Methylene blue removal from aqueous solutions by electrocoagulation in continuous flow reactor: Modeling and optimization of operating parameters

Introduction The application and increasingly produce of colorants, particularly, synthetic dyes, are one of the main environmental and health concerns especially in industrialized countries. If this type of dyes is discharged into the environment without any control, many problems will arise. Therefore, it is necessary to remove the dyes from aqueous solutions using appropriate methods. The purpose of this study was to investigate the use of the electrocoagulation process to remove methylene blue as one of the most widely used and problematic dyes from aqueous solution. Methods & Materials This study was conducted using a lab scale electrocoagulation reactor operating at a continuous flow. To better analyze and set the minimum reasonable number of experimental runs, the study was carried out using response surface methodology using the Box-Behnken model. For better understanding, the process, the effect of operating variables and their interactions on the process performance was also analyzed using the model. For this purpose, three independent parameters (at three levels) including current density (5, 7.5 and 10 mA/cm 2), dye concentration (50, 100 and 150 mg/L) and operating time (20, 60 and 100 min) were used. Results ANOVA test results showed that dye removal was affected by all independent variables and their interactions (P<0.05). In optimal conditions, in the range of the levels of the selected variables, the current density of 39.7 mA/cm2, dye concentration of 21.23 mg/l and reaction time of 86.47 min the removal of methylene blue obtained 99.16%. Conclusion This study showed that in the optimal operating conditions, the process can effectively remove the methylene blue dye. This method can be examined and considered for a real scale condition because of its simple application and affordable.