mina was measured under the same conditions for compari-Precipitation and adsorption of metal ions (Co(II), Ni(II), son. In the cases of Co (2, 3), Ni (12), Cu(II), and Cr(III)) on g-alumina were investigated experimenstrong interaction with alumina was reported, using different tally. A surface chemical reaction model to calculate concentratechniques (coprecipitation, EPR, ENDOR, XRD, DRS).
tions of aluminum ions, metal ions, and pH as variables depending
Thus the model calculations should be based on a surface on amount of alumina, volume of liquid and gas phase, initial complexation model and should allow the determination of metal concentration, and amount of acid or base added is prethe equilibrium constants of the system, starting from acid sented. In the case of Co(II) the pH dependence of rest concentraor base added to the system, as the reaction was too slow tions with and without alumina is equal; adsorption may be disre-(according to preliminary experiments) to adjust conditions garded. For the other ions adsorption is important. Considering the charge of the surface does not improve the fit. In the pH such as pH during the measurements. As a consequence the region, where adsorption leads to lower rest concentrations than model resembles that of Farley et al. (31) or the one used precipitation, adsorption may be described by a Henry isotherm. in MINTEQA2 (32) with respect to the treatment of equilib-