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 Co-Z+ adsorption capacity of the Fe-Ti-O adsorbent was determined to be larger (0.38 meg Co2+/g adsorbent at 280 degrees C) than that of TiO2 at high temperature. The enthalpy changes (Delta H degrees) of about 34 and 49 kJ . mol(-1) due to the adsorption of Co-Z+ on the TiO2 and Fe-Ti-O adsorbents, respectively, indicates that the adsorption is endothermic in the experimental temperature range (150-280 degrees C). It is shown that the specific surface areas of these adsorbents are not dominant factors for Co2+ adsorption on oxides at high temperature.