A series of selective ion-exchangers was synthetized, containing phosphinic or phosphonic acid functional groups. The selective
sorption of Sc3+, Fe3+, Ga3+, In3+, Al3+, La3+, Pb2+, Co2+ and Ca2+ ions in 0.1–4.0M HNO3 medium was investigated using a batch experiment technique. The selectivity of these exchangers generally decreased in the
order: Sc>Fe>In>Ga>Al>La>Pb>Cu>Co>Ca. The observed large differences in selectivity resulted in effective separation procedures
of scandium from lanthanides, and gallium (or indium) from bivalent elements. The selective separation of these ions from
their different mixtures is also possible.