Dissymmetric N,N-dialkylamides, the synthesis thereof and uses of same

Patent metadata

Field	Value
Publication number	US-10252983-B2
Application number	US-201615748030-A
Country	US
Kind code	B2
Filing date	Jul 28, 2016
Priority date	Jul 29, 2015
Publication date	Apr 9, 2019
Grant date	Apr 9, 2019

Abstract

Novel dissymmetric N,N-dialkylamides which meet the following formula (I):

where R represents a linear or branched alkyl group at C 8 to C 15 . A method for synthesizing these N,N-dialkylamides, and to the uses of same as extractants, alone or in admixture, in order to extract uranium and/or plutonium from an aqueous acid solution, or to totally or separate uranium from plutonium from an aqueous acid solution and, in particular, an aqueous solution resulting from dissolving spent nuclear fuel in nitric acid. Further, a method for processing an aqueous solution resulting from the dissolution of a spent nuclear fuel in nitric acid, allowing the uranium and plutonium contained in the solution to be extracted, separated and decontaminated in a single cycle, without requiring any plutonium reduction operation, and in which one of the aforementioned N,N-dialkylamides or a mixture of same is used as extractant. Applications for the method include the processing of spent nuclear fuels, in particular comprising uranium (e.g. UOX) or uranium and plutonium (e.g. MOX).

First claim

What is claimed is:

1. An N,N-dialkylamide of formula (I):

where R is a linear or branched alkyl group having 8 to 15 carbon atoms.

2. The N,N-dialkylamide of claim 1 , wherein the alkyl group comprises no more than 12 carbon atoms.

3. The N,N-dialkylamide of claim 2 , wherein the alkyl group is an n-octyl, n-decyl, n-dodecyl, 2-ethylhexyl or 2-ethyloctyl group.

4. A method for synthesizing an N,N-dialkylamide of formula (I):

where R is a linear or branched alkyl group having 8 to 15 carbon atoms, comprising a reaction of a halide of formula (II):

where X is a halogen atom, with an amine of formula HN(CH 3 )R where R is a linear or branched alkyl group having 8 to 15 carbon atoms.

5. A method for extracting uranium(VI) and/or plutonium(IV) from an acid aqueous solution, comprising at least one contacting of the acid aqueous solution with an organic solution comprising an N,N-dialkylamide or mixture of N,N-dialkylamides of formula (I):

where R is a linear or branched alkyl group having 8 to 15 carbon atoms, as extractant in an organic diluent, followed by a separation of the aqueous solution from the organic solution.

6. The method of claim 5 , wherein the organic solution comprises from 1 mol/L to 2 mol/L of the N,N-dialkylamide or mixture of N,N-dialkylamides.

7. A method for separating totally or partially uranium(VI) from plutonium(IV), uranium(VI) and plutonium(IV) being in an acid aqueous solution, comprising the following steps:
a) a co-extraction of uranium and plutonium from the aqueous solution, the co-extraction comprising at least one contacting of the aqueous solution with an organic solution comprising an N,N-dialkylamide or mixture of N,N-dialkylamides of formula(I):

where R is a linear or branched alkyl group having 8 to 15 carbon atoms, as extractant in solution in an organic diluent, followed by a separation of the aqueous solution from the organic solution;
b) a stripping of plutonium, in oxidation state +IV, and of a fraction of uranium from the organic solution resulting from step a), the stripping comprising at least one contacting of the organic solution with an aqueous solution comprising from 0.1 mol/L to 0.5 mol/L of nitric acid, followed by a separation of the organic solution from the organic solution; and
c) an extraction of all or part of the uranium fraction contained in the aqueous solution resulting from step b), the extraction comprising at least one contacting of the aqueous solution with an organic solution identical to the organic solution of step a), followed by a separation of the aqueous solution from the organic solution;

whereby there are obtained an aqueous solution comprising either plutonium without uranium, or a mixture of plutonium and uranium, and an organic solution comprising uranium without plutonium.

8. The method of claim 7 , wherein the organic solution of step a) comprises from 1 mol/L to 2 mol/L of the N,N-dialkylamide or mixture of N,N-dialkylamides.

