Separation of Plutonium-238 from Fission Products by Solvent Extraction Using HDEHP

Abstract

A procedure for separating rAaPu from a Np sample irradiated with neutrons is described. Rapid separation of Pu by HDEHP solvent extraction was attempted, and without adjusting its valency states in the dissolver solution of the sample. Both Pu(N) and Pu(VI) were extracted along with Np from the HNO. solutions of various concentrations. The Pu and Np extracted in the organic solution were backextracted with oxalic acid solutions. The decontamination factors of the crude products were of the order of lo2 for gross r-activity. The Pu in the products was separated from Np by means of ion exchange resin columns. Approximately 0.5 mg of 2 a s P~ was obtained with an efficiency exceeding 95%.

Theoretical studies on the AnO2n+(An = U, Np; n = 1, 2) complexes with di-(2-ethylhexyl)phosphoric acid

“…1) is one of the most widely used acidic organophosphorus extractants in the large-scale separation of f-element cations and has been extensively studied. [7][8][9][10] It has been found that HDEHP possesses high separation factors for adjacent lanthanide pairs 11 and can be infinitely mixed with organic diluents with the main form of hydrogen-bonded dimers in bidentate coordination mode to the metal cations. [12][13][14][15][16] In addition, HDEHP is a liquid cation exchanger used for back extraction in the CTH (Chalmers Tekniska Högskola) process.…”

Investigation of Pu(IV)-acetohydroxamic acid complex by solvent extraction with di(2-ethylhexyl) phosphoric acid

“…However, this dependence has not been experimentally reported for plutonium. Studies [17][18][19][20] were unable to derive an extraction constant for the extraction of plutonium by HDEHP because Pu 4+ has a higher tendency to hydrolyze and disproportionate at pH > 0. Peppard et al [21] was able to quantify this equilibrium for Th(IV) in perchloric and hydrochloric systems.…”

“…These studies have also noted that HDHEP is in a dimeric form in dilute organic solutions. Studies on the extraction of plutonium [17][18][19][20] by HDEHP show high distribution ratios at low acid concentrations. At pH ≥ 0, DEHP undergoes a proton exchange reaction with metal cations by forming an extractable chelate complex while rejecting the released proton to the aqueous phase.…”