Kummert for g-Al 2 O 3 and Sigg for FeOOH developed an
The surface complexation model as previously applied to pure approach which considers the ligand exchange between acid anion and pure cation exchange equilibria has been extended to molecules and surface OH groups (13, 14). By means of the description of the amphotheric sorption of inorganic ions onto constants determined empirically, the approach allows the activated alumina. Logarithmic equilibrium parameters (generaldescription of sorption isotherms for single solutes at differized separation factors) can be calculated from equilibrium conent pH values and different concentrations. Numerous other centrations in simple systems for the sorption of anions and catauthors apply the surface complexation theory to determine ions. Both separation factors are functions of the oxide loading surface potentials or surface charge densities and to calculate composition. Plotting the separation factors vs the loading compotitration curves (e.g., 15, 16). A summary about the respecsitions yields a set of two sorption constants for each kind of ion.
The major advantage of the theoretical approach is that these tive work has been given by Balistrieri ( 17).
constants can be applied without any adaptation to the prediction
The great majority of these publications comprises basic of multicomponent systems. Evaluation of experiments with two physicochemical research which allows the understanding commercially available activated alumina products demonstrate of phenomena. From an engineering point of view, however, the validity of the approach. The equilibrium of multicomponent it seems worthwhile to try to attempt a prediction of equilibsystems can be predicted with excellent accuracy by means of the ria for simple and multicomponent sorption problems. A parameters for the uptake of chloride, nitrate, sulfate, sodium, promising way for such a prediction results from the applicaand potassium ions. ᭧ 1997 Academic Press tion of the surface complex formation theory, which is based