Performance Evaluation of Electrocoagulation Process in Removal of Anionic Dye and Cationic Dye From Aqueous Solution

Dye-laden wastewater released from industries is a critical source of water pollution. Although electrocoagulation (EC) is widely used for dye-containing wastewater treatment, its performance can vary depending on dye characteristics, particularly ionic nature. This study evaluates the EC treatment of two dyes with opposite ionic charges: anionic Congo red (CR) and cationic Methylene blue (MB), using aluminium electrodes. The effects of initial dye concentration (10–50 ppm), current density CD (5–25 mA/cm²), pH (5–9), NaCl dosage (0.25–1.25 g/L), and contact time (10–60 min) were investigated. Under optimum conditions, CR achieved 90.5% removal at a CD of 5 mA/cm², NaCl dosage of 1 g/L, contact time of 30 min, pH 7, and initial concentration of 40 ppm. MB achieved 43.4% removal at CD of 7.5 mA/cm², 1.25 g/L NaCl, 50 min, pH 8, and initial concentration of 10 ppm. Kinetic analysis indicated pseudo-second-order behaviour for CR (R² = 0.9939) and pseudo-first-order behaviour for MB (R² = 0.921). SEM, EDX, FTIR, and XRD analyses of the generated sludge revealed differences in their removal mechanisms. The operating costs were $0.755/m³ for CR and $1.523/m³ for MB . Overall, the findings demonstrate that dye ionic nature influences removal efficiency, treatment requirements, and operating cost during EC treatment.