Mesoporous organic material, useful in particular for extracting uranium(VI) from aqueous media including phosphoric acid, and uses thereof

Abstract

A mesoporous organic material which makes it possible to extract, using the liquid-solid extraction technique, the uranium(VI) contained in an aqueous medium including phosphoric acid, with high efficiency and high selectivity for the iron that the medium can likewise contain. The material is likely to be obtained by cross-linking polymerisation of a monomer of formula (I) below, wherein: R.sup.1, R.sup.2 and R.sup.3 are, independently from one another, H, a C.sub.1 to C.sub.12 saturated or unsaturated, linear or branched hydrocarbon group, or a polymerisable group, with the condition that at least one of R.sup.1, R.sup.2 and R.sup.3 is a polymerisable group; R.sup.4 and R.sup.5 are, independently from one another, H or a C.sub.1 to C.sub.8 saturated or unsaturated, linear or branched hydrocarbon group; the cross-linking polymerisation being carried out in the presence of a cross-linking agent and one or more pore-forming agents.

Claims

1. A mesoporous organic material obtainable by a cross-linking polymerisation of a monomer of formula (I): ##STR00007## in which: R.sup.1, R.sup.2 and R.sup.3 represent, independently of each other, a hydrogen atom, a saturated or unsaturated, linear or branched hydrocarbon group comprising 1 to 12 carbon atoms or a polymerisable group comprising at least one unsaturation, provided that at least one of R′, R.sup.2 and R.sup.3 is a polymerisable group comprising at least one unsaturation; R.sup.4 and R.sup.5 represent, independently of each other, a hydrogen atom or a saturated or unsaturated, linear or branched hydrocarbon group comprising 1 to 8 carbon atoms; the cross-linking polymerisation being made with a cross-linking agent and one or several blowing agents.

2. The material of claim 1, in which the unsaturation of the polymerisable group is an ethylene unsaturation.

3. The material of claim 2, in which the polymerisable group has formulas (a), (b), (c), (d), (e), (f) or (g):
—(CH.sub.2).sub.q—X  (a)
—(CH.sub.2).sub.p—C(O)—O—(CH.sub.2).sub.q—X  (b)
—(CH.sub.2).sub.p—O—C(O)—(CH.sub.2).sub.q—X  (c)
—(CH.sub.2).sub.p—O—C(O)—NH—(CH.sub.2).sub.q—X  (d)
—(CH.sub.2).sub.p—O—(CH.sub.2).sub.q—X  (e)
—(CH.sub.2).sub.p—O—C.sub.2H.sub.5—(O—C.sub.2H.sub.5).sub.q—X  (f)
—(CH.sub.2).sub.p-triazole-(CH.sub.2).sub.q—X  (g) in which: p is an integer from 1 to 6; q is an integer from 0 to 12; and X represents a group of formula (i) or (ii): ##STR00008## in which: R.sup.a, R.sup.b and R.sup.c represent, independently of each other, a hydrogen atom or a linear or branched alkyl group comprising 1 to 10 carbon atoms; and ##STR00009## represents a covalent bond by which X is bonded to the rest of the group of formula (a), (b), (c), (d), (e), (f) or (g).

4. The material of claim 3, in which X represents a group of formula (II) in which R.sup.a, R.sup.b and R.sup.c all three represent a hydrogen atom.

5. The material of claim 4, in which the polymerisable group has formula (a) in which q is from 1 to 4.

6. The material of claim 1, in which: R.sup.1 and R.sup.2 represent, independently of each other, a hydrogen atom, a saturated or unsaturated, linear or branched hydrocarbon group comprising 1 to 12 carbon atoms; and R.sup.3 represents a polymerisable group.

7. The material of claim 6, in which: R.sup.1 and R.sup.2 are identical to each other and represent a linear or branched alkyl group comprising 1 to 12 carbon atoms; and R.sup.4 and R.sup.5 represent, independently of each other, a hydrogen atom or a linear or branched alkyl group comprising 1 to 8 carbon atoms.

8. The material of claim 1, in which the cross-linking agent is a polyvinyl derivative of benzene or of naphthalene.

9. The material of claim 1, in which the cross-linking polymerisation of the monomer is made with a first blowing agent that is an organic solvent in which the monomer and the cross-linking agent are soluble, and a second blowing agent which is a polymer.

