Coupling of electrocoagulation and microflotation for the removal of textile dyes from aqueous solutions

[Display omitted] •Microbubbles were introduced in electrocoagulation cell via a microporous diffuser.•Addition of microbubbles improved the efficiency of electrocoagulation treatment.•The flotation rate of dye contaminants increased with the use of microbubbles.•Integration of microflotation with electrocoagulation reduced energy consumption. The aim of the present research was to examine the effect of applying air microbubbles in the conventional electrocoagulation cell. Iron electrodes were used for the electrocoagulation process and a microbubble diffuser was used to generate microbubbles for the integrated flotation process. The optimum value of each operating variable (i.e pH, current density, air microbubbles flow rate, and electrolysis/flotation time) was determined experimentally in order to provide the maximum removal efficiency by this system. It was demonstrated that the introduction of microbubbles into the electrocoagulation unit significantly enhanced the dye degradation efficiency due to their buoyancy and high surface area to volume ratio which help to quickly remove pollutants. Removal efficiency of 96 % was achieved with microbubbles compared to only 70.75 % by a no-bubbles based system under the same operating conditions of 6 min electrolysis/flotation time, pH 7, 2.5 ml/min air flow rate and 10 mA/cm2 current density. Results from the present work indicate that the combination of electrocoagulation with microflotation could be an effective and economic method for reducing the concentration of dissolved pollutants in water like dyes.