Use of alternating current for colored water purification by anodic oxidation with SS/PbO2 and Pb/PbO2 electrodes

Abstract

This paper suggests a new alternative for the acceleration of dye removal by adopting alternating current instead of direct current in the treatment of methylene blue solutions and industrials effluents, using anodic oxidation on Pb/PbO2 and stainless steel (SS)/PbO2 anodes. A comparative study of the influence of electrolyte support (NaCl, NaNO3, and Na2SO4) on the anodic oxidation performance and the anode stability was performed. The best results were obtained in presence of NaCl where the color removal percentage reached about 80.13% and 55.8%, for Pb/PbO2 anodes, and 89.5% and 60.4% for the SS/PbO2 anodes for alternating and direct current, respectively. Treatment in alternating current conditions enhanced the removal speed. Atomic absorption analysis confirmed the decrease of the release of (Pb2+) ions to much lower values compared with direct current and to those allowed by the Standards. LC/MS and phytotoxicity analyses confirmed the non-toxicity of the generated by-products during the anodic oxidation of methylene blue and the possibility of the reuse of the treated water.