METHOD FOR PREPARING A FUNCTIONALISED GEOPOLYMER INVOLVING 3D PRINTING, SAID GEOPOLYMER AND ITS USES

Abstract

A method for preparing a geopolymer capable of trapping at least one ion, may include, firstly, preparing a geopolymer including at least one 3D printing, then functionalizing the geopolymer thus prepared by at least one extractant group, the group not including an NH.sub.2 amine function. Such a functionalized geopolymer thus prepared may be used to separate at least one ion from a flow containing the at least one ion.

Claims

1. A method for preparing a geopolymer capable of ion trapping, the method comprising: preparing a geopolymer comprising 3D printing, to obtain a prepared geopolymer; and functionalizing the prepared geopolymer with a functionalization comprising an extractant group specific to an ion, wherein the extractant group does not have an NH.sub.2 amine function.

2. The method of claim 1, wherein the geopolymer is mesoporous.

3. Method according to claim 1, wherein the geopolymer is a foam.

4. The method of claim 1, wherein the extractant group comprises: an ammonium of formula N(R.sub.1) (R.sub.2) (R.sub.3) with R.sub.1, R.sub.2, and R.sub.3, independently being H, an alkyl radical, or an aryl radical; an amine of formula N(R.sub.4)(R.sub.5) with R.sub.4 and R.sub.5 independently being H, an alkyl radical, or an aryl radical, provided that, when R.sub.4 is H, R.sub.5 is not H; an amide of formula C(O)N(R.sub.6) (R.sub.7) or -N(R.sub.6)C(O)-(R.sub.7) with R.sub.6 and R.sub.7 independently being H, an alkyl radical, or an aryl radical; a phosphorus function of formula X.sub.2-P(-X.sub.1).sub.n(X.sub.3R.sub.8)(X+R.sub.9) with n being 0 or 1, X.sub.1 being O or S, X.sub.2, X.sub.3, and X.sub.4, independently being a chemical bond, O, S, or a -CR.sub.10R.sub.11- group, R.sub.8 and R.sub.9 independently being H, an alkyl radical, or an aryl radical, and R.sub.10 and R.sub.11 independently being H or an alkyl radical; a diglycolamide of formula N(R.sub.12)C(O)CH.sub.2OCH.sub.2C(O)N(R.sub.13)(R.sub.14) with R.sub.12, R.sub.13, and R.sub.14 independently being an alkyl radical or an aryl radical; an amine or polyamine of formula -[N(CH.sub.2COOH)-C.sub.2H.sub.4].sub.mN(CH.sub.2COOH).sub.2 with m being 0 or an integer; a sulfonic acid of formula -(CH.sub.2).sub.p(SO.sub.3H) with p being 0 or an integer; a urea of formula NR.sub.15C(O)N(R.sub.16) (R.sub.17) with R.sub.15, R.sub.16, and R.sub.17 independently being H, an alkyl radical, or an aryl radical; and/or a macromolecular or polydentate function.

5. The method of claim 1, wherein the functionalization of the geopolymer by at least one-the extractant group is direct.

6. The method of claim 1, wherein the functionalization of the geopolymer by the extractant group is indirect, comprising a connector bound, on a first side, to a surface of the geopolymer and, on a second side, to the extractant group.

7. The method of claim 1, geopolymer wherein the preparing comprises: (a1) preparing a geopolymer mixture; (b1) 3D printing the geopolymer mixture from the preparing (a1), to obtain a printed geopolymer; and (c1) allowing the printed geopolymer from the 3D printing (b1) to harden, thereby obtaining a geopolymer.

8. The method of claim 1, wherein the preparing comprises: (a2) preparing, by 3D printing, a sacrificial support; (b2) placing the sacrificial support from the preparing (a2) in contact with a previously prepared geopolymer mixture, to obtain a contacted geopolymer mixture; (c2) allowing the contacted geopolymer mixture to harden in contact with the sacrificial support; and (d2) eliminating the sacrificial support, thereby obtaining a geopolymer.

9. The method of claim 1, wherein the functionalization comprises: (i) placing the geopolymer in contact with a molecule comprising the extractant group and a reactive function in conditions allowing at least one covalent bond to form between the molecule and the geopolymer, to obtain a reacted geopolymer; and (ii) eliminating said unreacted molecule from the placing (i), thereby obtaining a functionalized geopolymer comprising the extractant group.

10. A geopolymer capable of trapping at least one ion, the geopolymer prepared by the method of claim 1, wherein the geopolymer is mesoporous with optionally non-connected macropores or a foam and is functionalized, directly or indirectly, by an extractant group specific to at least one ion, and wherein the extractant group does not comprise an NH.sub.2 amine function.

11. A method for ion separation from a flow, the method comprising: contacting a first flow comprising an ion and the geopolymer of claim 10, thereby separating the ion from the first flow to obtain a second flow, comprising the ion in a lesser amount, and a laden geopolymer comprising the ion affixed via the extractant group to a surfaces of the laden geopolymer.

