The amalgamation behavior of heavy elements—III Extraction of radium, lead and the actinides by sodium amalgam from acetate solutions

Abstract

This paper presents extraction yields of radium, lead and the actinides from Ac through No, with sodium amalgam from 7 M sodium acetate solutions. The extraction yield is shown to depend upon the amount of HCl added to 7 M sodium acetate solution before extraction. Californium, einsteinium, fermium, mendelevium, radium and lead are extracted with high yields (75–100 per cent relative to Cf), while the lower actinides, Ac, Th, Pa, U, Np, Am, Cm and Bk are extracted with low yield (below 10 per cent relative to Cf). The addition of oxidizing agents such as H 2O 2 or HNO 3 before extraction strongly suppresses the extraction, except in the case of lead. Investigation of the extraction behavior of all actinide elements (except lawrencium, which has no isotopes suitable for conventional chemical study) and a survey of the literature of the extraction behavior of the lanthanides show cases of uncorrelated extraction properties in both series. On the whole, however, high extraction yields correlate with independent evidence for the existence of a dipositive oxidation state in the lanthanides and suggest the possible formation of this oxidation state in californium and heavier actinides.