SOLID MATERIAL HAVING AN OPEN MULTIPLE POROSITY, COMPRISING A GEOPOLYMER AND SOLID PARTICLES, AND METHOD FOR THE PREPARATION THEREOF

Abstract

Solid material having an open multiple and at least partially interconnected porosity, comprising an inorganic matrix made of a microporous and mesoporous geopolymer, in which at least partially interconnected open macropores delimited by sides or walls made of microporous and mesoporous geopolymer are defined, and particles of at least one solid compound different from the geopolymer being distributed in the macropores and/or in the sides or walls. Method for preparing said material. Method for separating at least one metal or metalloid cation from a liquid medium containing it, wherein said liquid medium is placed in contact with the material.

Claims

1. Solid material having an open multiple and at least partially interconnected porosity, comprising a matrix made of a microporous and mesoporous geopolymer, in which at least partially interconnected open macropores delimited by sides or walls made of microporous and mesoporous geopolymer are defined, and particles of at least one solid compound different from the geopolymer being distributed in the macropores and/or in the sides or walls.

2. Material according to claim 1 which is in the form of particles such as grains, granules, or beads; or in the form of a monolith; especially of from 300 .Math.m to a ten or several tens of cm in size, for example 10, 30, 40, 50, or even 100 cm.

3. Material according to claim 1, wherein the particles of the at least one solid compound different from the geopolymer have an average size, such as a diameter, from 2 nm to 100 .Math.m, preferably from 10 nm to 10 .Math.m.

4. Material according to claim 3, wherein the particles of at least one solid compound different from the geopolymer are chosen among the group consisting of nanometric particles, submicronic particles, and micrometric particles.

5. Material according to claim 1 wherein the particles of at least one solid compound different from the geopolymer are active particles.

6. Material according to claim 5, wherein the active particles are chosen among the group consisting of particles of at least one solid metal cation exchanger compound, catalyst particles, and adsorbent compound particles.

7. Material according to claim 6, wherein the solid metal cation exchanger compound is chosen among the group consisting of zeolites; alkaline silicotitanates; coordination polymer (Metal-Organic Frameworks) particles, and mixtures thereof.

8. Material according to claim 1, wherein the amount of particles of at least one solid compound different from the geopolymer is from 0.1 to 30% by mass, preferably from 5 to 15% by mass of the total mass of the material.

9. Method for preparing the material according to claim 1, which comprises at least the following successive steps: a) preparing, by mechanical stirring with shearing of a mixture comprising an oily phase and an aqueous phase, an oil-in-water emulsion formed of droplets of the oily phase dispersed in the continuous aqueous phase, the aqueous phase comprising an activation solution, an aluminosilicate source capable of forming a geopolymer by dissolution/polycondensation and optionally a surfactant, and particles of at least one solid compound being present at the interface formed by the continuous aqueous phase and the droplets of the oily phase dispersed in the continuous aqueous phase of the emulsion; b) leaving the emulsion to stand, and forming it and shaping it to obtain a chosen size and shape, and the geopolymer matrix is formed by polycondensation; c) removing the oily phase, and thus obtaining the material according to claim 1.

10. Method according to claim 9, wherein the oily phase of the mixture consists of one or more linear or branched alkanes having from 7 to 22 carbon atoms, preferably from 12 to 16 carbon atoms, such as dodecane and hexadecane.

11. Method according to claim 9, wherein, prior to step a), the following successive substeps a1) to a4) are carried out to prepare the mixture comprising an oily phase and an aqueous phase: a1) preparing an aqueous solution of particles of at least one solid compound, in water or in an aqueous solution comprising a surfactant; a2) adding an oily phase to the aqueous suspension of particles obtained at the end of step a1), whereby a biphasic mixture comprising the oily phase and an aqueous phase consisting of the aqueous suspension is obtained; a3) adding an aqueous activation solution to the aqueous phase of the biphasic mixture obtained at the end of step a2); a4) adding an aluminosilicate source capable of forming the geopolymer by dissolution/polycondensation, to the aqueous phase of the biphasic mixture obtained at the end of step a3).

