# US 2021/0332002 A1 · Dissymmetric n,n-dialkylamides used particularly for separating uranium(vi) from plutonium(iv), synthesis thereof and uses of same

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- Number: US 2021/0332002 A1
- Document ID: US20210332002A1
- Status: Published application
- Kind: A1
- Application number: 16/479,830
- Filed: 2018-01-25
- Published: 2021-10-28
- Earliest claimed: 2017-01-26
- Assignees: Commissariat A L'energie Atomique Et Aux Energies Alternatives; Orano Cycle; Electricite de France
- Applicants: Commissariat à L'éNergie Atomique Et Aux êNergies Alternatives; Orano Cycle; Electricite De France
- Inventors: Gaëlle Milanole; Emilie Russello; Cécile Marie; Manuel Miguirditchian; Christian Sorel
- Web page: https://patentgrep.com/patent/US20210332002A1

## CPC

- C07C 233/05: having the nitrogen atoms of the carboxamide groups bound to hydrogen atoms or to acyclic carbon atoms
- C22B 3/32: Carboxylic acids
- C22B 60/026: {liquid-liquid extraction with or without dissolution in organic solvents}
- C22B 60/04: Obtaining plutonium
- G21C 19/46: Aqueous processes {, e.g. by using organic extraction means, including the regeneration of these means}
- C07C 231/02: from carboxylic acids or from esters, anhydrides, or halides thereof by reaction with ammonia or amines
- Y02E 30/30: Nuclear fission reactors
- Y02P 10/20: Recycling
- Y02W 30/50: Reuse, recycling or recovery technologies
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C22B: PRODUCTION AND REFINING OF METALS (electrolytic C25); PRETREATMENT OF RAW MATERIALS
- G21C: NUCLEAR REACTORS (fusion reactors, hybrid fission-fusion reactors G21B; nuclear explosives G21J)
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02W: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT

## Abstract

A dissymmetric RN,N-dialkylamides of formula (I) in which: R1 represents a linear C1 to C4 alkyl, R2 represents a linear C1 to C10 alkyl, and R3 represents a linear or branched C6 to C15 alkyl, where R3 is different from a n-octyl, n-decyl, n-dodecyl, 2-ethylhexyl and 2-ethyloctyl group when R1 represents a n-butyl group and R2 represents an ethyl group. A method for synthesising the N,N-dialkylamides, and uses of same for extracting uranium and/or plutonium from an aqueous acid solution or for fully or partially separating the uranium from the plutonium contained in an aqueous acid solution and a solution resulting from the dissolution of spent nuclear fuel in nitric acid. A method for treating an aqueous solution resulting from the dissolution of spent nuclear fuel in nitric acid, which allows the uranium and the plutonium contained in the solution to be extracted, separated and decontaminated in a single cycle.

## Claims

### Claim at position 1

1-19. (canceled)

### Claim 20

An N,N-dialkylamide of formula (I):
wherein:
R1 is a linear alkyl group having 1 to 4 carbon atoms;
R2 is a linear alkyl group having 1 to 10 carbon atoms;
R3 is a linear or branched alkyl group having 6 to 15 carbon atoms;
provided that R3 differs from an n-octyl, n-decyl, n-dodecyl, 2-ethylhexyl and 2-ethyloctyl group when R1 is an n-butyl and R2 is an ethyl group.

### Claim 21 (depends on 20)

The N,N-dialkylamide of claim 20, wherein R1 is a methyl, ethyl or n-propyl group.

### Claim 22 (depends on 20)

The N,N-dialkylamide of claim 20, wherein R2 is an n-propyl, n-butyl, n-pentyl, n-hexyl or n-heptyl group.

### Claim 23 (depends on 20)

The N,N-dialkylamide of claim 20, wherein R3 is an n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl or 2-ethyloctyl group.

### Claim 24 (depends on 20)

The N,N-dialkylamide of claim 20, wherein:
R1 is a methyl group, R2 is an n-butyl group and R3 is an n-nonyl group; or
R1 and R2 are each an n-propyl group and R3 is an n-octyl group; or
R1 is an n-propyl group, R2 is an n-pentyl group and R3 is an n-hexyl group.

