Study of the electrocoagulation process using aluminum and iron electrodes

In this work, the electrocoagulation process using aluminum and iron electrodes has been used to treat synthetic wastewaters polluted with three different types of pollutant models: kaolin suspensions, dye solutions, and oil-in-water emulsions. It was obtained that both electrodes can achieve high efficiencies (above 80%) in the treatment of the three wastes. However, there are strong differences in the electrochemical coagulation or breakup mechanism that can be explained in terms of the speciation of the dissolved metals and especially in terms of the significant concentrations of monomeric and polymeric ionic species that appear in the treatment with aluminum electrodes. In every case, sweep coagulation explains the coagulation of kaolin suspension with both aluminum and iron electrodes. However, in the case of aluminum, the neutralization charge mechanism should also be considered for low reagent doses. The coagulation of EBT (Eriochrome Black T) solutions and the breakup of O/W emulsions (oil-in-water emulsions) have been explained by the binding of the pollutants to metal hydroxide precipitates. This binding is promoted for aluminum electrodes because of the adsorption of cationic reagent species on the surface of the aluminum hydroxide.This work was supported by the MCT (Ministerio de Ciencia y Tecnología, Spain) and by the EU (European Union) through Project CTM2004-03817/TECNO.Peer reviewe