12. Method according to claim 11, wherein following step a2), and before step a3), the biphasic mixture comprising the oily phase and an aqueous phase consisting of the aqueous suspension undergoes mechanical stirring with shearing; and/or following step a3) and before step a4), the biphasic mixture undergoes mechanical stirring with shearing.

13. Use of the material according to of claim 1, for catalysing chemical reactions, for filtering a fluid, or for separating or extracting substances contained in a fluid.

14. Method for separating at least one metal cation or metalloid cation from a liquid medium containing it, wherein said liquid medium is placed in contact with the material according to claim 1.

15. Method according to claim 14, wherein the liquid medium is an aqueous liquid medium, such as an aqueous solution.

16. Method according to claim 14 , wherein said liquid medium is chosen from liquids and effluents from nuclear industry and installations and activities using radionuclides.

17. Method according to claim 14, wherein said cation is present at a concentration from 0.1 picogram to 500 mg/L, preferably from 0.1 picogram to 100 mg/L.

18. Method according to claim 14, wherein the cation is a cation of an element chosen among alkali metals, alkaline-earth metals, transition metals, heavy metals, rare earths, actinides, rare gases, and isotopes, particularly radioactive isotopes, thereof.

19. Method according to claim 14, wherein the cation is a cation of an element chosen among Sr, Cs, Co, Ag, Ru, Fe and Tl and isotopes, especially radioactive isotopes thereof.

20. Method according to claim 19, wherein the cation is a cation of .sup.134Cs, or of .sup.137CS, or of .sup.90Sr.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0179] [FIG. 1] is an image taken with a Scanning Electron Microscope (SEM) of the submicronic particles of zeolite LTA prepared in example 1.

[0180] The scale applied in FIG. 1 represents 1 .Math.m.

[0181] [FIG. 2] is a photograph of the monolith, comprising a geopolymer incorporating submicronic particles of zeolite LTA, prepared in example 1 using the protocol P0.

[0182] [FIG. 3A] and

[0183] [FIG. 3B] show SEM images of the inside of the monoliths prepared in example 1 and in example 1A respectively.

[0184] The scale applied in FIGS. 3A and 3B represents 70 .Math.m.

[0185] [FIG. 4] is a graph which shows the pore size distribution in a pure synthesised geopolymer (Example 1B) (curve A), and in two geopolymers synthesised with P0 with zeolite (Example 1) (curve B), and with P0 without zeolite (Example 1A) (curve C).

[0186] The x-axis shows the pore diameter (in nm) and the y-axis shows dV/dlog(D) Porous volume (in cm.sup.3/g.nm).

[0187] [FIG. 5] is a graph showing the diffractograms of submicronic zeolite LTA (curve A), of a geopolymer without zeolite synthesised with P0 (Example 1A) (curve B) and of a geopolymer including zeolite LTA synthesised with P0 (Example 1) (curve C).

[0188] The x-axis shows 2 theta (in °) and the y-axis shows the intensity (in arbitrary units).

[0189] [FIG. 6A] [FIG. 6B] and [FIG. 6C] show SEM images of the geopolymer monoliths prepared in example 2, according to protocol P1 (FIG. 6A), protocol P2 (FIG. 6B) and protocol P3 (FIG. 6C). The scale applied in FIGS. 6A, 6B and 6C represents 70 .Math.m.

[0190] [FIG. 7] is a graph showing the pore size distribution in the monoliths prepared in example 2 with protocols P1, P2 and P3.

[0191] The x-axis shows the pore diameter (in nm) and the y-axis shows dV/dlog(D) Porous volume (in cm.sup.3/g.nm).

[0192] [FIG. 8] is a bar graph showing the values of Kd (in mL/g) (example 3) determined for a geopolymer zeolite (without submicronic zeolite particles) prepared according to protocol P0, and for geopolymer monoliths, (comprising zeolite particles) prepared according to protocols P0, P1, P2 and P3.

[0193] [FIG. 9] is an SEM image of the micronic zeolite particles used in example 4.

[0194] The scale applied in FIG. 9 represents 5 .Math.m.

