Akademik Veri Yönetim Sistemi
Brazilian Journal of Chemical Engineering, 2025 (SCI-Expanded, Scopus)
In this paper, an electrochemical reactor using monopolar parallel-connected aluminum-iron electrodes was designed and color and COD removal was performed from reactive textile dye solutions: Reactive Orange 16 (RO16) and Reactive Red 239 (RD239). Electrocoagulation (EC) was selected as the removal method in this study due to its advantages over other electrochemical methods, such as ease of design and operation, low electrolysis time (ET) and sludge production, cost-effectiveness, and reduced likelihood of secondary pollutant formation due to the absence of additional chemicals. To optimize process performance, the effects of key operating conditions such as inlet pH, current density, conductivity, and initial dye concentration were investigated. In addition, some parameters, such as operating costs and the amount of sludge resulting from electrode consumption during the electrocoagulation process, were optimized, and the results are presented in this paper. In all studies, the stirring speed was 250 rpm, and the electrocoagulation duration was 20 min. Optimum experiment conditions for removal of RO16 dye solution pH:6 for Al electrode, current density 100 A/m2, conductivity 500 µS/cm; for the Fe electrode, pH: 8, current density 75 A /m2, conductivity 1000 µS/cm were obtained. When using Al electrode for RD239 dye solution pH:3, current density 100 A/m2, conductivity 250 µS/cm; for the Fe electrode pH 5, current density 75 A/m2, conductivity 500 µS/cm were obtained. For both dye solutions for Al and Fe electrodes, the color removal efficiency was approximately 98% at 50 mg/L initial dye concentrations. Better color removal was achieved at lower initial dye concentrations due to the insufficient amount of metal hydroxide required for good color removal at higher azo dye concentrations. As the initial dye concentration increased, COD and turbidity removal efficiencies decreased in parallel with color removal. When the total operating cost (energy + electrode) was evaluated in terms of solution volume, color removed, and COD, it was found that energy consumption for both dyes was lower for the Fe electrode and higher for the Al electrode. Under optimal conditions, the energy consumption for the Al and Fe electrodes in the EC process for RD239 removal was calculated as 8.61–6.13 kWh/m3, and for the Al and Fe electrodes in the EC process for RO16 removal was calculated as 6.15–8.72 Wh/m3. Experimental findings showed that as the electrolyte concentration increased, electrical energy consumption increased and, in parallel, floc production rate and dye removal efficiency also increased. In the EC process where RO16 removal was carried out, 2.22, 1.62 kg/m3 sludge was formed for Al and Fe electrodes in 300 mg/L dye solution under optimum conditions, respectively, and 0.86, 1.96 kg/m3 sludge was formed for RD239 removal under the same conditions, respectively. In the EC process where RO16 removal was carried out, 2.22 and 1.62 kg/m3 of sludge was formed for Al and Fe electrodes, respectively, in a 300 mg/L dye solution under optimum conditions. In the EC process where RD239 removal was carried out, 0.86 and 1.96 kg/m3 of sludge was formed for Al and Fe electrodes under the same conditions, respectively. Changes in pH, current density, and electrocoagulation time have affected sludge formation. The results indicate that Fe electrodes are more effective for color removal and economically advantageous, whereas Al electrodes achieve higher COD reduction. Optimized conditions were identified for each dye–electrode pair, providing practical guidance for industrial-scale wastewater treatment. The optimum conditions determined in the study and the performance comparison of the electrodes are a valuable guide for researchers in selecting the most appropriate electrode and operating condition for a particular textile wastewater.