Characterization of the membrane charge of Al2O3 membranes

In order to characterize the membrane charge of the alumina membrane, we sa w about the information on the membrane charge at first. Then, we pointed o ut that the effective membrane charge of alumina consists of two parts. One part is the membrane charge due to the dissociation of the ionizable group s of membrane, and the other part is the membrane charge affected by the el ectrolytes in the bulk solution. Then, we proposed the new membrane model t hat is the combination of the selective ion adsorption model and the amphot eric membrane model. In this model, the effective membrane charge is determ ined by the dissociation of the ionizable groups of the membrane and the se lective adsorption of ions. We theoretically discussed the effect of the el ectrolyte concentration, the ionic species and the pH on the effective memb rane charge, Then, we showed that this new model, the advanced amphoteric m embrane model, can qualitatively explain the phenomena related to the membr ane charge. We applied the advanced amphoteric membrane model to the membra ne potential of alumina membrane and concluded that the effective membrane charge of the alumina membrane was determined by the dissociation of the io nizable groups and the adsorption of anions. (C) 2001 Elsevier Science B.V. All rights reserved.