Gregory R. Choppin Florida Stote University Tollohassee
Ion Exchange Studies of the Actinide Elements
A
review of the actinide elements and ion exchange divides itself logically into one section considering the elements with atomic number 89 through 94, i.e., Ac, Th, Pa, U, Np, and Pu and another section covering the tripositive trans-plutonium elements. The ion exchange studies of the first group (Ac-Pu) have been discussed by Hyde (1) in his 1955 Geneva Conference paper and more recently by Katz and Seaborg - (.2.) and will only he briefly reviewed a t this time. Unlike Pa, U, Np, and Pu, actinium and thorium do not form anionic chloride complexes to any appreciable extent. Their separation from other elements, therefore, is achieved by use of Dowex-50 cation resin exchanger. Both Ac(II1) and Th(IV), because of their charge and size, will adsorb on Dowex-50 very strongly. The elution behavior of actinium as a function of hydrochloric acid concentration has been reported by Diamond, Street, and Seaborg (3). Like actinium, thoriunl elutes very slowly in either hydrochloric or nitric acid of any concentration. Both actinium and thorium may he removed from cation resin as chelate complexes by strong ammonium citrate or lactate solutions as reported by McLane and Peterson (4) and Asaro, Presented a8 part of the Symposium on Inorganic Chemists in the Xurlear Age before thc Division of History of Chemistry and Division oi Inorgrtnie Chemistry at the 134th Meeting of the American Chemical Society, Chicago, September, 1958.
462
/
Journal of Chemical Education
Stephens, and Perlman ( 5 ) . Adsorption of thorium on anion resin from 8 .If nitric acid has been used by Kraus and Nelson in separations from U(V1) (6). Separations involving protactinium, uranium, neptunium, and plutoilium are most effective with anion exchange resins since the different complexing po~r-ers of the several oxidation states of these elements allow a wide variation in anionic complex formation, Table 1 summarizes the behavior of these elements vith hydrochloric acid. Table 1.
Adsorption of Pa, U, Np, and Pu from Hydrochloric Acid on Dowex-1 Anion Exchange Resin
tion state
Pa
111 IV
... ...
V
Strong above Urn
VT
. ..
U
Yp
Pn
. ..
None Strong above 9
