Investigation into the extraction speciation of rare-earth radioisotopes from aqueous solution using polyoxometalates

► α2-P2W17O6110− can extract radioactive 153Sm and 177Lu from nitric acid solutions. ► 177Lu is more readily extracted than 153Sm at 0.5:1 and 1:1 α2-P2W17O6110−:Ln ratios. ► 31P NMR, excitation spectroscopy and radio-TLC probe extraction speciation. ► The complex speciation is governed by a combination of concentration and pH. ► At pHs of 0-1, 1:1 (Ln:α2-P2W17O61)7− forms solely at all stoichiometric ratios.