Study of cobalt adsorption on an oxygenated apatite surface

The aim of this study was to evaluate the effectiveness of the oxygenated apatite (OA) to adsorb cobalt cations in solution. The factors influencing the adsorption, such as initial concentration of the metal in solution, the pH and temperature of the medium, the ionic strength and the temperature of calcination were investigated. The tests of cobalt adsorption show that the fixed amount (32,2 mg/g) is important compared with other matrices adsorbent. This retention capacity increases with increasing the initial concentration of cobalt, the contact time and the adsorbent dose. The optimum pH of adsorption is 6,4 and the ionic strength of the medium has a negative influence on fixation rate of cobalt due to the competitiveness of the electrolytes present in solution with the metal towards the adsorbent active sites. With respect to the calcination at 900 ° C, it reduces the adsorbent power of the AO due to the increase of crystallinity degree and the disappearance of the hydrated layer of apatite. As regards the process of cobalt adsorption, it can be explained by the Langmuir and Freundlich isotherms