Characterization of anion exchange membranes fouled with humate during electrodialysis

Fouling tendencies during electrodialysis (ED) can be determined by the electrochemical and physical properties of the foulants and ion exchange membranes. In this study, the fouling characteristics of anion exchange membranes were investigated according to their electric resistances, hydrophobicities, exchange capacities and zeta potentials. In order to correlate the fouling potential with the properties of the foulant (humate), the zeta potential, molecular weight distribution and total acidity were measured. The fouling potentials in ED cells were compared based on the performances of ED experiments with 0.1 M NaCl containing 100 mg/l of sodium humate, showing that AMX had the lowest fouling potential while ACM the highest. Investigation of pH effects revealed that the ED performance increased at a pH value below the isoelectric point due to increased insoluble humate.