Comparison of removal of Acid Orange 7 by electrooxidation using various anode materials

This study investigated the color removal efficiency of Acid Orange 7 by electrochemical oxidation. The operating variables, such as the applied current density, the pH of solution, the temperature of solution, and the concentration of electrolytes, were investigated. Five materials were used to compare their efficiencies for removing the Acid Orange 7. The removal efficiency follows the order: ACF c > ACF b > ACF a > Pt/Ti > graphite. The color removal percentage increased when increasing the applied current density up to 10.0 mA/cm2, at which point the color removal rate began to be controlled by mass transfer. Experimental results showed that higher pH and temperature of the solution were beneficial for the removal of Acid Orange 7 and that the Na2SO4 electrolyte concentration did not significantly affect the removal rate. The energy consumption was in the range of 1.178 to 10.44 kWh/mol dm3, depending on the applied current density. The adsorption and electrooxidation were found to follow first-order kinetics. The best overall rate constant for ACF a was found to be 0.16 min− 1 at an initial pH of 9.7. The regeneration of ACF anode surface was observed after a 30-min treatment using 10.0 mA/cm2.