RESIDUE ADSORPTION .3. MUTUAL SEPARATION OF 227AC, 227TH AND 223RA

227Ac, 227Th and 223Ra can be separated from each other with good yield and radiochemical purity by adsorption on platinum followed by selective desorption. The three nuclides are deposited on Pt by evaporation from aqueous HF, HNO3 or NH4NO3 solutions. The 223Ra is only partially soluble in H2O but can be quantitatively desorbed by dilute mineral acids or their ammonium salt solutions. Desorption with 0·01 N HF is preferred because it has the least tendency to disturb the 227Ac and 227Th fluorides in the residue. A fluoride residue containing 227Ac and 227Th can be leached repeatedly with 0·01 N HF to recover 223Ra; however, because of alpha recoil, about half of the ingrown 223Ra cannot be desorbed with dilute HF. Evidence is presented indicating that metathesis of the fluoride residue converts the Ac(III) to a double salt with ammonium nitrate. Elimination of the NH4NO3 by sublimation yields a basic 227Ac nitrate which can be desorbed by 0·1 N NH4NO3 but not by H2O. Under the conditions described, 227Th remains adsorbed as an oxide or basic nitrate, while 227Ac is quantitatively desorbed. © 1969.