### Claim 25

A method for synthesizing an N,N-dialkylamide of formula (I):
wherein:
R1 is a linear alkyl group having 1 to 4 carbon atoms;
R2 is a linear alkyl group having 1 to 10 carbon atoms;
R3 is a linear or branched alkyl group having 6 to 15 carbon atoms;
provided that R3 differs from an n-octyl, n-decyl, n-dodecyl, 2-ethylhexyl and 2-ethyloctyl group when R1 is an n-butyl and R2 is an ethyl group;
comprising reacting a carboxylic acid of formula (II):
wherein R1 is a linear alkyl group having 1 to 4 carbon atoms and R2 is a linear alkyl group having 1 to 10 carbon atoms, with an amine of formula HN(CH3)R3 wherein R3 is a linear or branched alkyl group having 6 to 15 carbon atoms, in an organic solvent and with a coupling agent; provided that R3 differs from an n-octyl, n-decyl, n-dodecyl, 2-ethylhexyl or 2-ethyloctyl group when R1 is an n-butyl group and R2 is an ethyl group.

### Claim 26

A method for extracting uranium(VI) and/or plutonium(IV) from an acid aqueous solution, comprising at least one contacting of the aqueous solution with an organic solution comprising a N,N-dialkylamide or a mixture of N,N-dialkylamides of formula (I):
wherein:
R1 is a linear alkyl group having 1 to 4 carbon atoms;
R2 is a linear alkyl group having 1 to 10 carbon atoms;
R3 is a linear or branched alkyl group having 6 to 15 carbon atoms;
provided that R3 differs from an n-octyl, n-decyl, n-dodecyl, 2-ethylhexyl and 2-ethyloctyl group when R1 is an n-butyl and R2 is an ethyl group; in an organic diluent, followed by a separation of the aqueous solution from the organic solution.

### Claim 27 (depends on 26)

The method of claim 26, wherein the organic solution comprises from 1 mol/L to 2 mol/L of the N,N-dialkylamide or mixture of N,N-dialkylamides.

### Claim 28

A method for separating totally or partially uranium(VI) from plutonium(IV) from an acid aqueous solution A1, comprising:
a) a co-extraction of uranium and plutonium from the aqueous solution A1, the co-extraction comprising at least one contacting of the aqueous solution A1 with an organic solution S1 comprising an N,N-dialkylamide or a mixture of N,N-dialkylamides of formula (I):
wherein:
R1 is a linear alkyl group having 1 to 4 carbon atoms;
R2 is a linear alkyl group having 1 to 10 carbon atoms;
R3 is a linear or branched alkyl group having 6 to 15 carbon atoms;
provided that R3 differs from an n-octyl, n-decyl, n-dodecyl, 2-ethylhexyl and 2-ethyloctyl group when R1 is an n-butyl and R2 is an ethyl group; in an organic diluent, followed by a separation of the aqueous solution A1 from the organic solution S1;
b) a stripping of plutonium, in oxidation state +IV, and of a fraction of uranium from the organic solution S1 resulting from a), the stripping comprising at least one contacting of the organic solution S1 with an aqueous solution A2 comprising from 0.1 mol/L to 0.5 mol/L of nitric acid, followed by a separation of the organic solution S1 from the aqueous solution A2; and
c) an extraction of all or part of the uranium fraction contained in the aqueous solution A2 resulting from b), the extraction comprising at least one contacting of the aqueous solution A2 with an organic solution S2 identical to the organic solution S1 of a), followed by a separation of the aqueous solution A2 from the organic solution S2;
whereby there are obtained an aqueous solution comprising plutonium without uranium, or a mixture of plutonium and uranium, and an organic solution comprising uranium without plutonium.

### Claim 29 (depends on 28)

The method of claim 28, wherein the organic solution S1 of a) comprises from 1 mol/L to 2 mol/L of the N,N-dialkylamide or mixture of N,N-dialkylamides.

### Claim 30 (depends on 26)

The method of claim 26 wherein the acid aqueous solution A1 is an aqueous solution resulting from a dissolution of a spent nuclear fuel in nitric acid.