12. The method of claim 11, wherein the flow is an outside air sample, an air sample coming from industries of the chemical, agri-food, pharmaceutical, cosmetic or nuclear field, municipal water, river water, seawater, lake water, an effluent coming from a wastewater treatment plant, wastewater, a household liquid effluent, a medical or hospital liquid effluent, an industrial liquid effluent, or a mixture thereof.

13. The method of claim 11, wherein the ion is a metal or metalloid ion.

14. The method of claim 13, wherein the metal or metalloid ion comprises mercury, gold, silver, platinum, lead, iron, indium, gallium, aluminium, bismuth, tin, cadmium, copper, lithium, arsenic, nickel, zinc, titanium, cobalt, manganese, palladium, curium, americium, radium, ruthenium, thorium, uranium, plutonium, actinium, ytterbium, erbium, terbium, gadolinium, europium, neodymium, praseodymium, cerium, cacsium, thallium, strontium, and/or lanthanum.

15. The method of claim 1, wherein the extractant group comprises: a crown ether, a thioether crown, a calixarene, a porphyrin, a phthalocyanine, a pyrazoline, a phenanthroline, an ethylenediaminetriacetic acid, an ethylenediaminetetraacetic acid (EDTA), a 1,4,7,10 tetraazacyclododecane 1,4,7,10 tetraacetate (DOTA), and/or a diethylene triamine pentaacetate (DTPA).

16. The method of claim 1, wherein the geopolymer is mesoporous with non-connected macropores.

17. The method of claim 1, wherein the extractant group comprises the polyamine of formula -[N(CH.sub.2COOH)C.sub.2H.sub.4].sub.mN(CH.sub.2COOH).sub.2 with m being 1, 2, 3, or 4.

18. The method of claim 1, wherein the extractant group comprises the sulfonic acid of formula -(CH.sub.2).sub.p(SO.sub.3H) with p being 1, 2, 3, 4, or 5.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0144] FIG. 1 is a diagram of the main steps of the method for preparing a geopolymer capable of trapping at least one ion and its use in the decontamination of a liquid effluent containing said at least one ion.

[0145] FIG. 2 presents photographs of the material obtained during the various steps allowing the creation of a geopolymer with controlled porosity. The sample presented has a theoretical porosity of approximately 25% by volume.

[0146] FIG. 3 presents photographs following, in time, the step allowing the creation of a geopolymer with controlled porosity (the sample presented has a theoretical porosity of approximately 25% by volume).

DETAILED DISCLOSURE OF SPECIFIC EMBODIMENTS

I. Method for Preparing a Geopolymer with Controlled Porosity

I.1Method by Direct 3D Printing

[0147] Step 0: Modelling of the percolating network on a computer, the geometry of filling of the part is chosen to correspond to a complex geometry.

[0148] Step 1: Printing of the part on a fused deposition modelling 3D printer (of the FDM type), the filament chosen is a geopolymer formulation corresponding to the following formula expressed in moles: 3.8 SiO.sub.2: 1.0Al.sub.2O.sub.3: 1.0Na.sub.2O: 11.0H.sub.2O. The printing parameters are: [0149] Layer height: 0.5 mm; [0150] Size of the nozzle: 0.8 mm; [0151] Type of filling: gyroid; [0152] Filling rate: 20 to 80%; [0153] No heating of the bed or of the nozzle, the technique amounting to a deposition of geopolymer paste in the fresh state.

I.2. Method by Inverse 3D Printing

[0154] The protocol followed to create a geopolymer via inverse 3D printing is the following: [0155] Step 0: Modelling of the sacrificial backbone on a computer, the geometry of filling of the part is chosen to correspond to a complex geometry. [0156] Step 1: Printing of the part on a fused deposition modelling 3D printer (of the FDM type), the filament chosen is HIPS. The printing parameters are a temperature of 240 C. for the nozzle and 110 C. for the print bed. [0157] Step 2: i. Formulation of a geopolymer mixture, which involves mixing an activation solution and metakaolin in the following proportions corresponding to the formulation expressed in moles: 3.8 SiO.sub.2: 1.0Al.sub.2O.sub.3: 1.0Na.sub.2O: 11.0H.sub.2O. To do this, 54.2 g of BETOL 52T (aluminosilicate source), 0.5 g of water, 2 g of NaOH and 43.3 g of IMERYS M1000 metakaolin are used.

[0158] Then, the whole is placed under stirring in order to guarantee the homogeneity of the geopolymer paste.

[0159] ii. Immersion of the polymer sacrificial backbone in the latter. The sample is then placed under ultrasounds for 30 seconds, in order to remove the residual air bubbles in the geopolymer. Other techniques can be used such as placement under vacuum to remove the residual air bubbles, or the arrangement of a specific mould that would allow to push the paste into the sacrificial backbone (i.e. a suitable syringe). [0160] Step 3: This step involves allowing the composite material (geopolymer comprising the sacrificial backbone) harden for 7 days, which allows the geopolymer to develop sufficient mechanical strength for the following step. A surface preparation of the sample is necessary in order to expose the surface of the sacrificial backbone: the two ends of the geofilter are sectioned with a circular or wire saw to expose the channels of the sacrificial backbone. [0161] Step 4: Freeing the porosity by dissolution of the polymer (HIPS) present in the material. For this, the material is immersed in dichloromethane under stirring, it is left until stabilisation of its mass. The material thus prepared has a controlled porosity.

