Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J45/00—Ion-exchange in which a complex or a chelate is formed; Use of material as complex or chelate forming ion-exchangers; Treatment of material for improving the complex or chelate forming ion-exchange properties

Definitions

• the present invention relates to inorganic-organic hybrid gels for the extraction of chemical species from aqueous solutions.
• document US-A-4, 203, 952 (1) describes a process for removing heavy metals and transition metals other than platinum, from a solution, by bringing the solution into contact with an inorganic solid phase comprising on the surface hydroxyl groups to which a silicon compound comprising reactive functions of the thiol or amine type having an affinity for the metal to be extracted is grafted.
• Y is an alkoxy group or a halogen atom capable of reacting with the hydroxyl groups of the substrate and X represents a nitrogen-containing thiol, amino or heterocyclic group.
• the technique described in this document therefore leads to a grafting of the extracting entity on the surface of the substrate which can be silica or silica gel, but there is no fixation of the extracting entity in the internal structure of the substrate.
• CMPO octyl (phenyl) -N, N '- diisobutyl carbamoylmethyl phosphine
• the extractant is not fixed by a covalent bond to the substrate, and it is not integrated by chemical bonds in the structure of the latter.
• the subject of the present invention is specifically hybrid inorganic-organic gels in which the extracting entity is integrated into the structure of the gel during its manufacture.
• the organic-inorganic hybrid gel for the extraction of at least one chemical species from an aqueous solution comprises a network of inorganic units of formula:
• M represents Si, Ti, Zr or Al, into which are integrated organic molecules complexing the species (s) to be extracted, each organic molecule being covalently linked to one or more M atoms of the network.
• the organic molecules comprise at least one functional group having complexing properties with respect to the species to be extracted.
• this functional group can be chosen from amino, ether, hydroxy, amido, pyridino and bipyridino groups, or any group organic having an electron donor atom of type (0, N, S).
• the inorganic units can be of the silica gel, titanium oxide gel, zirconium oxide gel or alumina gel type.
• the hybrid gel is based on silica, the inorganic units of the network being units:
• all the atoms of the network are linked to a complexing organic molecule.
• a gel of this type is particularly interesting because it comprises a very high density of complexing molecules having an affinity for the chemical species or species to be extracted.
• only part of the M atoms of the network is covalently linked to a complexing organic molecule.
• at least 9% of the M atoms in the network are linked to complexing molecules.
• the invention also relates to a process for preparing a hybrid organic-inorganic gel as defined above, from silicon alkoxides functionalized with organic groups and optionally silicon alkoxides.
• the sol-gel technique is used, and polymerization by polycondensation, in the presence of water, at least one functionalized metal alkoxide of formula:
• M represents Si, Ti, Zr or Al
• - L represents an organic group comprising at least one complexing organic function
• R 1 represents an organic group, preferably an alkyl group
• the functionalized metal alkoxide corresponding to formula (I) or (II) described above is polymerized with a metal alkoxide of formula:
• M represents Si, Ti, Zr or Al
• R 2 is an organic group, preferably alkyl
• the alkyl groups used for R 1 and R 2 have from 1 to 12 carbon atoms.
• Methyl and ethyl groups can be used, in particular.
• the complexing organic function or functions present in the organic group L can be in particular amino, ether, hydroxy, amido, pyridino or bipyridino groups.
• Such L groups can respond, for example, to the following formulas:
• R signifies an organic group, preferably alkyl, having for example from 1 to 12 carbon atoms, such as methyl and ethyl groups.
• the formation of the gel corresponds to the following schemes:
• M, R 1 , R 2 , £ and m are as defined above, n is an integer ranging from 1 to 1000 and y and z are numbers ranging from 1 to 4.
• the resulting material is a hybrid gel of the metal oxide M in which are integrated by covalent bond, during the formation of the solid phase of the gel, organic molecules L having extracting properties.
• This manufacturing method differs from conventional grafting processes in that the mineral support, that is to say the gel, is constructed at the same time as the organic pattern is integrated into the material. We can thus precisely control the stoichiometry and the molecular structure of the solid. Thus, by appropriately choosing the organic group L and the mineral skeleton, it is possible to vary certain properties of the gel obtained, such as the selectivity with respect to the chemical species to be extracted, such as actinides, and the three-dimensional molecular structure of the material.
• the formulas given above for the gels of the invention and their preparation correspond to a fully condensed three-dimensional network.
• the gels obtained correspond to a degree of condensation of 70 to 90% for which there remain a few non-condensed OH or OR groups.
• LSiO ⁇ , 5 becomes, in this case, LSiO x (OH) y (OR) z with 1 ⁇ x ⁇ 1.5 and 0 ⁇ y + z ⁇ 0.5.
• organic groups of this type mention may be made of aromatic or aliphatic groups, such as those corresponding to the following formulas:
• the metal alkoxide (s) is generally dissolved in a suitable solvent such as ethanol, then water and a nucleophilic catalyst such as fluoride are added. ammonium, it is also possible to use basic or acid catalysts.
