Comparative Electrochemical Decolorization of Four Textile Dyes Using Six Electrode Materials

This study systematically compared six electrode materials: BDD, MMO, graphite, aluminum, iron, and titanium for the electrochemical treatment of aqueous solutions containing CR, NGB, Rh B, and MB. The dye concentration (10 mg L−1), supporting electrolyte (0.25 M NaCl), and nominal current density (13.0 mA cm−2) were kept constant, while electrode geometry, total current, and operating voltage differed among systems. Maximum decolorization efficiencies of 31–99.5% were observed after 60 min. BDD, MMO, and graphite produced the highest decolorization of CR, Rh B, and MB, whereas NGB was the most resistant dye (31–42%). Estimated specific electrical energy consumption at 60 min was approximately 12–15 kWh m−3 for BDD, 2.22–2.96 kWh m−3 for MMO, 3.46–4.33 kWh m−3 for graphite, 4–6 kWh m−3 for aluminum and iron, and 28–30 kWh m−3 for titanium. Because UV–Vis absorbance primarily reflects loss of chromophoric structures, the results are interpreted as decolorization rather than proof of complete degradation or mineralization. Graphite therefore represents a promising low-cost candidate for further evaluation, particularly with respect to durability, mineralization, transformation products, and performance in real textile wastewater.