Removal of textile pollutants by electrocoagulation using all bipolar and monopolar connection mode of iron and aluminum composite electrodes

The present study deals with the treatment of synthetic effluents of the textile industry, containing a mixture of reactive and dispersed dyes by electrocoagulation process employing all bipolar and monopolar connections of Fe–Al composite electrodes. The performance of the process was evaluated through the analysis of color removal, consumption energy, turbidity, and chemical oxygen demand (COD). The serial mode in bipolar connection is more efficient than the monopolar mode. After the treatment, it was possible to remove 98% color removal, 98.5% turbidity, and 88% COD. Kinetics, thermodynamics, isotherm modeling for removal of textile dyes using electrocoagulation process were studied. The electrocoagulation reaction followed the first-order reaction kinetics, and also, Langmuir model fit the adsorption isotherm spontaneous for optimal connection mode of composite electrodes (Iron/Al). The exothermic and spontaneous nature of the adsorption process was confirmed. An electrochemical study is carried out to study the corrosion of aluminum and iron in the presence of the synthetic effluent. The influence of temperature on the mass loss of electrodes and flocs is remarkable, and this is in agreement with the results of SEM coupled with EDX analysis which confirms that the rate of presence of aluminum and iron in the floc increases with temperature. The extracted solution was analyzed by atomic absorption spectroscopy to evaluate the residual concentration of iron and aluminum, and the latter increased with temperature increasing.