• the amounts of solvent are generally such that they correspond to 0.5 to 1 ml of ethanol per mmol of silicon and the quantity of water added must correspond to at least 0.5 equivalent of water per alkoxy group OR 1 and optionally OR 2 and OR 3 present in the metal alkoxides used.
• the amount of catalyst is generally 0.1% relative to the silicon.
• the reaction can be carried out at room temperature, with stirring, then allowing the reaction medium to stand until it gels and then allowing it to age for, for example, a week.
• the preparation of the gel in the presence of the chemical species to be extracted in order to include this species in the gel during its manufacture, then subject the gel to washing in order to to eliminate this species.
• This procedure makes it possible, by an imprint effect on the molecular structure or on the texture (porosity, specific surface) of the gel (template effect), to improve its selectivity with respect to the species to be extracted.
• This species can in particular be a metal ion.
• a subject of the invention is also the functionalized silicon alkoxides used for the preparation of hybrid silica gels, these alkoxides correspond to the following formulas:
• the gels obtained by the process of the invention can be recovered in granular form or in the form of a thin layer.
• the ions to be extracted can be ions of actinides and / or lanthanides.
• the extraction process corresponds to extraction chromatography and it can be carried out in a column filled with the granular gel.
• the extraction can be carried out by a membrane separation technique by circulating on one side of the membrane the aqueous solution containing the ions to be extracted and on the other side of the membrane, an aqueous re-extraction solution.
• Figure 1 is a graph illustrating the results obtained for extracting americium from an aqueous solution using a hybrid gel according to the invention. This figure illustrates the evolution of the partition coefficient Kd of americium as a function of the acidity of the aqueous solution containing americium.
• FIG. 2 illustrates the results obtained for the extraction of plutonium with the gel of FIG. I and represents the variations of Kd as a function of the acidity of the aqueous solution.
• FIG. 3 illustrates the results obtained during the extraction of americium, plutonium and neodymium using another gel in accordance with the invention; it represents the evolution of Kd as a function of the acidity of the aqueous solution.
• FIG. 4 illustrates the results obtained for the extraction of americium by means of another gel in accordance with the invention, it represents the evolution of Kd as a function of the concentration of nitric acid (in mole / 1).
• Table 1 illustrates the functionalized alkoxysilanes used in Examples 6 to 25 for the preparation of hybrid gels according to the invention.
• Examples 1 to 5 illustrate the synthesis of the functionalized alkoxysilanes (compounds 3 to 7 of Table 1).
• the infrared IR spectra were recorded on a PERKIN-ELMER 1000 spectrometer with Fourier transform, the NMR ⁇ ti and 13 C on BRUKER AC 200 and 29 Si on BRUKER AC 250.
• the mass spectra MS were obtained on the apparatus JEOL JMS-DX 300.
• Procedure A 500 ml three-necked flask fitted with a mechanical stirrer and a dropping funnel is used. It contains 250 ml of ether, 3.42 g (0.074 mole) of ethanol and 7.5 g of triethylamine (0.074 mole). The whole is cooled to 0 ° C. 5.72 g (0.024 mole) of 4- [2-- trichlorosilyl) ethylpyridine] (Gelest, 25% in the toluene) are introduced dropwise. The temperature is then allowed to return to ambient and the stirring is maintained for 12 hours.
• reaction medium is then filtered and evaporated on a rotary evaporator.
• One uses a three-necked flask of 11 equipped with a mechanical stirring and a bulb with bromine. It contains 13.94 g of 2- [2- (trichlorosilyl) ethyl] pyridine (0.058 mole, Gelest) suspended in 450 ml of ether and 40 ml of triethylamine (0.27 mole). The whole is cooled to 0 ° C. 12.32 g of ethanol (0.27 mol) diluted in 40 ml of ether are added dropwise. At the end of the addition, the temperature is allowed to return to ambient and the stirring is maintained for 12 h. The product is isolated by distillation (7.46 g, R 48%).
• the purification of the product could not be carried out: it degrades indeed during its distillation or its passage over a silica column, even protected. However, very few impurities could be detected by NMR; The deviation observed during the analysis from the theoretical calculation can be attributed to partial hydrolysis before or during the analysis.
• a 500 ml three-necked flask is used equipped with a mechanical stirrer, a dropping funnel and a thermometer; 200 ml of toluene, 34.48 g of aminopropyltriethoxysilane (0.156 mole) and 16 g of triethylamine (0.158 mole) are introduced there.
• the temperature of the reaction medium is lowered to -15 ° C.
• Malonyl dichloride is added dropwise so that the temperature does not exceed -5 ° C.
• the temperature is allowed to return to ambient and the stirring is maintained for 12 hours.
• Step 2 synthesis of N, N, N ', N' tetraethyl-2-propen-1-yl-1, 3 propanediamide (7b)
• THF is removed using a rotary evaporator.
• the residual liquid is redissolved in dichloromethane, washed with water, dried over magnesium sulphate and then again evaporated using the rotary evaporator and the vacuum ramp.
• Step 3 synthesis of N, N, N ', N' tetraethyl-2-propyltriethoxysilyl-1,3 propanediamide (7)
• Examples 6 to 25 which follow illustrate the synthesis of hybrid silica gels according to the invention. They are synthesized by hydrolysis and catalytic polycondensation (NH 4 F) of the functionalized alkoxysilanes of table 1 with optionally tetraethoxysilane Si (OEt) 4 .