10. The material of claim 9, in which the first blowing agent is toluene and the second blowing agent is polyethylene glycol.

11. The material of claim 1, in which the cross-linking polymerisation is an emulsion polymerisation.

12. A method for recovering uranium(VI) from an aqueous medium comprising phosphoric acid and uranium(VI), comprising: an extraction of uranium(VI) from the aqueous medium by a mesoporous organic material obtainable by a cross-linking polymerisation of a monomer of formula (I): ##STR00010## in which: R.sup.1, R.sup.2 and R.sup.3 represent, independently of each other, a hydrogen atom, a saturated or unsaturated, linear or branched hydrocarbon group comprising 1 to 12 carbon atoms or a polymerisable group comprising at least one unsaturation, provided that at least one of R.sup.1, R.sup.2 and R.sup.3 is a polymerisable group comprising at least one unsaturation; R.sup.4 and R.sup.5 represent, independently of each other, a hydrogen atom or a saturated or unsaturated, linear or branched hydrocarbon group comprising 1 to 8 carbon atoms; the cross-linking polymerisation being made with a cross-linking agent and one or several blowing agents; the extraction comprising contacting the aqueous medium with the material, and then separating the aqueous medium from the material; and a stripping of uranium(VI) from the material obtained at the end of the extraction, the stripping comprising contacting the material with an acid or basic aqueous solution, and then separating the material from the acid or basic aqueous solution.

13. The method of claim 12, in which the aqueous medium comprises 0.01 mol/L to 9 mol/L of phosphoric acid.

14. The method of claim 12, in which the aqueous medium further comprises iron.

15. The method of claim 12, in which the aqueous medium results from an attack of a phosphate ore by sulphuric acid.

16. A method for extracting uranium(VI) from an aqueous medium comprising phosphoric acid and uranium(VI), comprising: contacting the aqueous medium with a mesoporous organic material obtainable by a cross-linking polymerisation of a monomer of formula (I): ##STR00011## in which: R.sup.1, R.sup.2 and R.sup.3 represent, independently of each other, a hydrogen atom, a saturated or unsaturated, linear or branched hydrocarbon group comprising 1 to 12 carbon atoms or a polymerisable group comprising at least one unsaturation, provided that at least one of R.sup.1, R.sup.2 and R.sup.3 is a polymerisable group comprising at least one unsaturation; R.sup.4 and R.sup.5 represent, independently of each other, a hydrogen atom or a saturated or unsaturated, linear or branched hydrocarbon group comprising 1 to 8 carbon atoms; the cross-linking polymerisation being made with a cross-linking agent and one or several blowing agents; and then separating the aqueous medium from the material.

17. The method of claim 16, in which the aqueous medium comprises 0.01 mol/L to 9 mol/L of phosphoric acid.

18. The method of claim 16, in which the aqueous medium further comprises iron.

19. The method of claim 16, in which the aqueous medium results from an attack of a phosphate ore by sulphuric acid.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows a curve illustrating the volume distribution of pore diameters (semi-logarithmic dV/d log(D) function, expressed in cm.sup.3/g.Math.Å, as a function of the pore diameter, noted D and expressed in Å), as determined by adsorption-desorption of nitrogen by applying the Barrett-Joyner-Halenda method (BJH method), for a first material of the invention.

(2) FIG. 2 shows a curve illustrating the volume distribution of pore diameters (semi-logarithmic dV/d log(D) function, expressed in cm.sup.3/g.Math.Å, as a function of the pore diameter, noted D and expressed in Å), as determined by adsorption-desorption of nitrogen by applying the BJH method, for a second material of the invention.

(3) FIG. 3 shows a curve illustrating the volume distribution of pore diameters (semi-logarithmic dV/d log(D) function, expressed in cm.sup.3/g.Math.Å, as a function of the pore diameter, noted D and expressed in Å), as determined by adsorption-desorption of nitrogen by applying the BJH method, for a material with the same chemical composition as the materials for which FIGS. 1 and 2 are applicable, but that is different in that it is microporous.

DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS

Example 1: Preparation of Materials of the Invention

(4) Material M1:

(5) A first material of the invention, referred to as material M1 hereinafter, is prepared by cross-linking polymerisation of the amidophosphonate of formula below:

(6) ##STR00006##
and divinylbenzene (or DVB).

