Characteristics of Cobalt Adsorption on Prepared TiO2 and Fe-Ti-O Adsorbents in High Temperature Water

Abstract TiO2 and Fe-Ti-O adsorbents were prepared by hydrolysis of Ti(OC3H7)4 and by alkalizing an equimolar mixed solution of TiCl4 and FeCl2, followed by heat treatment of their hydroxides. Their structures were studied by x-ray diffractometry and TG-DTA. The Co2+ adsorption characteristics of the adsorbent in high temperature water were investigated in a stirred autoclave. The prepared Fe-Ti-O adsorbent was found to be a stable nonstoichiometric ferrous/ferric titanium oxide with pseudobrookite and rutile structures. The Co2+ adsorption capacity of the Fe-Ti-O adsorbent was determined to be larger (0.38 meq Co2+/g adsorbent at 280[ddot]C) than that of TiO2 at high temperature. The enthalpy changes (ΔH[ddot]) of about 34 and 49 kJ·mol−1 due to the adsorption of Co2+ on the TiO2 and Fe-Ti-O adsorbents, respectively, indicates that the adsorption is endothermic in the experimental temperature range (150–280[ddot]C). It is shown that the specific surface areas of these adsorbents are not dominant factors ...