Submitted by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-02-19T13:34:46Z No. of bitstreams: 5 tel.pdf: 9429138 bytes, checksum: 55c9c9a1eb3f75db9e65b286cec95dda (MD5) license_url: 52 bytes, checksum: 3d480ae6c91e310daba2020f8787d6f9 (MD5) license_text: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) license.txt: 2110 bytes, checksum: b4c884761e4c6c296ab2179d378436d4 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-02-20T11:03:29Z (GMT) No. of bitstreams: 5 tel.pdf: 9429138 bytes, checksum: 55c9c9a1eb3f75db9e65b286cec95dda (MD5) license_url: 52 bytes, checksum: 3d480ae6c91e310daba2020f8787d6f9 (MD5) license_text: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) license.txt: 2110 bytes, checksum: b4c884761e4c6c296ab2179d378436d4 (MD5) / Made available in DSpace on 2015-02-20T11:03:29Z (GMT). No. of bitstreams: 5 tel.pdf: 9429138 bytes, checksum: 55c9c9a1eb3f75db9e65b286cec95dda (MD5) license_url: 52 bytes, checksum: 3d480ae6c91e310daba2020f8787d6f9 (MD5) license_text: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) license.txt: 2110 bytes, checksum: b4c884761e4c6c296ab2179d378436d4 (MD5) Previous issue date: 2013-02-20 / Funda??o de Amparo ? Pesquisa do estado de Minas Gerais (FAPEMIG) / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) / A hidrazina ? uma subst?ncia utilizada como inibidora de corros?o, antioxidante, catalisador, emulsificante, agente redutor, combust?vel para propuls?o de foguete, inseticidas, e na prepara??o de diversos derivados farmac?uticos. Por?m, a hidrazina ? um material t?xico, sendo, portanto, necess?rio um m?todo sens?vel para a sua determina??o. Neste trabalho um sensor foi desenvolvido para determina??o de hidrazina mediante modifica??o de um eletrodo de carbono v?treo com ftalocianina de cobalto adsorvido em nanotubos de carbono de paredes m?ltiplas. A caracteriza??o eletroqu?mica e de superf?cie foi feita por voltametria c?clica, microscopia eletr?nica de varredura, FT-IR e Espectroscopia de Energia dispersiva de Raios-X. Os estudos de superf?cie deixaram evidente que os NTCPM e a CoPc formam um material comp?sito. Os estudos eletroqu?micos mostraram a ocorr?ncia de processos redox de superf?cie e ainda h? ind?cios de uma limita??o da transfer?ncia de carga. O n?mero de el?trons para a rea??o de oxida??o de hidrazina bem como a constante de velocidade heterog?nea foram estimados a partir dos coeficientes linear e angular das curvas de Koutecky-Levich sendo, respectivamente, 4,1 e 1,51 x 103 M-1s-1. Os par?metros operacionais de tr?s t?cnicas eletroanal?ticas (Amperometria, VPD e VOQ) foram otimizados em rela??o ? determina??o de hidrazina com o uso do ECV/NTCPM/CoPc, sendo que a VOQ apresentou maior sensibilidade, tendo sido, portanto, escolhida para a determina??o da hidrazina em ?gua de caldeira. Uma curva anal?tica final para a determina??o de hidrazina em amostra da ?gua de caldeira foi feita utilizando-se eletrodos impressos, sob condi??es experimentais otimizadas, apresentando resposta linear no intervalo de concentra??o de 99 a 7630 ?mol L-1, com R igual a 0,999. Foram obtidos valores de LD e LQ iguais a 50 e a 99 ?mol L-1, respectivamente. O sensor permitiu uma boa recupera??o para a hidrazina nas amostras de ?guas de caldeiras analisadas, com valores de recupera??o compreendidos entre 98,41 e 103,62%, atestando a exatid?o do m?todo proposto. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Qu?mica, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2011. / ABSTRACT Hydrazine is used as a corrosion inhibitor, antioxidant, catalyst, emulsifier, reducing agents, fuel for rocket propulsion, insecticides, and pharmaceutical preparation of various derivatives. However, the hydrazine is a toxic material and therefore requires a sensitive method for its determination. In this paper a sensor was developed for determination of hydrazine by modifying a glassy carbon electrode with cobalt phthalocyanine adsorbed on mutiwalled carbon nanotubes. The surface and electrochemical characterization was carried out by cyclic voltametry, scanning electron microscopy and energy dispersive spectroscopy X-ray. Surface studies shows that NTCPM and CoPc are a composite material. Electrochemical studies have shown the occurrence of redox processes of surface and also an indication of a limited transfer of load transfer. The number of electrons for the reaction of oxidation of hydrazine and the observed average rate constant of the process were estimated from the coefficients of linear and angular curves Koutecky-Levich being, respectively, 4,1 and 1,51 x 103 M-1s-1. The operational parameters of three electroanalytical techniques (amperometry, VOQ and VPD) were optimized for the determination of hydrazine with the use of ECV / NTCPM / CoPc, although the VOQ showed greater sensitivity and was therefore chosen for the determination of hydrazine in boiler water. A final analytical curve for the determination of hydrazine in boiler water sample was made using electrodes printed under optimized experimental conditions, with linear response over the concentration range of 99 mmol L-1 to 7630 ?mol L-1, with R equal to 0.999. We obtained values ??of LOD and LOQ equal to 50 and 99 ?mol L-1, respectively. The sensor allowed a good recovery for hydrazine in boiler water samples analyzed, with recovery values ??ranging between 98.41 and 103.62%, attesting to the accuracy of the proposed method.