Decolorization Treatment of Copper Phthalocyanine Textile Dye Wastewater by Electrochemical Methods

Abstract

Electrochemical decolorization and degradation treatment of aqueous copper phthalocyanine reactive dye solutions was comparatively studied by electrocoagulation, electrooxidation and electro-Fenton processes. In the electrocoagulation process with aluminum electrodes the colored aqueous solutions of initial pH 6.4 containing 50 mg L-1 copper phthalocyanine and 6 g L-1 NaCl were treated at applied current densities of 2.5 and 5 mA cm-2. Fast and 100% decolorization was achieved in 4 and 2 minutes of electroprocessing respectively. The indirect electrooxidation process was conducted in acidic electrolyte solutions containing 50 mg L-1 copper phthalocyanine and 6 g L-1 NaCl with Ti/Pt and graphite plate electrodes at the applied current density of 10 mA cm-2. Even after 90 minutes of electrolysis time the dye remained by 23 and 18.8 % respectively undegradable. By the direct and indirect electrooxidation with the same amount of Na2SO4 electrolyte and added H2O2 respectively and using the same electrodes, the copper phthalocyanine dye was not or was only barely degraded respectively. In the electro-Fenton process with Fe electrodes and added amounts of H2O2 at pH 3 and an applied current density of 5 mA/cm2 complete degradation of copper phthalocyanine occurred in 15 minutes.