Comparative Study of the Competitive Adsorption of Mg, Ca and Sr Ions onto Resins

Existing studies on the adsorption of alkaline earth metal ions have mainly focused on the adsorption of one alkaline earth metal ion. However, under natural conditions, alkaline earth metal ions usually co-exist. While separating them using an adsorbent, they compete with each other for adsorption onto the adsorbent. In this work, comparative and competitive adsorption of Mg, Ca and Sr ions onto four resins (D001, DJH003, LSC-100 and LSC-500) of sodium form were investigated in batch experiments at 25 °C. Our results showed that in all the experiments, the equilibrium point was attained in approximately 4 hours. In general, the pseudo-first-order model is more suitable to describe the adsorption kinetic data than the pseudo-second-order model. For both D001 and DJH003 resins, there are bigger differences in the adsorption amounts of Mg, Ca and Sr ions for the competitive adsorption than for the non-competitive adsorption. Under competitive adsorption conditions, the separation factor follows the order of...