[0195] [FIG. 10] is a graph showing the diffractograms (example 4B) of the micronic particles of zeolite 4A (curve A), of a geopolymer without particles of zeolite 4A prepared according to protocol P3 (curve B), and of a geopolymer including particles of zeolite 4A prepared according to protocol P3 (curve C).

[0196] The x-axis shows 2 theta (in °) and the y-axis shows the intensity (in arbitrary units).

[0197] [FIG. 11] is a graph showing the particle size distribution analysis of the nanometric particles of CST used in example 5.

[0198] The x-axis shows the size (in .Math.m), and the y-axis shows the % (in number).

[0199] [FIG. 12] is a graph showing the diffractograms (Example 5B) of nanoparticles of CST (curve A), of a geopolymer without CST prepared according to protocol P3 (curve B) and of a geopolymer including nanoparticles of CST prepared according to protocol P3 (curve C).

[0200] [FIG. 13] is a graph showing the nitrogen adsorption isotherm produced on the pure geopolymer. The x-axis shows the relative pressure (P/P°), and the y-axis shows the quantity of nitrogen adsorbed (in cm.sup.3/g).

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

[0201] The invention will now be described with reference to the following examples, given by way of illustration and not limitation.

EXAMPLES

Example 1

[0202] In this example, the manufacture, according to the invention, of a monolithic material comprising a geopolymer incorporating a submicronic zeolite is carried out.

[0203] More precisely, in this example, according to the invention, submicronic particles of zeolite LTA (known to be an effective and selective adsorbent of Sr in aqueous medium) are incorporated within a macroporous geopolymer matrix, “skeleton”.

[0204] Synthesis of submicronic particles of zeolite LTA.

[0205] The protocol for synthesising submicronic particles of zeolite LTA is as follows: [0206] 2.65 g of NaOH pellets (marketed by Sigma-Aldrich®), and 5.75 g of NaAlO.sub.2 powder (marketed by VWR®), are dissolved separately in 26.25 mL and 35 mL of water respectively. [0207] The two solutions are then mixed in an autoclave under vigorous stirring for a few minutes. [0208] 2 g of SiO.sub.2 powder (Aerosil ® 380 available from Evonik Industries®) is then added in the autoclave, and the autoclave is hermetically sealed. [0209] A heat treatment at 40° C. for 20 h, then at 70° C. for 24 h, is applied. [0210] The powder obtained is finally retrieved by filtration, washed with water, and dried overnight at 80° C.

[0211] Submicronic particles of zeolite LTA between 300 and 500 nm in size are finally obtained (see FIG. 1).

[0212] Manufacture of the material in the form of a monolith, comprising a geopolymer incorporating the submicronic particles of zeolite LTA.

[0213] The protocol for synthesising the material comprising a geopolymer incorporating the submicronic particles of zeolite LTA synthesised as described above is the following protocol P0 and which firstly comprises the successive steps: [0214] Step 1: 617 mg of zeolite LTA powder (consisting of submicronic particles) are added to 1.774 mL of an aqueous solution concentrated to 34.8 g.L.sup.-1 with surfactant, that is to say Tetradecyltrimethylammonium Bromide (TTAB) (marketed by Sigma-Aldrich®). The concentrated aqueous solution to which the powder was added is placed for 15 minutes in an ultrasound bath. [0215] Step 2: Addition, to the concentrated aqueous solution to which the powder was added, of 5 mL of oily phase, that is to say dodecane (marketed by Sigma-Aldrich®). [0216] Step 3: Addition of 2.12 mL of a solution composed of 81% by mass of a commercial inorganic binder called Betol® K5020T (available from Wöllner®) based on a modified potassium silicate aqueous solution, and composed of 30% by mass of SiO.sub.2 18% by mass of K.sub.2O, and 52% by mass of H.sub.2O; and of 19% by mass of KOH (85%, marketed by Sigma-Aldrich®). [0217] Step 4: Addition of 2.64 g of Metakaolin powder (Metamax® from BASF) [0218] So-called “UT” step 5: the mixture is finally sheared for 1 minute using an Ultra-Turrax® homogeniser equipped with an S25N-18G dispersion head at a shear rate of 10000 rpm.

