Heteropoly acid salt inorganic ion adsorbent which has good adsorption performance for alkali metal ions could be used for the separation or extraction of rubidium. A spherical composite adsorbent AWP-CaALG was prepared by sol-gel method with calcium alginate (CaALG) and ammonium tungstophosphate (AWP) which were as carrier and active component

respectively

and characterized by SEM

XRD

IR analysis. The adsorption capacity of the adsorbent toward rubidium was determined to be 43 mg·g-1 under the optimum preparation conditions of m(NaALG):m(AWP)=1:2 and concentration of CaCl2 of 0.5 mol·L-1 with aging for 24 h and being dried at 105℃. The research of thermodynamic was carried out using Langmuir isotherm model and Freundlich isotherm model for description of experimental data. The free energy (ΔG)

enthalpy (ΔH) and entropy (ΔS) changes of adsorption were evaluated. The result showed that the process of adsorption of Rb+ by AWP-CaALG could be described by Freundlich equation. The adsorption of Rb+ was spontaneous and exothermic process

and therefore

low temperature was advantageous to the adsorption. The study of kinetic was conducted using pseudo-first-order kinetic model

pseudo-second-order kinetic model and shell progressive model for description of kinetic data. The result showed that the adsorption of Rb+ could be described by the pseudo-second order kinetic model and was controlled by the chemical reaction.