Tratamento eletroquímico de azo corantes em solução aquosa usando anodos de Ti/Ru0,3 Ti0,7 O2, Ti/Ru0.3 Sn0,7 O2 e Ti/Ru0,3 Ti0,4 Sn0,3 O2

Abstract

This study presents the investigation about the efficiency of electrooxidation process in the degradation in aqueous solution and at room temperature (25°C) of Acid Red 27 and Acid Red 66 azo dyes in different concentrations (5, 10, 15 and 25 mg/L) under different electrolysis potentials (1.0, 1.25, 1.5 and 2.5 V) using as active electrochemical phase oxides type TiO2, RuO2 and SnO2 supported on metallic titanium. For the electrochemical treatment were used dimensionally stable anodes of Ti/Ru0,3Ti0,7O2, Ti/Ru0,3Sn 0,7O2 and Ti/Ru0,3Ti0,4Sn0,3O2 prepared by thermal decomposition and characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy ( EDX). The SEMimages showed a cracked-mud like surface for the oxides deposited on the titanium substrate, indicating a high surface area for electrocatalysis. The results of the EDX indicated experimental compositions close to the initial nominal compositions in the different electrodes. Voltammetric studies also showed elevated mechanical and chemical stabilities of the deposited oxides. From the point of view of electrochemical treatment, the main efficiencies of the electrocatalytic degradation to an initial concentration of 25 mg/L were observed in neutral medium (pH = 7.0) under the potential of 2.5 V by using the electrode Ti/Ru0,3Ti0,4, Sn0,3O2, which were 88.1% for the Acid Red 27 and 86.4% for the Acid Red 66. Regarding the kinetic modeling, it became evident a typical first-order behavior in all systems. Physico-chemical characterization and toxicity with Aspergillus niger showed moderated reductions in organic matter (38.1 to 59.6 %) and high fungal growth after treatment, confirming the promising character of t he electrochemical treatment studied in the decontamination of aqueous systems containing recalcitrant azo dyes, extremely harmful to the environment