(7) This polymerisation is made in suspension, that is to say by a method using two phases immiscible with each other, namely: a dispersed phase—or organic phase—comprising monomers (i.e. the amidophosphonate and DVB), azobisisobutyronitrile (or AIBN) as a primer, and polypropylene glycol (or PPG) as a polymer blowing agent, in solution in toluene, the toluene acting as both solvent and blowing agent; and a dispersing phase—or aqueous phase—comprising polyvinyl alcohol (or PVA) as an emulsifying agent, and sodium chloride as a dispersing agent, in solution in water.

(8) To achieve this, the first step is to prepare the dispersing phase that has the composition presented in Table I below.

(9) TABLE-US-00001 TABLE I Component Quantity by mass (g) Water 154.5 NaCl 5.1 (i.e. a NaCl/water mass ratio of 3.30%) PVA 1.16 (Sigma-Aldrich, ref.: 363073) (i.e. a PVA/water mass ratio of 0.75%)

(10) This dispersing phase is then placed in a 2-neck flask that is kept stirred (using a 5 cm half-moon stirring paddle) while scavenging the flask with argon to eliminate all traces of oxygen from said dispersing phase.

(11) The next step is to prepare the dispersed phase that has the composition presented in Table II below.

(12) TABLE-US-00002 TABLE II Component Quantity by mass (g) Toluene 3.113 Amidophosphonate 2.32  (i.e. an amidophosphonate/monomer mass ratio of 89.4%) DVB (degree of purity: 0.343 80%) (Sigma-Aldrich, (i.e. a DVB/monomer mass ratio of 10.6%) ref.: 414565) AlBN 0.028 (Molekula) (i.e. an AlBN/monomer molar ratio of 2%) PPG 0.130 (BASF, Pluriol ™ P900) (i.e. a PPG/toluene mass ratio of 4%)

(13) The dispersed phase is added to the dispersing phase and the whole is kept stirred and under argon scavenging for 1 hour to obtain a homogeneous emulsion.

(14) Argon scavenging is stopped. The temperature of the emulsion is brought to 80° C. and the emulsion is kept at this temperature for 5 hours to make the cross-linking polymerisation that results in the formation of balls in the reaction medium.

(15) The balls thus formed are recovered by filtration, washed with water, ethanol and acetone successively, and are then subjected to a Soxhlet extraction for 24 hours with acetone to eliminate all traces of polymer blowing agent and solvent. They are then dried in a drying oven heated to 90° C. for 24 hours.

(16) These balls are composed of a material with the following physicochemical characteristics: average pore diameter (as determined by adsorption-desorption of nitrogen, using the BJH method): 20-40 nm (see FIG. 1); specific surface area (as determined by adsorption-desorption of nitrogen using the Brunauer-Emmett-Teller method (BET method): 49 m.sup.2/g; molar quantity of amidophosphonate molecules in the material (as determined by an NMR analysis of phosphorus): 1.6 mmol/g of material.

(17) Material M2:

(18) A second material of the invention, referred to as material M2 hereinafter, is prepared using the same protocol as that described above for preparing material M1 except that the dispersing phase which is used has the composition presented in Table III below.

(19) TABLE-US-00003 TABLE III Component Quantity by mass (g) Water 148.30  NaCl 4.89 (i.e. a NaCl/water mass ratio of 3.30%) PVA 1.11 (Sigma-Aldrich, ref.: 363073) (i.e. a PVA/water mass ratio of 0.75%)

(20) Material M2 has the following physicochemical characteristics: average pore diameter (as determined by adsorption-desorption of nitrogen, using the BJH method): 25-30 nm (see FIG. 2); specific surface area (as determined by adsorption-desorption of nitrogen using the BET method: 29 m.sup.2/g; molar quantity of amidophosphonate molecules in the material (as determined by an NMR analysis of phosphorus): 1.9 mmol/g of material.

Example 2: Properties of Materials of the Invention

(21) 2.1—Extraction of Uranium(VI) from Aqueous Solutions of Phosphoric Acid with a Variable Content of Uranium(VI):

(22) Extraction properties of material M1 were firstly evaluated using an extraction isotherm at 25° C., the objective of which is to determine the quantity of uranium(VI) that is extracted, at equilibrium, from an aqueous solution of phosphoric acid by this material as a function of the concentration of uranium(VI) in this solution initially.