[0162] Once dried (oven or under air, at a temperature between ambient temperature and 30 C., for a duration between 2 h and 4h), the material is thus ready for the following step of the method (grafting).

[0163] Steps 1 to 4 are illustrated in FIG. 2 in the case of a geopolymer with 25% porosity by volume relative to the total volume (75% of volume occupied by the geopolymer). The photograph of step 1 corresponds to the sacrificial backbone made of HIPS obtained by 3D printing. The photograph of step 2 corresponds to the filling by geopolymer matrix. The photograph of step 3 taken after hardening of the geopolymer corresponds to a transverse cross-section of the material obtained, allowing to view the encapsulation of the sacrificial backbone in the latter. The photograph of step 4 taken after freeing of the porosity after the dissolution of the sacrificial backbone made of polymer corresponds to a transverse cross-section of the geopolymer obtained, allowing to view the porosity of the latter corresponding to the location of the sacrificial backbone.

[0164] FIG. 3 addresses the step 4 of dissolution of the sacrificial backbone made of HIPS, a complex and controlled geometry can be observed inside the material.

II. Method for Functionalisation of this Geopolymer with Controlled Porosity

[0165] The grafting steps are carried out after the step of freeing the porosity.

[0166] The step 0 of pretreatment is optional. However, the step 4 of freeing the porosity of the process Preparation of a geopolymer with controlled porosity can be carried out simultaneously with the step 2 of grafting in the absence of step 0.

[0167] Step 0: Acid pretreatment of the geopolymer filter then drying.

[0168] Immersion of the filter in suspension in a 0.1 M solution of nitric acid at ambient temperature under slight stirring without contact between the stirring mechanism and the filter.

[0169] Immersion of the filter in suspension in a solution of toluene at ambient temperature under slight stirring without contact between the stirring mechanism and the filter. [0170] Step 1: The grafting reactant used is the [3-(diethylamino) propyl] trimethoxysilane having the CAS: 41051-80-3 and the formula:

##STR00009## [0171] Step 2: Grafting of the extractant groups onto the geopolymer by placement in contact and heating of the latter with the grafting reactant in dichloromethane with reflux (40 C.) for one night (1 mmol of grafting reactant/g of geofilter/10 ml of solvent). [0172] Step 3: Washing of the residual impurities using repeated washings in dichloromethane in Soxhlet equipment (150 ml of solvent with reflux for one night on a filter placed in a cellulose cartridge). [0173] Step 4: Drying of the sample in an oven (80 C., one night) the material is then ready to be analysed.

III. Characterisation of the Functionalised Geopolymer Obtained

[0174] It is possible to characterise the geopolymer obtained by the method according to the invention via various techniques. Examples of such techniques include gravimetry, porosimetry (gas, mercury), nuclear magnetic resonance like MAS-NMR (Magic Angle Spinning-NMR), infrared spectroscopy like Fourier-transform infra-red spectroscopy (or FTIR) and DSC (for Differential Scanning calorimetry) coupled with thermogravimetric analysis.

[0175] Table 2 below presents the characterisations after grafting in the case of a geopolymer with 25% porosity by volume, functionalised by the grafting reactant: 3-(diethylamino)propyl]trimethoxysilane, for which the reactant function is trimethoxy silane and the extractant group with a connector is diethylpropyl amine.

[0176] This extractant group can be intended for the extraction of actinides (uranium) from organic solutions, but also be used in the depollution of water of transition metals/metalloids (for example, arsenic, lead, copper, cadmium).

[0177] The overall taking on of mass, coupled with the appearance of the MAS-NMR signals (analysis of the NMR signals obtained directly by analysis of the solid) on the .sup.13C spectra typical of the alkyl chains bound to the amine as well as the reduction in specific surface area (linked to the covering of the surface by the organic functions), confirms the functionalisation by grafting of the porous geopolymer manufactured by inverse 3D.

TABLE-US-00002 TABLE 2 Characterisation proving the functionalisation of a geopolymer with controlled porosity Initial Final characteristics characteristics Mass (g) 6.595 6.815 (3.2% mass taken on) TGA (thermogravimetric 13.4% 13.6% analysis) % mass loss MAS-NMR (.sup.29Si) .sup.29Si: 87.9 .sup.29Si: 60.6 87.2 MAS-NMR (.sup.13C) .sup.13C: 168.8, 166.7, .sup.13C: 170.8, 144.9, 127.9, 127.6, 45.0, 57.6, 47.5, 22.6, 11.3 41.6, 28.3 In bold: high-intensity peaks typical of grafted (CH.sub.2).sub.3N(CH.sub.2CH.sub.3).sub.2 carbons

BIBLIOGRAPHICAL REFERENCES

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