[0219] An emulsion is thus obtained, at the end of step 5.

[0220] This viscous emulsion is placed in a cylindrical mould of one cm in diameter that is left to stand, rest for 48 h.

[0221] After mould release, a solid monolithic cylindrical material of approximately 4 cm in height and 1 cm in diameter is obtained.

[0222] This monolithic material is then washed with a Soxhlet extractor with a 50-50 THF-acetone mixture to remove the dodecane, then is left to dry at 80° C.

[0223] After 24 h of drying, the solid and robust monolith, having retained the dimensions thereof, is obtained (FIG. 2).

Example 1A

[0224] In this example, a material in the form of a monolith similar to that of example 1, but not including submicronic particles of zeolite LTA, is manufactured. This monolith is synthesised according to the same protocol, called protocol P0, as in example 1.

Example 1B

[0225] In this example, a pure geopolymer (pure synthesised geopolymer) is manufactured, i.e. according to protocol P0, but without submicronic zeolite, without TTAB, and without adding oil to form an emulsion.

[0226] The geopolymer obtained has a specific surface area of 71.3 m.sup.2.g.sup.-1.

Example 1C

[0227] In this example, the materials prepared in examples 1, 1A, and 1B are characterised.

[0228] The interior of the two monoliths prepared in example 1 and in example 1A is observed by scanning electron microscopy (SEM).

[0229] The images obtained are shown in FIGS. 3A and 3B.

[0230] It is observed that: [0231] In the absence of zeolite particles, the material has alveolar pores with no (or very little) interconnections. [0232] In the presence of zeolite, the microstructure of the material is completely different. The pores no longer have an alveolar structure and the interconnection thereof is enhanced.

[0233] The monoliths prepared in examples 1 and 1A are analysed, by nitrogen adsorption-desorption in order to determine the specific surface area thereof (BET model) and the pore size distribution (< 60 nm, BJH model).

[0234] Specific surface areas of 34.4 and 37.8 m.sup.2.g.sup.-1 are measured for the geopolymers respectively with (material of example 1) and without zeolite (material of example 1A).

[0235] FIG. 4 shows the mesopore size distributions in both materials.

[0236] This figure also represents the mesopore size distribution of the pure geopolymer, prepared in example 1B.

[0237] It is observed that the pure synthesised geopolymer (Example 1B) and the material prepared using protocol P0 without zeolite (Example 1A) have pore size distributions centred around 19-20 nm, whereas the material synthesised using protocol P0 with zeolite (Example 1 according to the invention), has a pore size distribution centred around 27 nm.

[0238] The presence of zeolite in the formulation is thus capable of increasing the size of the mesopores.

[0239] FIG. 13 shows the adsorption isotherm of the pure geopolymer. This isotherm has a type IV shape in the IUPAC classification and demonstrates the presence of micropores in the structure of the geopolymer due to the shape of the curve at low pressures.

[0240] The two monoliths prepared in example 1 and in example 1A are then ground in powder form and an X-ray diffraction (XRD) analysis is then performed.

[0241] An XRD analysis is also performed on the pure submicronic zeolite LTA powder.

[0242] The results of these analyses are shown in FIG. 5.

[0243] (NB: in FIG. 5, “pure geopolymer” is mentioned: this is the geopolymer synthesised without submicronic zeolite, without TTAB and without adding oil to form an emulsion (geopolymer of example 1B)).

[0244] The 3 diffractograms shown in FIG. 5 demonstrate that the submicronic particles of zeolite LTA have, in the material prepared in example 1, according to the invention, indeed been incorporated in the structure of the macroporous geopolymer.

Example 1D

[0245] In this example, the effectiveness of the material prepared in example 1 according to the invention, and of the material prepared in example 1A for decontaminating effluents containing Strontium (Sr) was studied.

[0246] In other words, in this example, the material prepared in example 1 according to the invention, and the material prepared in example 1A were tested in the context of an application as an Sr-adsorbent material.

[0247] Sorption tests of Sr in solution are therefore performed to make it possible to validate that the zeolite LTA inserted in the geopolymer skeleton in the material prepared in example 1 is indeed active.