(23) To achieve this, 50 mg samples of material M1 are contacted (by immersion) with 50 mL of a series of aqueous solutions each comprising 5 mol/L of phosphoric acid and 0.01 g/L to 10 g/L of uranium(VI). The dispersions thus obtained are stirred vigorously for 24 hours in a stirrer-incubator to keep them at a constant temperature of 25° C. The samples of material M1 are then recovered by filtration of the dispersions.

(24) Quantities of uranium(VI) present in the filtrates are measured. When these measurements cannot be made because the quantities of uranium(VI) present in the filtrates are too small, the measurements are made on aqueous solutions resulting from the wet mineralisation of samples of material M1, i.e. the dissolution of these samples in nitric acid at 8-10 mol/L under microwaves.

(25) In all cases, the measurements are made by inductively coupled plasma atomic emission spectroscopy (ICP-AES).

(26) For each aqueous solution of phosphoric acid used in the tests, the uranium(VI) extraction capacity of material M1, denoted Q.sub.U and expressed in mg of U(VI)/g of material, is determined: either by the following formula:

(27) $Q_U=\left({\left[U\right]}_i-{\left[U\right]}_f\right)\times \frac{V}{m}$
in which: [U].sub.i: initial concentration of uranium(VI) in the aqueous solution of phosphoric acid (in mg/L); [U].sub.f: final concentration of uranium(VI) in the filtrate (in mg/L); V: volume of the aliquot of the aqueous solution of phosphoric acid in which the material was immersed (in L); and m: mass of the sample of material M1 that was immersed in the aqueous solution of phosphoric acid (in mg); or by the ratio of the quantity of uranium(VI), as measured by ICP-AES in the aqueous solution of nitric acid derived from the mineralisation of the sample of material M1, to the mass of the sample of material M1 that had been immersed in the aqueous solution of phosphoric acid.

(28) The results obtained are given in Table IV below.

(29) TABLE-US-00004 TABLE IV [U].sub.i Q.sub.U (g/L) (mg/g) 0.01 6 0.03 14 0.05 20 0.10 37 0.15 41 0.20 45 0.30 55 0.50 62 1 67 5 92 9 103 47 118 64 112

(30) This table shows that the extraction capacity of material M1 at saturation is equal to 112 mg U(VI)/g of material, which demonstrates that material M1 has an extraction capacity a very much higher than the extraction capacity of materials proposed in the state of the art for extracting uranium(VI) from a medium comprising 5 mol/L of phosphoric acid.

(31) 2.2—Extraction of Uranium(VI) from Aqueous Solutions of Phosphoric Acid Comprising Uranium(VI) and Iron:

(32) Extraction properties of material M1 are also evaluated by a series of extraction tests made using three different synthetic aqueous solutions, referred to as S1, S2 and S3 hereinafter, that have uranium(VI) and iron contents representative of aqueous solutions of phosphoric acid actually used in the fabrication of phosphate fertilisers, but for which the concentration of phosphoric acid is varied from 1 mol/L to 9 mol/L.

(33) The composition of solutions S1, S2 and S3 is given in Table V below.

(34) TABLE-US-00005 TABLE V Aqueous [H.sub.3PO.sub.4] [U(VI)] [Fe] solution (mol/L) (mg/L) (mg/L) S1 1 192 1831 S2 5 189 1795 S3 9 186 1796

(35) For each solution 51, S2 and S3, extractions are made until material M1 is saturated with uranium(VI).

(36) To that end, 50 mg samples of material M1 are contacted (by immersion) with a 50 mL first aliquot of each of solutions S1, S2 and S3, and then the dispersions obtained are vigorously stirred for 24 hours in a stirrer-incubator to keep them at a constant temperature of 25° C.

(37) Samples of material M1 are then recovered by filtration of the dispersions and are put back into contact (by immersion) for 24 hours, under the same stirring and temperature conditions as before, with a new aliquot of 50 mL of the same solution as before and this protocol is repeated as many times as necessary until the samples of material M1 are saturated with uranium(VI).

