Separation of Transplutonium Elements by Phosphonate Extraction

A process for separating transcurium elements from americium and curium was developed and tested in laboratory scale experiments. This separation is based on preferential extraction of the transcurium elements into 2-ethylhexylphenylphosphonic acid [2-EH(P)A] from dilute hydrochloric acid solutions. Single-stage separation factors between californium and curium are as great as 100. Extraction positions of the transplutonium elements are americium < curium ≪ berkelium < californium < einsteinium < fermium. Distribution coefficients are directly proportional to the cube of the extractant concentration in the solvent and inversely proportional to the cube of the acid concentration in the aqueous phase over the range from 1 to 4 N.