Estudo do desempenho de eletrodos de dióxido de chumbo depositados sobre diferentes substratos para o tratamento eletroquímico de soluções contendo corantes têxteis

• Ano de defesa: 2013
• Autor(a) principal: Irikura, Kallyni
• Orientador(a): Bocchi, Nerilso
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de São Carlos
• Programa de Pós-Graduação: Programa de Pós-Graduação em Química - PPGQ
• País: BR
• Palavras-chave em Português: Eletroquímica; Eletrooxidação de corantes; Dióxido de chumbo; Planejamento fatorial
• Área do conhecimento CNPq: CIENCIAS EXATAS E DA TERRA::QUIMICA
• Link de acesso: https://repositorio.ufscar.br/handle/20.500.14289/6283

PbO2 films were grown galvanostatically on different substrates (titanium Ti, platinized titanium Ti- Pt and carbon fiber CF) and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and linear potential sweep in H2SO4. SEM micrographs revealed the growth of PbO2 films well distributed, uniform and compact. The diffractograms presented the formation of PbO2 films of a single phase (&#946; -PbO2). From the potential sweep (30 mV s 1), the overpotential values for the OER of Ti/&#946;- PbO2, Ti-Pt/&#946; -PbO2 and CF/&#946;-PbO2 electrodes were obtained, respectively: 2.15 V; 2.20 V and 2.33 V vs. SCE. The electrochemical performance of these electrodes was investigated in electrooxidations of solutions containing the dyes acid green 28 (AG 28) and yellow direct 12 (YD 12), employing a reactor filter-press type and the experimental design methodology by varying the following experimental parameters: pH, current density (j), temperature (&#920;) and NaCl concentration ([NaCl]). For AG 28 dye, the Ti-Pt/&#946;-PbO2 and Ti/&#946;-PbO2 electrodes presented the lowest values of charge for color removal (Q90 ~0.5 A h L 1) and the highest values of % COD removal (87 99 %) in the following experimental conditions: pH = 5, j = 50 mA cm-2, &#920;&#61472;= 25 ºC and [NaCl] = 1.5 g L 1, while the CF/&#946;-PbO2 electrode presented the lowest Q90 value (0.20 A h L 1) and the highest % COD value (86%) in the following experimental conditions: pH = 9, j = 30 mA cm-2, &#920;&#61472;= 45 ºC and [NaCl] = 1.5 g L 1. The &#946;-PbO2 films grown on Ti and Ti-Pt exhibited chemical stability ([Pb2+] < 0.5 mg L 1) in solutions of pH > 3, while those grown on FC showed chemical stability only at pH 9. For the YD 12, the Ti-Pt/&#946;-PbO2 and Ti/&#946;-PbO2 electrodes presented the lowest Q90 values (0.57 0.68 A h L 1) and the highest % COD values (96 100 %) in the following experimental conditions: pH = 5, j = 30 mA cm 2, &#920;&#61472;= 45 ºC and [NaCl] = 1.5 g L 1. Comparing the performance of Ti-Pt/&#946;-PbO2 and Ti/&#946;-PbO2 electrodes with that of commercial ones of Nb/BDD and DSA, the first presented, for the AG 28 dye, better performance than the DSA and comparable to the Nb/BDD. In the case of the AD 12 dye, the Ti-Pt/&#946;-PbO2 and Ti/&#946;-PbO2 electrodes showed performance comparable to the DSA and lower than the Nb/BDD.