(38) Saturation of the samples of material M1 with uranium(VI) is checked by a systematic ICP-AES analysis of uranium(VI) present in the filtrates. A sample of material M1 is deemed to be saturated with uranium(VI) when the filtrate obtained after contacting this sample with an aliquot of aqueous solution has the same content of uranium(VI) as this aliquot.

(39) The uranium(VI) extraction capacity of material M1, denoted Q.sub.U and expressed in mg of U(VI)/g of material, is determined using the same formula as that indicated in item 2.1 above.

(40) The enrichment factor of material M1 with uranium(VI) and iron, denoted F.Math.E.sub.Fe.sup.U, is determined from quantities of uranium(VI) and iron measured by ICP-AES in aqueous solutions resulting from the wet mineralisation of samples of this material, using the following formula:

(41) $F.E_{\mathrm{Fe}}^U=\frac{Q_U/Q_{\mathrm{Fe}}}{{\left[U\right]}_i/{\left[\mathrm{Fe}\right]}_i}$
in which:
Q.sub.U: concentration of uranium(VI) in the material at saturation (in mmol/g);
C.sub.Fe: concentration of iron in the material at saturation (in mmol/g);
[U].sub.i: initial concentration of uranium(VI) in the aqueous solution of phosphoric acid (in mmol/L);
[Fe].sub.i: initial concentration of iron in the aqueous solution of phosphoric acid (in mmol/L).

(42) This enrichment factor provides information about the selectivity of material M1 for uranium(VI) with regard to iron: thus, an enrichment factor of more than 1 indicates selectivity for uranium(VI) with regard to iron, and this selectivity is higher when the enrichment factor is higher.

(43) The results obtained are given in Table VI below.

(44) TABLE-US-00006 TABLE VI Aqueous Q.sub.U solution (mg/g) F.E.sub.Fe.sup.U S1 51 44 S2 42 37 S3 24 31

(45) This table shows that the uranium(VI) extraction capacity and the enrichment factor of material M1 reduce when the concentration of phosphoric acid in the aqueous solution from which uranium(VI) is extracted increases, but nevertheless remain very high for a concentration of phosphoric acid greater than or equal to 5 mol/L.

(46) 2.3—Stripping of Uranium(VI) from Materials of the Invention:

(47) The reversibility of material M1, that is to say the possibility of recovering in aqueous solution the uranium(VI) which has been extracted by this material, is evaluated by a stripping test (or elution test) that is made on a sample of material M1 that has previously been loaded with uranium(VI) and iron by three successive contacts (with vigorous stirring for 24 hours and at 25° C.) with aliquots (50 mL) of solution S2 as defined in point 2.2 above.

(48) The uranium(VI) content of this sample is 26.4 mg/g, while its iron content is 7.20 mg/g.

(49) The stripping test consists of contacting (by immersion) the sample of material M1 comprising uranium(VI) and iron with 5 mL of a solution comprising 1 mol/L of ammonium carbonate ((NH.sub.4).sub.2CO.sub.3), vigorously stirring the dispersion thus obtained for 24 hours in a stirrer-incubator capable of keeping the temperature constant at 25° C., and then recovering the sample of material M1 by filtration.

(50) Quantities of uranium(VI) and iron present in the filtrate are measured by ICP-AES.

(51) The results obtained are given in Table VII.

(52) TABLE-US-00007 TABLE VII U Fe Quantity present on the sample of material M1 1.32 0.36 before stripping (in mg) Quantity recovered in the filtrate after 1.30 0.31 stripping (in mg) Recovery ratio (in %) >95 >86

(53) This table shows that uranium(VI) and iron can be quantitatively stripped from the material of the invention simply by contacting this material with a solution of ammonium carbonate at 1 mol/L. Therefore, for the material of the invention, iron is not a “poison” that could limit performances during extraction/stripping cycles.

(54) 2.4—Ability of the Materials of the Invention to Achieve Several Extraction/Stripping Cycles:

(55) In order to check if material M1 is capable of retaining its extraction properties after an extraction/stripping cycle, a 50 mg sample of this material is submitted to: two successive extraction cycles each comprising three contacts (with vigorous stirring for 24 hours and at 25° C.) of the sample of material M1 with aliquots (50 mL) of an aqueous solution of phosphoric acid, hereinafter referred to as S4, that comprises 5 mol/L of phosphoric acid, 192 mg/L of uranium(VI) and 1797 mg/L of iron, with between the two extraction cycles, a stripping (or elution) of uranium(VI) and iron that were extracted from the sample of material M1 during the first extraction cycle, this stripping being made by contacting (with vigorous stirring for 24 hours and at 25° C.) a sample of material M1 with 5 mL of an aqueous solution comprising 1 mol/L of ammonium carbonate.

