Extraction of Strontium from HLLW using N,N,N′,N′‐Tetraisobutyl 3‐Oxa‐Glutaramide

The properties of N,N,N′,N′‐tetra‐isobutyl‐3‐oxa‐glutaramide (TiBOGA) to extract Sr2+ were investigated. The effect of diluents on the extraction of Sr2+ was studied using kerosene, 1‐octanol, toluene, and chloroform. Considering the formation of the third phase, and increase of D Sr, the distribution ratio of Sr2+, the mixture of 40/60 (V/V)% 1‐octanol/kerosene (KO) was chosen as the diluent in experiments. The dependence of D Sr on the concentration of TiBOGA in the organic phase and on the activity of NO3 − in the aqueous phase suggested the extracted complex to be Sr(TiBOGA)3(NO3)2 in the organic phase. The thermodynamic parameters were calculated from the dependence of the extraction constant (K) on temperature. The calculated values of K, ΔG 0, ΔH 0, and ΔS 0 are 1.04×103, −17.1 kJ mol−1, −48.9 kJ mol−1, and −107 J mol−1 K−1, respectively. Separation of Sr2+ from a simulated acidic high level liquid waste (HLLW) was carried out using 0.2 mol/L TiBOGA in 40/60% 1‐octanol/KO as organic phase. The results indicate that TiBOGA has good selectivity for Sr2+ over other metal ions in the simulated acidic HLLW. The separation factor (SF) for Sr2+ over other metal ions are >4×103 except with Ba2+ which is 129.