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−, SO42−, NO− anions and Na+, K+, NH4+ cations, were compared in terms of color removal efficiencies. The presence of SO42− 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. [Display omitted] •Electrolytes containing Cl−, SO42−, NO− anions and Na+, K+, NH4+ cations, were compared.•Electrolyte type significantly affected the performance of the electrocoagulation.•Supporting electrolyte performances changed significantly depending on the type of the electrode material.•Chloride containing electrolytes showed superior performances.