Anodic Degradation of CI Reactive Blue 221 Using Graphite and IrO2/TaO2/RuO2 Coated Titanium Electrodes

Anodic degradation of the biorecalcitrant reactive dye CI Reactive Blue 221 was investigated using graphite and IrO2/TaO2/RuO2 coated titanium electrodes in a batch reactor setup. The decolorization and mineralization of the dye molecule was monitored by UV−visible spectrophotometric method and chemical oxygen demand (COD) and/or total organic carbon (TOC) measurements, respectively. The effect of different electrolytes and applied current density on the mineralization of CI Reactive Blue 221 in the presence of different electrode materials was studied. Though both the electrode materials were found to be effective for decolorization, complete mineralization of the dye was accomplished in the presence of graphite over a pH range of 6.0−8.0. The efficiency of the electrode material was evaluated in terms of instantaneous current efficiency (ICE), electrochemical oxidizability index (EOI), and specific energy consumption (E sp). The metabolites formed during the degradation reaction were identified using GC-MS, and the degradation pathway was proposed.