Pulsed electrochemical oxidation of acid Red G and crystal violet by PbO2 anode

Abstract

Present work investigates the application of pulsed electrochemical oxidation technique using DSA anode, titanium coated with PbO2layer, for degradation of Acid Red G (anionic dye) and Crystal Violet (cationic dye). Decolorization efficiency, COD and TOC removal efficiency were measured and contrasted by varying process parameters such as current density, initial organic concentration, pulse frequency, pulse duty cycle and NaCl dosage. Furthermore, decay kinetics for color and COD removal process, average current efficiency and energy consumption were evaluated under diverse arguments. The results indicated that current density, pulse duty cycle and NaCl dosage exerted a positive influence on the performance of pulse electrochemical degradation for ARG and CV, namely, with the growth of relevant influencing factors, the corresponding removal efficiency, kinetic constant of decolorization and COD removal reaction, and specific energy consumption increased accordingly, whereas the average current efficiency gradually decreased. However, the initial concentration of ARG and CV had a negative influence on the pulse electrochemical degradation process, that is, with the increase of initial dye concentration could lead to the reduction of the corresponding removal efficiency, kinetic constant of decolorization and COD removal reaction and energy consumption, on the contrary, the average current efficiency went up. Being different from ARG degradation process, there were some substances adhering to the cathode during CV electrochemical degradation process due to its positive charge. Under same conditions, the degradation indexes of pulse constant current power supply mode were better than those of direct constant current mode, which was coincident for both ARG and CV.