Análise dos processos de eletro-oxidação simples e foto-assistido usando ânodo de mistura de óxidos metálicos comercial em meio alcoólico e atrazina como composto modelo

Abstract

Water contamination has been extensively studied due to its scarcity, aggravated by poor management of water resources. One of the pollutants that has received the most attention is atrazine, a herbicide widely used in agriculture. Therefore, studies of new technologies for the treatment of effluents as electrochemical processes, have become important alternative methods to the conventional ones. However, considering the low concentrations (high dilution) of these pollutants in water, an inherent problem is the low effectiveness of these alternative methods and, consequently, the high energy consumption. Therefore, a new adsorption pre-concentration methodology that can be integrated into the degradation process is being implemented to avoid the limitations of direct electrochemical treatment. Atrazine is a poorly soluble in water, which, when nonaqueous solventes are used, facilitates desorption in a small volume for electrochemical treatment. In this work, atrazine was degraded in methanol media in the presence of different proportions of water (0%, 5% and 10%) using a commercial mixed metal oxide anode and sodium chloride as supporting electrolyte. The results obtained showed atrazines removals up to 99.8% after 1h of electrolysis. The variation of the current density during electrolysis demonstrated that atrazine is removed more quickly at high currents. The initial pH of the solution influences the process due to the formation of different species of active chlorine. The detection of the radicals produced helped to better understand the process and the species generated during the electro-oxidation in the methanol medium. On the other hand, the coupling of photo-assistance with electrooxidation showed a synergy between these processes, improving considerably the efficiency of atrazine degradation and demonstrating that the implementation of methanol as a medium is a promising method to degrade pollutants in effluents.