The simultaneous removal of reactive and disperse dyes by Electrocoagulation Process with a bipolar connection of combined Iron and Aluminum electrodes: Experimental design and Kinetic studies

Abstract

<jats:p>This study concerns the ability of electrocoagulation process to remove simultaneously disperse and reactive dyes by using combined iron and aluminum electrodes in bipolar mode. A statistical experiment design (Response Surface Methodology: RSM) was adopted to model the process and to optimize the parameters influencing the removal efficiency of the dyes. The mathematical model is established, using a rotatable central composite design uniform to study the empirical relationships between two responses (Removal efficiency, energy consumption) and five factors: initial pH, current density, the concentration of supporting electrolyte, time and stirring speed. This treatment, therefore, led to a removal efficiency that can reach more than 95% with low consumption energy of 9 kWh/Kg of removed dye. Kinetic, isotherm adsorption and thermodynamic studies were undertaken with the optimized parameters. Electrocoagulation mechanism was modeled using adsorption kinetics and isotherm models, it is sited were on the insoluble iron and aluminum flocs. This study shows that the Freundlich model fit the adsorption isotherm, the kinetic of the electrocoagulation is better presented by the pseudo- second-order kinetic, the adsorption is endothermic and spontaneous for both dyes. Analysis of the sludge allowed quantifying the role of each electrode in removing dyes.</jats:p>