SURFACE CHARACTERISTICS OF MAGNETITE IN AQUEOUS SUSPENSION

Surface characteristics of magnetite at 25 degrees C in aqueous suspen sions are systematically studied. The measured specific surface area a nd concentration of proton binding sites correspond well to the calcul ated values. Zeta potential of magnetite in the absence of multivalent cations exhibits positive values in acidic solution and becomes negat ive with increasing pH. pH(pzc) is about 6. In the presence of excess cations such as Fe2+ or Fe3+, specific adsorption takes place at the s urface of magnetite, which dramatically influences the value of zeta p otential. The concentrations of soluble Fe ions at pH about 4.5 increa se with solid concentrations of magnetite indicating some surface-rela ted reaction mechanisms. (C) 1998 Academic Press.