[0248] The parameter used to monitor Strontium sorption is Kd (distribution coefficient in mL/g) calculated according to the following formula:

[00001]$K_D=\frac{\left({\left[Sr\right]}_{init}-{\left[Sr\right]}_{fin}\right)}{{\left[Sr\right]}_{fin}}\frac{V}{m}$

[0249] In this formula: [0250] [Sr].sub.init and [Sr].sub.fin respectively represent the initial and final Sr concentration in solution (mg/L), [0251] V is the solution volume (mL), [0252] m is the material mass (g).

[0253] The protocol used for these sorption tests is as follows: [0254] 50 mg of material (in monolithic form) are placed in 50 mL of a matrix (aqueous solution) containing 0.05 mol/L of NaNO.sub.3, 50 ppm of Ca (added in the form of the salt Ca(NO.sub.3).sub.2), 2 ppm of Cs (added in the form of the salt CsNO.sub.3) and 2 ppm of Sr (added in the form of the salt Sr(NO.sub.3).sub.2). [0255] The whole is stirred with a rotary stirrer for 24 h. [0256] After stirring, 15 ml of supernatant is extracted with a syringe, and this sample is filtered with a 0.22 .Math.m syringe filter, then the residual Sr concentration is analysed by inductively coupled plasma (ICP) spectrometry.

[0257] The geopolymer monolith free from zeolite (Example 1A) has a Kd of 1128 mL/g while the geopolymer monolith containing the particles of zeolite LTA (Example 1 according to the invention) has a Kd of 5024 mL/g.

[0258] This result demonstrates that the particles of zeolite LTA incorporated in the macroporous geopolymer (Example 1 according to the invention) allow highly improved decontamination, virtually of a factor of 5.

[0259] This result clearly shows the accessibility of the zeolite particles by the contaminated effluent.

Example 2

[0260] In this example, a monolithic material comprising a geopolymer incorporating a submicronic zeolite is prepared by various methods in order to study the influence of the manufacturing method on the macroporosity of the monolithic material.

[0261] Thus, in order to observe the influence of the manufacturing method on the macroporosity of the material and the interconnectivity of the macropores, one or two additional steps called “UT” steps were added to the different steps of the protocol P0 (called steps 1, 2, 3, 4 and 5 (“UT”) in example 1).

[0262] 3 new protocols, called protocols P1, P2 and P3, were therefore tested and are described in Table 1 below.

[0263] The quantities of material added are similar to those used in example 1. The final materials obtained using protocols P0, P1, P2 and P3 therefore have exactly the same final chemical compositions.

TABLE-US-00001 Description of the different steps of protocols P1, P2 and P3 P1 P2 P3 1, 2, UT, 3, 4, UT 1, 2, UT, 3, UT, 4, UT 1, 2, 3, UT, 4, UT

[0264] It is important to note that the description of protocols P0, P1, P2, P3 and P4 given here in the specific context of example 1 and example 2 can be readily generalised and that especially the specific conditions of the different steps can be readily generalised with regard to the “description of the invention” given above.

[0265] Regardless of the protocol used, an emulsion is systematically stabilised then placed in a mould and left to stand for 48 h to obtain the setting of the geopolymer skeleton and the formation of a cylindrical monolith of a few centimetres in heights and 1 cm in diameter.

[0266] After washing for a 24 h duration in the Soxhlet extractor with a 50-50 THF-acetone mixture to remove the dodecane, the monolith is left to dry for 24 h at 80° C.

[0267] The inside of each of the monoliths obtained is then observed by scanning electron microscopy (SEM).

[0268] The images obtained are shown in FIGS. 6A, 6B and 6C.

[0269] It is observed that: [0270] Protocol P1 (FIG. 6A) produces so-called “alveolar” materials wherein the pores seem to be slightly interconnected. [0271] Protocol P2 (FIG. 6B) generates an intermediate microstructure with alveolar pores residues, as well as the presence of non-alveolar and more interconnected pores. [0272] Protocol P3 (FIG. 6C) produces for its part a large majority of non-alveolar and highly interconnected pores

[0273] The monoliths are analysed by nitrogen adsorption-desorption in order to determine the specific surface area thereof (Brunauer, Emmett and Teller model, “BET”) and the pore size distribution thereof (< 60 nm, Barrett, Joyner, Halenda model, “BJH”).

