Decolorization of methylene blue by the electro-Fenton process using stainless steel mesh electrodes

Abstract

Aim: In this study, the decolorization of methylene blue (MB) by the electro-Fenton process using stainless steel (SS) mesh electrodes was examined. Materials and Methods: The effects of initial dye concentration, pH, and ratio of Fe: H 2 O 2 , current density, and type of electrode were studied. The kinetics of the reactions was also studied. Results: The highest removal rate 99%was obtained at pH 3 within 20 min. Kinetics experiment studies showed that removal of dye was faster at lower initial dye concentrations. The results revealed that color removal was highest at a Fe 2+ :H 2 O 2 ratio of 1:4. An increase in current density resulted in an increase in oxidation rate and faster removal of color. The results demonstrated that increasing the size of the mesh pores led to an increase in the percentage of dye removal. The highest removal percentage (94.5%) was observed in 25 min with a mesh 2 electrode. The constant rate of dye removal on steel mesh 2 was 6.6 times higher than a steel plate. Energy consumed in this state was = 1.6 kWh/m 3 , compared to 2.6 kWh/m 3 under other conditions. Conclusion: Using SS mesh electrodes was very effective in color removal for MB under optimal conditions. The present study showed that increasing the steel mesh size improved the conditions for color removal and reduced the energy consumption. Therefore, it is suggested that steel mesh be used as an electrode for electrochemical processes.