### Claim 31

A single-cycle method for processing an aqueous solution A1 resulting from a dissolution of a spent nuclear fuel in nitric acid, the aqueous solution A1 comprising uranium, plutonium, americium, curium and fission products including technetium, the cycle comprising:
a) a co-extraction of uranium and plutonium from the aqueous solution A1, the co-extraction comprising at least one contacting, in an extractor, of the aqueous solution A1 with an organic solution S1 comprising an N,N-dialkylamide or a mixture of N,N-dialkylamides of formula (I):
wherein:
R1 is a linear alkyl group having 1 to 4 carbon atoms;
R2 is a linear alkyl group having 1 to 10 carbon atoms;
R3 is a linear or branched alkyl group having 6 to 15 carbon atoms;
provided that R3 differs from an n-octyl, n-decyl, n-dodecyl, 2-ethylhexyl and 2-ethyloctyl group when R1 is an n-butyl and R2 is an ethyl group; in an organic diluent, followed by a separation of the aqueous solution A1 from the organic solution S1;
b) a decontamination of the organic solution S1 resulting from a) with respect to americium, curium and fission products, the decontamination comprising at least one contacting, in an extractor, of the organic solution S1 with an aqueous solution A2 comprising from 1 mol/L to 6 mol/L of nitric acid, followed by a separation of the organic solution S1 from the aqueous solution A2;
c) a partitioning of the uranium and plutonium contained in the organic solution S1 resulting from 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:
c1) a stripping of plutonium, in oxidation state +IV, and of a fraction of uranium from the organic solution S1 resulting from b), the stripping comprising at least one contacting, in an extractor, of the organic solution S1 with an aqueous solution A3 comprising from 0.1 mol/L to 0.5 mol/L of nitric acid, followed by a separation of the organic solution S1 from the aqueous solution A3;
c2) an extraction of all or part of the uranium fraction contained in the aqueous solution A3 resulting from c1), the extraction comprising at least one contacting, in an extractor, of the aqueous solution A3 with an organic solution S2 identical to the organic solution S1 of a), followed by a separation of the aqueous solution A3 from the organic solution S2;
d) a decontamination of the organic solution S2 resulting from c1) with respect to technetium, the decontamination comprising:
d1) a stripping of technetium, in oxidation state +IV, from the organic solution S2 resulting from c1), the stripping comprising at least one contacting, in an extractor, of the organic solution S2 with an aqueous solution A4 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 S2 from the aqueous solution A4;
d2) an extraction of the uranium fraction contained in the aqueous solution A4 resulting from d1), the extraction comprising at least one contacting, in an extractor, of the aqueous solution A4 with an organic solution S3 identical to the organic solution S1 of a), followed by a separation of the aqueous solution A4 from the organic solution S3;
e) a stripping of the uranium from the organic solution S3 resulting from d1), the stripping comprising at least one contacting, in an extractor, of the organic solution S3 with an aqueous solution A5 comprising no more than 0.5 mol/L of nitric acid, followed by a separation of the organic solution S3 from the aqueous solution A5; and
f) a regeneration of the organic solution S3 resulting from 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 plutonium without uranium, or a mixture of plutonium and uranium, and the second aqueous solution comprising uranium without plutonium.

### Claim 32 (depends on 31)

The method of claim 31, wherein the organic solution S1 of a) comprises from 1 mol/L to 2 mol/L of the N,N-dialkylamide or mixture of N,N-dialkylamides.

### Claim 33 (depends on 31)

The method of claim 31, wherein the aqueous solution A2 of b) comprises from 4 mol/L to 6 mol/L of nitric acid.

### Claim 34 (depends on 31)

The method of claim 31, wherein b) further comprises a de-acidification of the organic solution S1, the de-acidification comprising at least one contacting of the organic solution S1 with an aqueous solution A6 comprising from 0.1 mol/L to 1 mol/L of nitric acid, followed by a separation of the organic solution S1 from the aqueous solution A6.

### Claim 35 (depends on 31)

The method of claim 31, wherein the contacting of the organic solution S1 and the aqueous solution A3 in the extractor of c1) comprises a circulation of the organic solution S1 and the aqueous solution A3 in the extractor with a ratio of the organic solution S1 flowrate to the aqueous solution A3 flowrate higher than 1.

### Claim 36 (depends on 31)

The method of claim 31, wherein d2) comprises an acidification of the aqueous solution A4 resulting from d1), to bring the concentration of nitric acid in the aqueous solution A4 to a value of at least 2.5 mol/L, the acidification comprising an addition of nitric acid to the extractor of d2).

### Claim 37 (depends on 31)

The method of claim 31, wherein the contacting of the organic solution S3 and the aqueous solution A5 in the extractor of e) comprises a circulation of the organic solution S3 and the aqueous solution A5 in the extractor with a ratio of the organic solution S3 flowrate to the aqueous solution A5 flowrate higher than 1.

### Claim 38 (depends on 28)

The method of claim 28, wherein the aqueous solution A1 is an aqueous solution resulting from a dissolution of a spent nuclear fuel in nitric acid.