(56) Quantities of uranium(VI) present in the filtrates obtained at the end of the different contacts are measured by ICP-AES and quantities of uranium(VI) extracted during these contacts are calculated by taking the difference between the quantity of uranium(VI) initially present in the aliquots of solution S4 and the quantities of uranium(VI) thus measured.

(57) For each contact made, the uranium(VI) extraction capacity of material M1, denoted Q.sub.U and expressed in mg of U(VI)/g of material, is determined using the same formula as that indicated in item 2.1 above.

(58) The results obtained are given in Table VIII.

(59) TABLE-US-00008 TABLE VIII 1.sup.st contact 2.sup.nd contact 3.sup.rd contact Q.sub.U 1.sup.st extraction cycle 3.9 11.5 16.7 (mg/g) 2.sup.nd extraction cycle 10.3 15.4 18.4

(60) This table shows that during the second extraction cycle, the material of the invention has an ability to extract uranium(VI) which is comparable to its ability during the first extraction cycle.

(61) Therefore, due to its physical and chemical structure, the material of the invention is perfectly resistant to acid and basic solutions such as those used in the first extraction cycle and for the stripping.

(62) 2.5—Influence of the Physical Structure of Materials of the Invention on their Extracting Properties

(63) Extraction tests are carried out to compare extraction properties of materials M1 and M2 with the extraction properties of a material, denoted material M3 hereinafter, that has the same chemical composition as materials M1 and M2 but that is microporous (in accordance with the definition of the IUPAC—see FIG. 3) instead of being mesoporous.

(64) Material M3 is obtained using the same operating protocol as that described in example 1 above but using a dispersed phase in which the blowing co-agent, i.e. PPG, is replaced by toluene. Therefore, this dispersed phase has the following composition: toluene: 3.243 g; amidophosphonate: 2.32 g; DVB: 0.343 g; AIBN: 0.028 g.

(65) Extraction tests are performed using two different aqueous solutions of phosphoric acid, namely solution S4 used in example 2.4 above (H.sub.2PO.sub.4: 5 mol/L; U(VI): 192 mg/L; Fe: 1797 mg/L) and a solution hereinafter called S5, that comprises 5 mol/L of phosphoric acid, 171 mg/L of uranium(VI) and 1875 mg/L of iron, until saturation of materials M1, M2 and M3.

(66) To that end, a 50.3 mg sample of material M1 and a 51.6 mg sample of material M2 are each contacted (by immersion) with a 50 mL aliquot of solution S4, while a sample of 250 mg of material M3 is contacted (by immersion) with a 10 mL aliquot of solution S5, and then the dispersions obtained are vigorously stirred for 24 hours in a stirrer-incubator to keep them at a constant temperature of 25° C.

(67) Samples of materials M1, M2 and M3 are recovered by filtration and are put back into contact (by immersion) for 24 hours, under the same stirring and temperature conditions as before, with a new aliquot of the same solution as before, and this protocol is repeated as many times as necessary until the samples of materials M1, M2 and M3 are saturated with uranium(VI).

(68) Saturation of the samples of materials M1, M2 and M3 with uranium(VI) is demonstrated by a systematic ICP-AES analysis of uranium(VI) present in the filtrates. As before, a sample of a material is deemed to be saturated with uranium(VI) when the filtrate obtained after contacting this material with an aliquot of aqueous solution has the same content of uranium(VI) as this aliquot.

(69) The uranium(VI) extraction capacity of materials, denoted Q.sub.U and expressed in mg of U(VI)/g of material, is determined using the same formula as that indicated in item 2.1 above.

(70) The enrichment factor of materials M1, M2 and M3 with uranium(VI) and iron, denoted F.Math.E.sub.Fe.sup.U, is determined from quantities of uranium(VI) and iron measured by ICP-AES in aqueous solutions resulting from the wet mineralisation of samples of these materials, using the same formula as that indicated in item 2.2 above.

