Electrochemical degradation of methylene blue using electrodes of stainless steel net coated with single-walled carbon nanotubes

Abstract

In the present study, an electrochemical technique was used for degradation of methylene blue (MB) from aqueous solutions on a laboratory scale using a homemade plexiglass cell. Electrodes comprising a stainless steel net coated with single-walled carbon nanotubes (SWCNTs@SSN) were used as both the anode and the cathode. The effects of various parameters, including the supporting electrolyte type, solution pH, electrochemical time, applied voltage, electrolyte concentration, and initial MB concentration, on the MB decolorization efficiencies were investigated. The percentage of chemical oxygen demand (COD) removal was also investigated. The supporting electrolyte type, applied voltage, and electrolyte concentration have obvious effects on the degradation of MB, and the solution pH and initial MB concentration have minor effects on the degradation. As the initial MB concentration was varied from 100 to 400 mg L−1, the percentages of COD removal of all the investigated solutions were higher than 86.0%, and the general current efficiency (GCE) increased from 1.79 to 6.38%. The electrical energy consumption (Ec) increased with increasing applied voltage. The results of the study prove that the method is a potential technique for the treatment of azo dye wastewater.