Study on the adsorption–desorption behaviours of La 3+ , Sm 3+ , and Y 3 + by HEHEHP extraction resin in chloride medium

Abstract The adsorption–desorption behaviours of La 3+ , Sm 3+ , and Y 3+ on 2‐ethylhexylphosphonic acid mono‐2‐ethyl hexyl ester (HEHEHP) extraction resin were investigated in a chloride medium. The effects of reaction time, pH, hydrochloric acid concentration, flow rate, and adsorption mechanism were studied in detail using static and dynamic experimental methods. The results show that La 3+ is the first to reach adsorption equilibrium, followed by Sm 3+ and Y 3+ ; the highest adsorption capacities of La 3+ , Sm 3+ , and Y 3+ are obtained at solution pH of 4 and in the order of Y 3+ > Sm 3+ > La 3+ . La 3+ , Sm 3+ , and Y 3+ can be eluted by 0.3, 0.5, and 3 mol/L hydrochloric acid, respectively, indicating that La 3+ elutes most easily, and Y 3+ is difficult. Moreover, the flow rate has little effect on the peak of rare earth desorption. The adsorption process is chemisorption; the slope method indicates that for each mol Sm 3+ or Y 3+ ion adsorbed, 3 mol H + ions are simultaneously released, but two for La 3+ under the given pH conditions. It is expected to provide theoretical and technical support for preparation of ultra‐high purity rare earth by HEHEHP extraction resin.