(71) Table IX below indicates the aqueous solution used, the volume of the aliquot of this aqueous solution (V.sub.solution), the mass of the sample of tested material, (M.sub.sample) and the values of Q.sub.U and F.Math.E.sub.Fe.sup.U obtained, for each of materials M1, M2 and M3.

(72) TABLE-US-00009 TABLE IX V.sub.solution M.sub.sample Q.sub.U Material Aqueous solution (mL) (mg) (mg/g) M1 S4 50 50.3 58 M2 S4 50 51.6 56 M3 S5 10 250 5

(73) This table demonstrates the benefit provided by the mesoporosity of the materials of the invention because their extraction power is more than 10 times higher than that of a material with the same chemical composition but with a microporosity.

(74) 2.6—Comparison of the Extraction Properties of Materials of the Invention with Those of Materials of the State of the Art:

(75) Comparison with Commercial Ion-Exchange Resins:

(76) Extraction tests were made to compare the extraction properties of material M1 with those of chelating ion-exchange resins that are marketed under the names Amberlite™ IRC 747 (Dow), Lewatit™ TP 260 (Lanxess), Diphonix™ (Triskem International) and Monophos™ (DSM).

(77) These extraction tests are made until the material M1 and the commercial resins are saturated, proceeding as described above.

(78) Table X below indicates the composition of the aqueous solution used, the volume of the aliquot of this aqueous solution (V.sub.solution), the mass of the sample of tested material (M.sub.sample) as well as the values of Q.sub.U and F.Math.E.sub.Fe.sup.U obtained, for each of the five tested materials.

(79) TABLE-US-00010 TABLE X Aqueous solution [H.sub.3PO.sub.4] [U] [Fe] V.sub.solution M.sub.sample Q.sub.U Material (mol/L) (mg/L) (mg/L) (mL) (mg) (mg/g) F.E.sub.Fe.sup.U M1 5 192 1797 50 50.3 58 37 Amberlite ™ IRC 5 178 1833 5 52.7 4 1.3 747 Lewatit ™ TP 260 5 192 1797 5 50.7 9 2 Diphonix ™ 5 191 1993 5 50.9 2 1.5 Monophos ™ 5 191 1993 5 51.4 1 1.5

(80) This table shows that the material M1 has considerably higher performances in terms of uranium(VI) extraction capacity and selectivity for uranium(VI) regarding iron than commercially available ion-exchange resins.

(81) Comparison with a Material According to Reference [1]:

(82) Extraction tests are also performed to compare the extraction properties of material M1 with those of a material that comprises an SBA-15 type mesoporous silica, functionalised by post-grafting of a plurality of molecules complying with formula (I) in which each of R.sup.1 and R.sup.2 represents a 2-ethylhexyl group, R.sup.3 represents a —CH.sub.2—COOH group, R.sup.4 represents an ethyl group while R.sup.5 represents a hydrogen atom.

(83) Preparation of this material is described in reference [1].

(84) Extraction tests are made until the two materials are saturated, proceeding as described above.

(85) Table XI below indicates the composition of the aqueous solution used, the volume of the aliquot of this aqueous solution (V.sub.solution), the mass of the sample of the tested material (M.sub.sample) as well as the values of Q.sub.U obtained, for each of the two tested materials.

(86) TABLE-US-00011 TABLE XI Aqueous solution tested [H.sub.3PO.sub.4] [U] [Fe] V.sub.solution M.sub.sample Q.sub.U Material (mol/L) (mg/L) (mg/L) (mL) (mg) (mg/g) M1 5 200 2000 50 49.9 51.6 Material of 5 200 2000 50 50.1 0.5 reference [1]

(87) This table shows that the material of the invention has a uranium(VI) extraction capacity that is a hundred times higher than that of a material obtained by post-grafting of an amidophosphonate compound on an inorganic support.

REFERENCES

(88) [1] International application PCT WO 2014/127860 [2] Yamabe et al., Separation Science and Technology 2001, 36(15), 3511-3528 [3] Jyo et al, Journal of Applied Polymer Science 1997, 63, 1327-1334 [4] Barrett, Joyner and Halenda, Journal of the American Chemical Society 1951, 73(1), 373-380