Comparison of the effects of various supporting electrolytes on the treatment of a dye solution by electrocoagulation process

Laboratory experiments were conducted to investigate the effect of some supporting electrolytes on the treatment of Reactive Black 5 (RB5) by electrocoagulation using aluminum and iron electrode couples. Electrolytes, which contain Cl⁻, SO₄ ²⁻, NO⁻ anions and Na⁺, K⁺, NH₄ ⁺ cations, were compared in terms of color removal efficiencies. The presence of SO₄ ²⁻ led to poor performances with aluminum electrodes yielding a removal efficiency close to 45% at 8.33 A/m². Similarly, the presence of NO₃ ⁻ when iron electrodes were used adversely affected the process performance. The removal efficiency with KNO₃ was 49.1% at 8.33 A/m². Overall Cl⁻ containing electrolytes performed well achieving almost complete decolorization (99.9%) regardless of the electrode type. The performance of Al electrode considerably improved in the presence of NH₄ ⁺, achieving 98.0% and 99.1% removal efficiencies at the current densities of 4.17 A/m² and 8.33 A/m², respectively in 10 min treatment duration.