The removal of azo Acid Black 1, anthraquinone Reactive Blue 4, and xanthene Eosin Yellow using electrocoagulation with different types of cathodes was investigated. When a dye of 100 mg L−1, electric current of 0.3 A, and iron plate anode were used, dye removals using a steel wool cathode (591 cm2) were 1.8–4.4 times faster than those using an iron plate (28 cm2) or stainless steel plate cathode (28 cm2). Even though the total iron concentrations in the solutions for these two cathodes were close, the ferric concentration in the solution using a steel wool cathode was greater than that using a stainless steel cathode. An increase in electric current and mixing speed enhanced the dye removal using a steel wool cathode cell. Results of the Vibrio fischeri light inhibition test indicate that the decolorized solutions contained low toxicity of byproducts (23–35% light inhibition). When the steel wool cathode was washed with water for 30 s, the efficiency of the steel wool cathode reactor did not decrease during the first seven times of reuse.
