Performance of a 3D uni-centered iron mesh electrocoagulation–electroflotation reactor for reactive turquoise blue dye removal: Effects of electrode configuration and operating parameters

This study developed and evaluated a uni-centered iron mesh electrocoagulation/electroflotation (EC/EF) reactor operated in monopolar-parallel mode for treating synthetic textile wastewater containing Reactive Turquoise Blue. Baseline experiments were performed at 25 ppm dye concentration and 1.0 cm inter-electrode spacing to investigate the effects of applied voltage ((10–30 V), agitation speed (100–250 rpm), initial dye concentration (25–125 ppm), inter-electrode distance (0.5–1.5 cm), and electrolysis time (5–30 min) on simultaneous color and COD removal. The optimum operating conditions were identified as 25 V, 250 rpm, 75 ppm, and 1.5 cm for 30 min, at which 99.99% color removal and 97.22% COD removal were achieved. At the same time, the treated effluent showed final TDS and conductivity values of 54 ppm and 114 µS/cm, respectively. The 1.5 cm spacing was selected as the most practical configuration because it maintained excellent treatment performance while reducing electrical contact events and passivation-related instability compared with narrower gaps. Kinetic analysis showed that the first-order model best described both color and COD removal, with R 2 = 0.9563 and R 2 = 0.9697, respectively, indicating that it adequately represented the overall apparent removal behavior of the EC system under the selected conditions. Preliminary dye characterization using UV-Vis spectrophotometry, FTIR spectroscopy, and EDX analysis confirmed the dye's spectral and compositional features. In contrast, FTIR and XRD analyses of the generated scum revealed the formation of iron-based coagulating phases. The XRD reflections at 30.1°, 35.5°, 43.1°, 53.5°, 57.0°, and 62.6° were consistent with magnetite Fe3O4, indicating that the collected solids were not purely amorphous but contained a magnetite-dominant crystalline iron phase. Overall, the results demonstrate that the proposed uni-centered reactor provides a compact and efficient EC/EF configuration for textile wastewater treatment through the combined action of in situ generation of iron species, floc development, and flotation-assisted separation.