• NH 4 F catalytic polycondensation
• ethanol is used as solvent, water for hydrolysis, and NH 4 F as catalyst in the following amounts: - ethanol: 1 ml per mmol of silicon;
• the reaction is carried out at room temperature in a schlenk equipped with magnetic stirring. Water and catalyst are added last. The medium is left to stand until it gels, then it is left to age for a week. The gel is then subjected to the following treatments. Ethanol is removed by vacuum heating the gel
• the amounts of reagents used are as follows: 5.75 g of 1 to 50% alkoxysilane in methanol
• the amounts of reagents used are as follows: 3.4 g of the alkoxysilane 5 (6.67 mmol); 16 ml of ethanol; 432 mg H 2 0 (20 mmol); 16 ⁇ l of NH 4 F 1M (16 ⁇ moles).
• T 3 T 3 > T 2 "X;
• BET S "0.1 m 2 / g;
• Example 16 Preparation of hybrid silica gel 12d.
• Example 17 Preparation of the 12th hybrid silica gel The amounts of reagents used are as follows:
• the amounts of reagents used are as follows: 4.1 g of the alkoxysilane 5 (9.6 mmol); 9.98 g of Si (OEt) (48 mmol); 67 ml of ethanol; 2.25 g H 2 0 (0.125 mole); 67 ⁇ l of NH F IM (67 ⁇ moles). After eleven days, the gelation still having not taken place, 270 ⁇ l of NH 4 F IM are then added. Similarly, after fourteen days, 700 ⁇ l of NH 4 F are still added. The gelling then takes place in the hours that follow. After treatment, 5.2 g are recovered.
• the amounts of reagents used are as follows: 740 mg of the alkoxysilane 6 (2.4 mmol); 2.01 g of Si (OEt) 4 (9.67 mmol); 12 ml of ethanol; 440 mg H0 (24.4 mmol); 24 ⁇ l of NH 4 F IM (24 ⁇ moles). In less than 14 hours, a light yellow translucent gel is obtained. The gel is treated as previously described.
• the hybrid silica gels synthesized from the urea and pyridine alkoxysilanes (examples 6 to 12) or propane diamides (examples 13 to 23) monosilylated are mesoporous materials for values of n greater than about 4 or 5.
• the specific surfaces are then greater than 100 m 2 / g and the diameter distribution of the pores is relatively homogeneous. Depending on the materials, the average diameter varies from 30 to 110 A. More "organic" materials cannot be considered porous (S ⁇ 10 m 2 / g).
• SiCH 2 CH 2 SiCH 2 CH 2
• 40.29 NCH 2
• 50.64 residual SiOCH 3
• gel 15a prepared in Example 24 is used to extract americium from a nitric solution containing 13 mg / l of americium and the influence of nitric acidity on the extraction in the range of ion concentrations (H + ) from 0 to 1.
• the measurements on the solution are carried out by counting ⁇ .
• the difference is made between the amount of the element in the solution at the start and the amount of the element in the solution after the extraction.
• FIG. 1 represents the evolution of the partition coefficient Kd 25 of americium, as a function of the acidity.
• Example 26 the same procedure is followed as in Example 26 for extracting the plutonium from an aqueous solution of nitric acid. containing 131 mg / l Pu, also using gel 15a prepared in Example 24.
• FIG. 2 represents the evolution of the partition coefficient Kd of plutonium as a function of the acidity in the range of concentrations of ions [H + ] from 0 to 6.
• Kd of Pu, Am and Nd as a function of nitric acidity in the nitric acid concentration range from 0 to
• Example 26 the same procedure is followed as in Example 26 for extracting americium from an aqueous solution of nitric acid containing 13 mg / 1 of Am, but the gel 12a prepared in Example 13 in an amount of 60 to 80 g, and a contact time of 120 min.
• FIG. 4 represents the evolution of the partition coefficient Kd of americium as a function of the concentration of nitric acid in the range from 0 to 6 mol / 1.
• the gels of the invention are therefore of great interest because they make it possible, depending on the nature of the gel and the acidity of the aqueous solution, to extract and separate the actinides and lanthanides between them, then to recover by elution in nitric solutions.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Silicon Polymers (AREA)
• Polymers With Sulfur, Phosphorus Or Metals In The Main Chain (AREA)

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• 1997
  • 1997-10-29 FR FR9713565A patent/FR2770153B1/fr not_active Expired - Lifetime
• 1998
  • 1998-10-28 GB GB0009736A patent/GB2349347B/en not_active Expired - Fee Related
  • 1998-10-28 WO PCT/FR1998/002309 patent/WO1999021654A1/fr not_active Ceased
  • 1998-10-28 JP JP2000517801A patent/JP2001520932A/ja active Pending
  • 1998-10-28 KR KR10-2000-7004656A patent/KR100531108B1/ko not_active Expired - Fee Related
  • 1998-10-28 US US09/530,133 patent/US6667016B1/en not_active Expired - Fee Related
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