Solid phase extractive preconcentration of some actinide elements using impregnated carbon

Apricot stone shells were carbonized under certain chemical and thermal conditions. The produced sorbent had been impregnated with different concentrations of oxalic and succinic acids. They were physically characterized and used for preconcentration of U(VI) and Th(IV) from acidified aqueous solutions. Batch equilibrium studies revealed that a quantitative preconcentration could be achieved at pH ∼2 for U(VI) and ∼1.3 for Th(IV). The equilibrium time was extended up to 24h for U(VI) and 40 min for Th(IV). The modified sorbent showed a superior extractability for U(VI) and Th(IV) with distribution coefficient mean values of 2084 and 7808 mL g-1, respectively. The sorption capacity values are 2.39 and 8.47 mg g-1 for U(VI) and Th(IV) sorption onto apricot stone anchored with oxalic acid and 2.3 and 9.18 mg g-1 for sorbent anchored with succinic acid. Desorption of loaded uranium ions was effectively achieved using 1 M HNO3 while only 0.5 M HNO3 was recommended to release retained thorium ions. (author)