Separation and extraction of cesium from salt lake brine by the calcium alginate-ammonium tungstophosphate composite adsorbent

A composite adsorbent calcium alginate-ammonium tungstophosphate (Ca(ALG)(2)-AWP) was synthesized by a sol-gel method using ammonium tungstophosphate ((NH4)(3)PW12O40) as the adsorption active component and calcium alginate (Ca(ALG)(2)) as the matrix. Adsorption and desorption behaviors of Li+, Na+, K+, Rb+, Cs+ and Mg2- were investigated at 25 degrees C comprehensively. Under competitive adsorption conditions, the separation factor was in the order of beta(Cs/Mg)>> beta(Rb)(/Mg) > beta(Li/Mg) similar to beta(Na/Mg) similar to beta(K/Mg) explained by considering the hydration radius of metal ions, electrostatic traction and Gibbs free energy. In the column tests, Cs+ exhibited the lowest breakthrough ratio and highest selectivity. High quality of CsCl with the content of 82.44 wt% was obtained from the salt lake brine after desorption by the mixed solution of 3 mol L-1 NH4Cl and 1 mol L-1 HCl. Therefore, the method of column adsorption-desorption by using Ca(ALG)(2)-AWP was promising to separate and extract Cs+ from the salt lake brine with high selectivity and excellent regeneration.