Influence of Supporting Electrolytes on Electrochemical Treatability of Reactive Black 5 Using Dimensionally Stable Anode

Dye wastewaters contain significant amounts of toxic organic species and intense color. Electrochemical oxidation has a proven potential to degrade these bio-resistant pollutants. This paper presents the results of indirect electrochemical oxidation of Reactive Black 5 (RB 5) recalcitrant dye wastewater using NaCl, KBr and Na2SO4as supporting electrolytes. The studies were performed in an undivided batch reactor using indigenously prepared Ti/CoOx–RuO2–SnO2–Sb2O5electrode classified as dimensionally stable anode (DSA). Characterization of the catalytic coating was performed using scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy-dispersive X-ray (EDAX) analysis. Similar operating conditions like electrolyte concentration, pH, current density and electrolysis time were used for all studies. The progress of dye degradation was monitored by estimating reduction in chemical oxygen demand (COD), total organic carbon (TOC) and color. Other performance indicators like average current efficiency (ACE) and energy consumption (EC) were also analyzed. The rate of COD removal followed pseudo-first-order kinetics. The present investigation exhibited highest treatment effectiveness in the presence of chloride compared to bromide and sulfate as degradation was dependent on the generation of highly electroactive oxidative species.