Degradação de alisarina em solução aquosa, sob plasma obtido por eletrólise de alta tensão e baixa corrente

• Ano de defesa: 2007
• Autor(a) principal: Griep, Viviane Nunes
• Orientador(a): Reis, Efraim Lázaro
• Banca de defesa: Braathen, Per Christian
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Agroquímica
• Departamento: Agroquímica analítica; Agroquímica inorgânica e Físico-química; Agroquímica orgânica
• País: BR
• Palavras-chave em Português: Eletrólise; Plasma; Alta voltagem; Degradação; Alisarina; Corante
• Palavras-chave em Inglês: Plasma; Electrolysis; High voltage; Degradation; Alisarina; Dye
• Área do conhecimento CNPq: CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ANALITICA
• Link de acesso: http://locus.ufv.br/handle/123456789/2157

In this present work, the construction of a system for degradation of organic substance by high voltage and low current is proposal, using alizarin as model compound. This technique is part of an Advanced Oxidation Process (AOP) that is based on the generation of highly oxidative species, mainly the hydroxyl radical (OH). Due to the concern with environmental impact ant the need for the use of dyes for the textile industries, during the last years several studies has been undertaken to develop new technologies for energetic treatments that allows for the degradation of compounds present in industrial waste. The used system is constituted of a continuous current high voltage source, a thermostatic cell and two electrodes where the plasma is established. The cathode is formed by a spectroscopic graphite electrode and the anode is formed by a platinum electrode sealed in a glass tube, with a microelectrode in contact to the solution. In all samples, a potential difference of 600 volts was applied for a total reaction time of 60 minutes for the degradation of the alizarin at a concentration of 1,05 x 10-4 mol L-1. The monitoring of the degradation of the alizarin was done by spectroscopic scanning in the region of 300 to 600 nm, in aliquots removed from the reaction solution each five minutes. The concentration of iron(II) and the pH variation of the alizarin solutions were investigated to evaluate their interference on the rate of the alizarin degradation. Also, the characteristics of the voltage and current in the sodium sulphate solution were investigated. The proposed degradation system for the Alizarin under plasma obtained by high voltage electrolysis caused the degradation of 70% of the compound. A pH interference in the rate of degradation of the compound was observed, and adjusting the sample pH to 8, a result of 78% of degradation of the compound was obtained. In accordance with this present work, the addition of iron(II) has a great effect as reaction catalyser, being able to observe a rate of degradation of 90%, in a Fe2+ defined concentration. The electrolysis by electric discharge is a technique with great potential for the degradation of organic compounds and the reaction can be catalyzed by the addition of iron(II).