[0274] Specific surface areas of 33.1, 30.6 and 31.5 m.sup.2.g.sup.-1 are measured for the materials prepared with protocols P1, P2 and P3 respectively.

[0275] FIG. 7 shows the pore size distributions (< 60 nm) in the three materials.

[0276] The pore size distribution of each material is centred on 27 nm, like that obtained for the material synthesised using P0 with zeolite.

[0277] The modification of the synthesis protocol therefore does not appear to have any influence on the mesopores size distribution.

[0278] Thus, these results clearly demonstrate an influence of the inversion of the manufacturing steps on the macroporosity and interconnectivity of the macropores of the material, without modifying the mesoporosity of the walls.

[0279] These results show that protocol P3 is the preferred protocol, then, in order, protocol P0 then protocol P2, and finally protocol P1.

Example 3

[0280] In this example, the influence of the manufacturing method on the decontamination effectiveness of the monolithic material comprising a geopolymer containing submicronic zeolite LTA particles is studied.

[0281] For this, the effectiveness of the materials prepared according to protocols P1, P2 and P3 for decontaminating effluents containing Strontium was studied.

[0282] Similar “batch” studies to those conducted in example 1D were performed.

[0283] FIG. 8 shows the Kd values obtained with the materials prepared by protocols P1, P2 and P3.

[0284] FIG. 8 also shows the Kd value obtained with the geopolymer monolith without zeolite (prepared in example 1A according to protocol P0), Kd of 1128 mL/g: see example 1C) as well as the Kd value obtained with the geopolymer monolith containing zeolite LTA particles and prepared according to protocol P0 (Example 1 according to the invention, Kd of 5024 mL/g: see example 1D).

[0285] In FIG. 8, a clear difference between the Kd values is observed, which is due to the different internal porous microstructures of the materials rendering the active zeolite particles more or less accessible to the effluent to be decontaminated.

[0286] Thus: [0287] The materials prepared according to protocols P0 and P3 have non-alveolar and more interconnected microstructures and have higher Kd values. [0288] The material prepared according to protocol P1 has a highly alveolar and less interconnected structure and has a Kd only two times greater than that of the material free from zeolite. [0289] The material prepared according to protocol P2 has an intermediate microstructure, hence inducing an intermediate Kd.

[0290] Once again: these results show that protocol P3 is the preferred protocol, then, in order, protocol P0 then protocol P2, and finally protocol P1.

Example 4

[0291] In this example, the manufacture, according to the invention, of a monolithic material comprising a geopolymer incorporating a zeolite of micronic size is carried out.

[0292] More precisely, in this example, according to the invention, micronic particles of zeolite 4A (known to be an effective and selective adsorbent of Sr in aqueous medium) are incorporated within a macroporous geopolymer matrix.

[0293] The micronic particles of zeolite 4A are commercial particles manufactured by the company CTI (Ceramiques Techniques Industrielles).

[0294] FIG. 9 shows an SEM image of these particles, the size of which is between 4 and 5 .Math.m.

[0295] Manufacturing protocol P3 (described in example 2) is used, the mass of submicronic zeolite having been replaced by the same mass of micronic zeolite.

[0296] A viscous emulsion is thus obtained, at the end of the final step of protocol P3 (step “UT”).

[0297] This viscous emulsion is placed in a mould that is left to stand for 48 h.

[0298] After mould release, a monolithic material is obtained.

[0299] This monolithic material is then washed with a Soxhlet extractor with a 50-50 THF-acetone mixture to remove the dodecane, then it is left to dry at 80° C.

[0300] After 24 h of drying, a cylindrical monolith of a few centimetres in height and 1 cm in diameter is obtained.

[0301] The monolith is then ground in powder form. An X-ray diffraction (XRD) analysis is then carried out.

