Layered Titanates (Na2Ti3O7 and Cs2Ti5O11) as Very High Capacity Adsorbents of Cadmium(II)

A layered cesium titanate (Cs2Ti5O11) and a layered sodium titanate (Na2Ti3O7) were used to concentrate Cd(II) ion from aqueous solution. The reaction of aqueous solutions of cadmium(II) acetate with the cesium titanate was examined at room temperature under varied pH. An H type adsorption isotherm was obtained, indicating strong interactions between Cd(II) and the titanate. For the reaction of the sodium titanate with aqueous solutions of cadmium(II) acetate, the formation of cadmium carbonate was observed in addition to the ion exchange of Na2Ti3O7 with Cd(II). The maximum amounts of the collected Cd(II) were 1.28 mmol/g Cs2Ti5O11 and 1.16 mmol/g Na2Ti3O7, which were superior to the values (0.08-0.39 mmol/g adsorbent) reported for other inorganic ion exchangers such as clay minerals and zeolites.