Treatment of reactive black 5 (RB 5) Dye using electrochemical advance oxidation processes (EAOP’s)

Abstract

Decolorization and degradation of the Reactive Black 5 (RB 5) has been studied using indirect electrochemical oxidation processes of electro-chlorination and electro-Fenton with graphite and carbon fiber electrodes. The process parameters studies have been done using RSM, Central Composite Design matrix with application of statistical analysis of model along with ANOVA and 3-D response surface graph. Electro-Fenton degradation and decolorization of RB 5 have been studied for pH, catalyst concentration, current applied and distance between the electrodes. The optimized values for various parameters were pH= 5, Catalyst concentration =.40mg/L, Current =342 mA and Distance =3.1cm with experiment results of 89.0% and 68.0% for decolorization and degradation respectively. The carbon cloth electrode gave the 95% dye decolorization and 70% degradation for optimal conditions and similar results were seen with carbon reinforcement with decolorization~ 93% and 67% degradation. However the resistance offer by both of them was higher than the normal electrodes. Electro-chlorination degradation and decolorization of RB5 was studied for pH, current applied and distance between the electrodes. The optimum operational parameters values by RSM were pH= 4.5, Current =381 mA and Distance =1.5 cm. The corresponding values of experiment results were 93% and 68 % for dye decolorization and degradation respectively. Combination of electro-Fenton and electro-chlorination was also carried for checking the enhance activity for decolorization and degradation. The operating parameters were catalyst amount of.40mg/L, Current at 381 mA, pH 4.5, and Distance between the electrodes as 1.5 cm. The complete Decolorization was observed in 30 minutes of reaction. The amount of dye degradation also saw increment as more than 79% was observed after 40 minutes of reaction. Carbon as cathode is extremely effective for production of H2O2 in presence of physically adsorbed air. In case of anode the carbon is not that effective due low stability, however it is effective for regeneration of Fe3+ to Fe2+. Electro Chlorination using carbon electrode is potent as formation potential of Chlorine reactive species is lower than it’s the oxygen evolution potential. Carbon electrodes as anode have stability issues near oxygen evolution potential.