Electrochemistry and green chemical processes: electrochemical ozone production

Abstract

Recebido em 25/11/02; aceito em 1/4/03After an introductory discussion emphasising the importance of electrochemistry for the so-called Green Chemical Processes, the article presents a short discussion of the classical ozone generation technologies. Next a revision of the electrochemical ozone production technology focusing on such aspects as: fundamentals, latest advances, advantages and limitations of this technology is presented. Recent results about fundamentals of electrochemical ozone production obtained in our laboratory, using different electrode materials (e.g. boron doped diamond electrodes, lead dioxide and DSA  -based electrodes) also are presented. Different chemical processes of interest to the solution of environmental problems involving ozone are discussed.

Trends and strategies of ozone application in environmental problems

“…Physical separation of suspended solids, oils and greases, and biological treatments, have been shown to be very economical and reliable systems in the cases of municipal wastewater, food and farm processing water 7 . However, there are cases in which the effectiveness of these treatments drops away (e.g., soluble substances requiring physical separation, recalcitrant compounds, toxic substances for biological treatment), and, therefore, different chemical processes are used as a coadjutant in order to perform a more efficient effluent treatment [4][5][6] . Classical wastewater technologies based upon phase transfer merely concentrate the pollutants, which then have to be eliminated in a further treatment step.…”

“…Several applications for ozonation and related AOP in wastewater treatment are available 5,13,15,16,57 . Examples of the use of ozone to degrade organic contaminants in wastewaters are pulp and paper production, shale oil processing, production of pesticides, dye manufacture, textile dying and pharmaceutical production.…”

“…The increasing world population with growing industrial demands has led to a situation where protection of the environment has become a major issue and a crucial factor for several industrial processes, which will have to meet the requirements of the sustainable development of modern society [1][2][3][4][5] . In order to combine industrial activities with preservation of the environment (sustainable development), there is a tendency in most countries to adopt rigid environmental legislation where the well-known Green Technology plays a key role.…”

Aplicação da tecnologia de eletrofloculação na recuperação do corante índigo blue a partir de efluentes industriais

“…O eletrodo de trabalho empregado, β-PbO 2 , apresenta boa estabilidade e eficiência na geração de oxigênio gasoso sob estas condições 31,[34][35][36] . Durante as eletrólises foi observado que a solução verde-escura inicial foi se alterando para verde-clara até se estabilizar na coloração azul, depois de apenas 45 min de eletrólise.…”

Investigação da tecnologia eletroquímica para a produção de ozônio: aspectos fundamentais e aplicados

“…Apesar do grande número de investigações do processo eletroquímico de produção de ozônio, uma revisão da literatura revela que a grande maioria dos estudos da RFO concentram-se sobre o PbO 2 [107], sendo portanto escasso estudos sistemáticos envolvendo a RFO sobre outros tipos de óxidos [17]. Portanto, a investigação de materiais eletródicos alternativos, constituídos de outros óxidos, objetivando a geração de ozônio, torna-se uma tarefa de grande interesse não só do ponto de vista fundamental, como também do ponto de vista tecnológico.…”