(A) study on the characteristics of cobalt adsorption on prepared $TiO_2$ and Fe-Ti-O adsorbents in high temperature water

Abstract

A heat-resistant inorganic adsorbent for direct use to remove soluble corrosion products under reactor water conditions is attractive alternatives for water purification system in pressurized water reactors or boiling water reactors because of the limitations of organic ion-exchange materials in their use. Among the radioactive corrosion products particularly $^{60}Co$ is the primary source of growth in reactor radiation fields. A review of available information on potential adsorbent media was carried out. $ZrO_2$, $TiO_2$ and its mixed oxide were identified as materials suitable for the removal of dissolved corrosion products in high temperature water. Stable $ZrO_2$ spheres were prepared using sol-gel process from $ZrO(NO_3)_2$ $nH_2O$, and $TiO_2$ and Fe-Ti-O adsorbents were prepared by hydrolysis of $Ti(OC_3H_7)_4$ and alkalinizing an equimolar mixed solution of $TiCl_4$ and $FeCl_2$ followed by heat treatment of their hydroxides, respectively. Their structures were studied by X-ray diffractometer (XRD), thermogravimetric and differential thermal analysis (TG-DTA), BET method, and Fourier transform infrared (FT-IR) spectrometer. The $Co(NO_3)_2\cdot6H_2O$ was used for the $Co^{2+}$ stock solution, which is based on the thermodynamic solubility calculation in cobalt(II) nitrate - nitric acid system at high temperature. The cobalt adsorption characteristics of the adsorbent in high temperature water were investigated in a stirred batch autoclave containing the $Co^{2+}$ solution of $5\times10^-5$ mol/dm3. The prepared $ZrO_2$ spheres have a very low adsorption capacity. The prepared Fe-Ti-O adsorbent was found to be stable nonstoichiometric ferrous ferric titanium oxide with pseudobrookite and a small fraction of rutile structures. $Co^{2+}$ adsorption capacity of the Fe-Ti-O adsorbent was determined to have larger (0.38 meq $Co^{2+}$/g adsorbent at $280^\circ C$) than that of $TiO_2$ at high temperature. The enthalpy changes ($\Delta\,H^o$) of about 34 and ...