Degradação eletroquímica do corante amarelo reativo 145 utilizando ânodo DSA comercial

Abstract

The textile industry has a high pollutant potential, mainly due to the generation of large volumes of effluents, containing dyes not fixed during the fiber dyeing process. In textile processing, a wide range of dyes is released, among them the azo dyes, which are characterized by the azo function (-N = N-) linked to aromatic groups and can be toxic, carcinogenic and / or mutagenic. The problem becomes even more critical, due to the low efficiency of the processes usually used in the treatment of these effluents. Studies show that polluting organic compounds can be efficiently electrooxidized in aqueous solutions, making electrochemistry a promising technology to remedy environmental problems. Within this context, the present study consisted of evaluating the efficiency of the electrochemical technique in the degradation of Reactive Yellow 145 (AR145), with a commercial DSA® electrode, in different electrolyte compositions, H2SO4 0.1 mol L- 1, Na2SO4 0, 1 mol L-1, NaCl 0.1 mol L-1, Na2SO4 0.1 mol L-1 + NaCl 6.25 mmol L-1 and Na2SO4 0.01 mol L-1 + NaCl 0.05 mol L-1 , the last composition being the one with the best efficiency. The influence of the current density variation applied to the anode (25, 50 and 100 mA cm-2) was also studied, after 180 min of electrolysis. As the current density increases, it is expected that there will be an increase in the amount of oxidized species formed and, consequently, a greater amount of degraded matter, but the increase in the amount of formed species may favor, in addition to the degradation reaction, parallel reactions, additionally the oxidation reaction of the pollutant occurs simultaneously, the reaction of release of oxygen (RDO) and chlorine (RDCl), and the increase in the current can increase the efficiency of these reactions and not the oxidation of the pollutant. Therefore, the best experimental condition determined was the use of Na2SO4 0.1 mol L-1 + NaCl 0.05 mol L-1 as a support electrolyte and the current density of 25 mA cm-2, because, in addition to demonstrating a decrease in the concentration of AR145 and COD close to the other current densities used, it was with this density that we obtained the best efficiency results.