9. The method of claims 7 , wherein the acid aqueous solution is an aqueous solution resulting from a dissolution of a spent nuclear fuel in nitric acid.

10. A single-cycle method for processing an aqueous solution resulting from a dissolution of a spent nuclear fuel in nitric acid, the aqueous solution comprising uranium, plutonium, americium, curium and fission products including technetium, the cycle comprising the following steps:
a) a co-extraction of uranium and plutonium from the aqueous solution, the co-extraction comprising at least one contacting, in an extractor, of the aqueous solution with a first organic solution comprising a N,N-dialkylamide or mixture of N,N-dialkylamides of formula (I):

where R is a linear or branched alkyl group having 8 to 15 carbon atoms, as extractant in solution in an organic diluent, followed by a separation of the aqueous solution from the organic solution;
b) a decontamination of the organic solution resulting from step a) with respect to americium, curium and fission products, the decontamination comprising at least one contacting, in an extractor, of the organic solution with an aqueous solution comprising from 0.5 mol/L to 6 mol/L of nitric acid, followed by a separation of the organic solution from the organic solution;
c) a partitioning of the uranium and plutonium contained in the organic solution resulting from step b) into an aqueous solution comprising either plutonium without uranium, or a mixture of plutonium and uranium, and an organic solution comprising uranium without plutonium, the partitioning comprising:
c 1 ) a stripping of plutonium, in oxidation state +IV, and of a fraction of uranium from the organic solution resulting from step b), the stripping comprising at least one contacting, in an extractor, of the organic solution with an aqueous solution comprising from 0.1 mol/L to 0.5 mol/L of nitric acid, followed by a separation of the organic solution from the organic solution;
c 2 ) an extraction of all or part of the uranium fraction contained in the aqueous solution resulting from c 1 ), the extraction comprising at least one contacting, in an extractor, of the aqueous solution with a second organic solution identical to the organic solution of step a), followed by a separation of the aqueous solution from the organic solution;

d) a decontamination of the organic solution resulting from c 1 ) with respect to technetium, the decontamination comprising:
d 1 ) a stripping of technetium, in oxidation state +IV, from the organic solution resulting from c 1 ), the stripping comprising at least one contacting, in an extractor, of the organic solution with an aqueous solution comprising from 0.1 mol/L to 3 mol/L of nitric acid and at least one reducing agent capable of reducing technetium from oxidation state +VII to oxidation state +IV, followed by a separation of the organic solution from the organic solution;
d 2 ) an extraction of the uranium fraction contained in the aqueous solution resulting from d 1 ), the extraction comprising at least one contacting, in an extractor, of the aqueous solution with an organic solution identical to the organic solution of a), followed by a separation of the aqueous solution from the organic solution;

e) a stripping of uranium from the organic solution resulting from d 1 ), the stripping comprising at least one contacting, in an extractor, of the organic solution with an aqueous solution comprising no more than 0.05 mol/L of nitric acid, followed by a separation of the organic solution from the organic solution; and
f) a regeneration of the organic solution resulting from step e); whereby a first and a second aqueous solution are obtained, decontaminated with respect to americium, curium and fission products including technetium, the first aqueous solution comprising either plutonium without uranium, or a mixture of plutonium and uranium, and the second aqueous solution comprising uranium without plutonium.

11. The method of claim 10 , wherein the organic solution of step a) comprises from 1 mol/L to 2 mol/L of the N,N-dialkylamide or mixtu

Assignees

• Commissariat Energie Atomique
• Areva Nc
• Orano Cycle

Inventors

• Miguirditchian Manuel
• Baron Pascal
• Lopes Moreira Sandra
• Milanole Gaëlle
• Marie Cécile

Classifications

• C22B60/026

  liquid-liquid extraction with or without dissolution in organic solvents · CPC title

• C22B60/04

  Obtaining plutonium · CPC title

• C07C231/02

  from carboxylic acids or from esters, anhydrides, or halides thereof by reaction with ammonia or amines · CPC title

• C22B60/0239

  nitric acid containing ion as active agent · CPC title

• C07C233/05 Primary

  having the nitrogen atoms of the carboxamide groups bound to hydrogen atoms or to acyclic carbon atoms · CPC title