Example 4A

[0302] In this example, a material in the form of a monolith similar to that of example 4, but not including micronic particles of zeolite 4A, is manufactured. This monolith is synthesised according to the same protocol, called protocol P3, as in example 4, but without micronic zeolite, without TTAB and without adding oil to form an emulsion.

[0303] The monolith is then ground in powder form. An X-ray diffraction (XRD) analysis is then carried out

Example 4B

[0304] In this example, an X-ray diffraction (XRD) analysis of the powders obtained at the end of examples 4 and 4A is carried out.

[0305] An XRD analysis is also performed on the micronic zeolite 4A powder.

[0306] The results of these XRD analyses are shown in FIG. 10.

[0307] (NB: in FIG. 10, “pure geopolymer” is mentioned: this is the geopolymer synthesised without micronic zeolite, without TTAB and without adding oil to form an emulsion (geopolymer of example 4A)).

[0308] The three diffractograms shown in FIG. 10 demonstrate that the micronic zeolite 4A particles have indeed been incorporated in the structure of the macroporous geopolymer.

Example 4C

[0309] In this example, the effectiveness of the material prepared in example 4 according to the invention for decontaminating effluents containing Strontium (Sr) was studied.

[0310] For this, a similar “batch” test to those conducted in example 1D was performed.

[0311] A Kd of 5528 mL/g, greater than the Kd of 1128 mL/g of a geopolymer free from active particles (see example 1D) is obtained, demonstrating the effectiveness of the material.

Example 5

[0312] In this example, the manufacture, according to the invention, of a monolithic material comprising a geopolymer incorporating nanometric crystalline silico-titanate (CST) particles is carried out.

[0313] More precisely, in this example, according to the invention, nanometric particles of crystalline silico-titanates (CST) (known to be an effective and selective adsorbent of Sr in aqueous medium) are incorporated within a macroporous geopolymer “skeleton” matrix.

[0314] The nanometric CST particles are commercial particles manufactured by the company UOP.

[0315] FIG. 11 shows a laser particle size distribution analysis of these particles which shows that the size thereof is between about 10 and 20 nm in solution after dispersion with ultrasounds.

[0316] Manufacturing protocol P3 (described in example 2) is used, the mass of submicronic zeolite having been replaced by the same mass of CST.

[0317] A viscous emulsion is thus obtained, at the end of the final step of protocol P3 (step “UT”).

[0318] This viscous emulsion is placed in a mould that is left to stand for 48 h.

[0319] After mould release, a monolithic material is obtained.

[0320] This monolithic material is then washed with a Soxhlet extractor with a 50-50 THF-acetone mixture to remove the dodecane, then it is left to dry at 80° C.

[0321] After 24 h of drying, a cylindrical monolith of a few centimetres in height and 1 cm in diameter is obtained.

[0322] The monolith is then ground in powder form.

Example 5A

[0323] In this example, a material in the form of a monolith similar to that of example 5, but not including nanometric CST particles, is manufactured. This monolith is synthesised according to the same protocol, called protocol P3, as in example 5.

[0324] The monolith is then ground in powder form.

Example 5B

[0325] In this example, an X-ray diffraction (XRD) analysis of the powders obtained at the end of examples 5 and 5A is carried out.

[0326] An XRD analysis is also performed on the nanometric CST powder.

[0327] The results of these XRD analyses are shown in FIG. 12.

[0328] (NB: in FIG. 12, pure geopolymer is mentioned: this is a geopolymer synthesised without CST, without TTAB and without adding oil to form an emulsion (geopolymer of example 4A)).

[0329] These 3 diffractograms demonstrate that the nanometric CST particles have indeed been incorporated in the structure of the macroporous geopolymer.

Example 5C

[0330] In this example, the effectiveness of the material prepared in example 5 according to the invention for decontaminating effluents containing Strontium (Sr) was studied.

[0331] For this, a “batch” test similar to those conducted in example 1D is performed.

[0332] A Kd of 4732 mL/g, greater than the Kd of 1128 mL/g of a geopolymer free from active particles (see example 1D) is obtained, demonstrating the effectiveness of the material.

REFERENCES

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