralization of PCT and DPN by the use of Ni-PbO2 electrodes.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-10-25T22:39:49Z No. of bitstreams: 1 GilbertoDeLima_DISSERT.pdf: 6145295 bytes, checksum: bc53e57020e12cd1c59df71eaa9312a9 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-12-16T20:13:09Z (GMT) No. of bitstreams: 1 GilbertoDeLima_DISSERT.pdf: 6145295 bytes, checksum: bc53e57020e12cd1c59df71eaa9312a9 (MD5) / Made available in DSpace on 2016-12-16T20:13:09Z (GMT). No. of bitstreams: 1 GilbertoDeLima_DISSERT.pdf: 6145295 bytes, checksum: bc53e57020e12cd1c59df71eaa9312a9 (MD5) Previous issue date: 2016-02-05 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Filmes polim?ricos autossustent?veis baseados em um novo eletr?lito polim?rico s?lido (EPS), tendo como matriz hospedeira o poli(?xido de etileno) (POE) e como agente dopante o tungstato de s?dio (Na2WO4), foram obtidos para diferentes composi??es do sal (m = 0,20; 0,26; 0,30; 0,40; 0,50 e 1,31 mg). Os filmes foram caracterizados por DRX, FTIR, MEV/EDS, TG/DTG, DSC e EI. Os difratogramas de raios X confirmaram a natureza semicristalina do pol?mero e sugeriram que a adi??o do sal provoca uma redu??o na cristalinidade dos filmes. Os dados de FTIR permitiram a an?lise da intera??o entre os ?ons do sal e as cadeias polim?ricas. As micrografias obtidas por MEV demonstraram morfologia esferul?tica intercaladas por liga??es interlamelares para todas as composi??es estudadas. O estudo de TG/DTG mostrou que a decomposi??o t?rmica do eletr?lito ocorre em uma ?nica etapa com a adi??o do sal aumentando a estabilidade t?rmica dos filmes. Os dados de TG/DTG permitiram, ainda, o estudo cin?tico da decomposi??o t?rmica do eletr?lito por meio dos m?todos de Briodo (BR), Coats-Redfern (CR) e Horowitz-Metzger (HM) sugerindo uma cin?tica de 1? ordem para a rea??o de decomposi??o t?rmica dos filmes, assim como, a determina??o dos par?metros termodin?micos de ativa??o: E*, ?H*, ?S* e ?G*. O grau de cristalinidade foi determinado atrav?s dos dados de DSC e mostrou uma redu??o ap?s a adi??o do sal ao pol?mero. O eletr?lito POE/Na2WO4 exibiu um m?ximo de condutividade i?nica de 3,24x10-4 S.cm-1, a temperatura ambiente, para o filme com 1,31 mg do sal. Atrav?s dos dados de imped?ncia foi poss?vel o estudo de relaxa??o das cadeias do POE, assim como, a difus?o do sal entre estas cadeias. Os diagramas de imped?ncia, nos formatos Bode e Nyquist, permitiram o ajuste dos dados experimentais ? circuitos el?tricos equivalentes o que facilitou a associa??o dos componentes dos circuitos aos fen?menos f?sicos e qu?micos observados para os filmes e revelaram que, ap?s a adi??o do sal ao pol?mero, os filmes t?m suas propriedades el?tricas melhoradas. / Self-sustainable polymeric films based on new solid polymer electrolyte, having the poly(ethylene oxide) (PEO) as host matrix and sodium tungstate as doping agent (Na2WO4), were obtained from different salt compositions (m = 0.20; 0.26; 0.30; 0.40; 0.50 and 1.31 mg). The films were characterized through XRD, FTIR, SEM/EDS, TG/DTG, DSC and IS. X-ray diffraction showed the semi crystalline nature of the polymer and confirmed that the addition of salt induces reduction in the crystalinity of the films. FTIR data allowed the identification of the interaction between salt ions and polymer chains and confirmed that these interactions are of a physical nature. The micrographs obtained through SEM showed spherulitic morphology interleaved by interlayered bonds for all of the compositions studied. The TG/DTG study revealed that the thermal decomposition of the electrolyte almost happens at a single stage with the addition of salt, increasing the thermal stability of the films. TG/DTG data also allowed the kinetic study of the thermal decomposition of the electrolyte through Broido (BR), Coats-Redfern (CR) and Horowitz-Metzger (HM) methods, suggesting a first-order kinetic for the reaction of the thermal decomposition of the films, as well as the setting of pre-exponential factor, A, and the thermodynamic activation parameters: E*, ?H*, ?S* and ?G*. The crystallinity degree was determined through DSC data and showed a reduction after the addition of salt to the polymer. The polymer has its conductivity increased after addition of the salt with the PEO-Na2WO4 electrolyte exhibiting maximum of ionic conductivity of 3.24x10-4 S cm-1, to room temperature, for the film with 1.31 mg of salt (F6 film). The impedance data allowed the study on relaxation on PEO chains, even as the diffusion of salt between these chains. The impedance diagrams, on Bode and Nyquist formats, enabled the adjustment of the experimental data to equivalent electric circuits, which facilitated the association of the circuit components to the physical and chemical phenomena observed for the films and revealed that, after the addition of salt to the polymer, the films have their electrical properties enhanced.