Electrodissolution of aluminum electrodes in electrocoagulation processes

The electrodissolution of aluminum electrodes in aqueous solutions containing sulfate or chloride ions is studied in this work. The results obtained are important in order to obtain a better understanding of the electrocoagulation process, as the electrodissolution of the anode surface is its first step. It has been determined that both chemical and electrochemical dissolution play an important role in the aluminum generation. The chemical dissolution of aluminum is strongly influenced by the pH. Alkaline pHs increase the dissolution rate by orders of magnitude. Within the experimental conditions used, the supporting media does not seem to influence greatly the chemical dissolution process. The electrochemical dissolution process depends mainly on the specific electrical charge passed. Salinity does not significantly affect the electrodissolution rate. Good fittings between experimental and modeled data are obtained by modeling the system with a simple model based on two assumptions: a highly segregated flow pattern and the calculation of aluminium species and pH from a pseudoequilibrium approach.