Plutonium(IV) Extraction from Nitric Acid Solutions by Mixtures of Long-Chain Ammonium Nitrates

Abstract

SummaryThe liquid-liquid extraction of tracer amounts of Pu(IV) from 0.5 and 3 M nitric acid solutions by a mixture A + B, of two quaternary ammonium nitrates of a high molecular weight, or of one such nitrate with a long-chain tertiary amine nitrate in chloroform and in the octanol containing solvents n-dodecane or o-xylene has been studied.The Pu(IV) distribution coefficientsThe extracting agents used are: trilaurylamine (TLA), trilauryl-methylammonium nitrate (TLMA) and hexadecyl-dimethyl-benzyl ammonium nitrate (HDDMBA).Thermodifferential molecular weight determinations of quaternary ammonium nitrates and their Th(IV) and U(VI) nitrate complexes in benzene show a higher degree of association for the metal complexes than for the extracting agents. By saturation of solutions of different quaternary ammonium nitrates in benzene with Th(NO

The Influence of the Complex Formation between Octanol and Long-Chain-Quaternary Ammonium Nitrates in o-Xylene and n-Dodecane on the Extraction of Pu (IV)

“…From such trial plots for each of the different experimental series in the system TLMA/o-xylene/octanol, the average values of ki have been determined from the intercepts of the asymptotes to the log-log curve of (C^Qd -1 -1) versus [OJ with the ordinate as KQO = 28 ± 0. 5 and KQOT = 1900 ± 50 M" 4 .…”

“…Tertiary alkylamines of high molecular weight dissolved in hydrocarbon diluents have been widely studied as extracting agents [1], Recently, quarternary ammonium compounds have shown even more favourable characteristics with respect to plutonium recovery [2, 3, 4], Technical extraction processes for the separation of plutonium from uranium and fission products make use of selective extraction of plutonium(IV) from an aqueous phase of about 3 M nitric acid into an organic phase, followed by back-washing into an aqueous solution. As extracting agents tertiary amine nitrates of the type R'R"R"'NH · N0 3 (R', R", R'" represent aliphatic hydrocarbon chains with C 6 -C 24 ) and quaternary ammonium nitrates, Q's, of a rather similar structure like triauryl-methyl-ammonium nitrate, TLMA, or hexadecyl-dimethyl-benzyl-ammonium nitrate, HDDMBA, can be used [5]. In 3-4 M nitric acid the main Pu(IV) species is PU(N0 3 ) 3 + [6-9], although BBOTHEBS et al stated that in I-i M aqueous nitric acid, Pu(IV) is present as undissociated Pu(N0 3 ) 4 [10].…”