Influence of the Electrocatalytic Anode Nature on Dye Destruction

Abstract

AbstractIn order to extract a highly concentrated dye from textile industry wastewater, an electrocatalytic oxidation method based on Ru/Ir/Ti, RuO2/IrO2/TiO2 electrodes and high‐density graphite was used. Optimization of the oxidation process was controlled by varying such parameters as current density, pH, concentration of supporting electrolyte (NaCl), wastewater treatment time. The maximum dye removal from wastewater is achieved at pH 7.1, current density 70 mA cm−2, NaCl concentration 3 g/L, and treatment time 15 minutes. Among the investigated electrodes, the Ru/Ir/Ti anode and titanium‐based oxides of these metals proved to be the most effective. The percentage of color removal for all anodes increases with increasing current density and duration of solution treatment. For a graphite electrode, at a current density of 70 mA cm−2 and a treatment time of 10 minutes, a maximum dye removal of 90 % is achieved. The percentage of color removal for Ru/Ir/Ti and RuO2/IrO2/TiO2 electrodes is higher than for graphite and amounted to 98 % and 92 %, respectively. The results of the electronic structure of the dye made it possible to shed light on the nature of the electronic spectra and the possible mechanism of the electrocatalytic act. Consideration of the dependence of color removal, COD and TOC on such parameters as current density, water treatment time in the reactor showed that the efficiency of the wastewater treatment process increases in the series: graphite<RuO2/IrO2/TiO2<Ru/Ir/Ti. The role of various factors of RedOx processes that affect the degree of dye degradation, as well as chloride ions on the formation of active particles with high chemical energy at the moment of their formation, is discussed.