Photoluminescent hybrid organic/inorganic materials and method for preparing same

Abstract

Disclosed is a method for preparing a hybrid organic/inorganic composition including inorganic nanoparticles functionalized by at least one molecule chosen from photoluminescent charged organic molecules, the method including bringing into contact, in a single-phase solvent medium, at least one photoluminescent charged organic molecule and non-swelling phyllosilicate nanoparticles having a thickness of 1 nm to 100 nm, and a larger dimension of 10 nm to 10 μm. Also disclosed are hybrid photoluminescent nanoparticles compositions obtained by this method.

Claims

1. Method for the preparation of an organic/inorganic hybrid composition comprising mineral nanoparticles functionalized by at least one molecule chosen from photoluminescent charged organic molecules, this method comprising at least bringing into contact, in a monophasic solvent medium, of at least one photoluminescent charged organic molecule and non-swelling phyllosilicate nanoparticles having a thickness of 1 nm to 100 nm, and a larger dimension of 10 nm to 10 μm.

2. Method according to claim 1, which comprises at least the following steps: (i) providing a solution (a) of at least one photoluminescent charged organic molecule in at least one solvent, (ii) providing a suspension (b) of non-swelling phyllosilicate nanoparticles in at least one solvent, (iii) contacting the solution (a) and the suspension (b), the non-swelling phyllosilicate nanoparticles having a thickness of 1 nm to 100 nm, and a larger dimension of 10 nm to 10 μm.

3. Method according to claim 2, which further comprises the following steps: Elimination of the solvent phase, Recovery of the nanoparticles.

4. Method according to claim 2, wherein the non-swelling phyllosilicates have one of the following chemical formulas:
(Si.sub.xGe(1−x)).sub.4M.sub.3O.sub.10(OH).sub.2,  (I) in which: x is a real number of the interval [0; 1], M denotes at least one divalent metal having the formula Mg.sub.y1Co.sub.y2Zn.sub.y3Cu.sub.y4Mn.sub.y5Fe.sub.y6Ni.sub.y7Cr.sub.y8; each index yi representing a real number of the interval [0; 1], and such that Σ.sub.i=1.sup.8yi=1, or
(Aly′M′(1−y′)).sub.2(Six′Ge(1−x′)).sub.2O.sub.5(OH).sub.4,  (II) in which: M′ denotes at least one trivalent metal chosen from the group consisting of gallium and rare earths, y′ is a real number of the interval [0; 1], x′ is a real number of the interval [0; 1], or
At(Six″Ge(1−x″)).sub.4M″.sub.kO.sub.10(OH).sub.2,  (III) in which: A denotes at least one monovalent cation of a metal element having the formula Li.sub.w1Na.sub.w2K.sub.w3Rb.sub.w4Cs.sub.w5, each wi representing a real number of the interval [0; 1] such that Σ.sub.i=1.sup.5wi=1, x″ is a real number of the interval [0; 1], M″ denotes at least one divalent metal having the formula Mg.sub.j1Co.sub.j2Zn.sub.j3Cu.sub.j4Mn.sub.j5Fe.sub.j6Ni.sub.j7Cr.sub.j8; each index ji representing a real number of the interval [0; 1], and such that Σ.sub.i=1.sup.8ji=1, k is a real number in the range [2.50; 2,85] t+2k is a real number of the interval [5.3; 6,0].

5. Method according to claim 2, in which the photoluminescent organic molecule is chosen from: Rhodamine B, or [9-(2-carboxyphenyl)-6-diethylamino-3-xanthenylidene]-dialylammonium chloride—or any other form of Rhodamine B such as for example Rhodamine B perchlorate, bromide of ethydium or bromide of 3,8-diamino-1-ethyl-6-phenylphenanthridinium, propidium iodide or di-iodide-iodide of 3,8-diamino-5-[3-(diethylmethylammonio)propyl]-6-phenylphenantridinium, the fluorescent brightener compound 220, the fluorescent brightener compound 251, the fluorescent brightener compound 351, the 1,1′-diethyl-2,2′-cyanine chloride, the 1,1′-diethyl-2,2′-dicarbocyanine iodide, mixtures of these compounds.

6. Hybrid nanoparticles composition comprising at least one non-swelling phyllosilicate and at least one molecule chosen from photoluminescent charged organic molecules, said organic molecule being adsorbed on the phyllosilicate, this composition being obtainable by the method according to claim 2.

7. Method according to claim 1, which further comprises the following steps: Elimination of the solvent phase, Recovery of the nanoparticles.

8. Method according to claim 7, wherein the non-swelling phyllosilicates have one of the following chemical formulas:
(Si.sub.xGe(1−x)).sub.4M.sub.3O.sub.10(OH).sub.2,  (I) in which: x is a real number of the interval [0; 1], M denotes at least one divalent metal having the formula Mg.sub.y1Co.sub.y2Zn.sub.y3Cu.sub.y4Mn.sub.y5Fe.sub.y6Ni.sub.y7Cr.sub.y8; each index yi representing a real number of the interval [0; 1], and such that Σ.sub.i=1.sup.8yi=1, or
(Aly′M′(1−y′)).sub.2(Six′Ge(1−x′)).sub.2O.sub.5(OH).sub.4,  (II) in which: M′ denotes at least one trivalent metal chosen from the group consisting of gallium and rare earths, y′ is a real number of the interval [0; 1], x′ is a real number of the interval [0; 1], or
At(Six″Ge(1−x″)).sub.4M″.sub.kO.sub.10(OH).sub.2,  (III) in which: A denotes at least one monovalent cation of a metal element having the formula Li.sub.w1Na.sub.w2K.sub.w3Rb.sub.w4Cs.sub.w5, each wi representing a real number of the interval [0; 1] such that Σ.sub.i=1.sup.5wi−1, x″ is a real number of the interval [0; 1], M″ denotes at least one divalent metal having the formula Mg.sub.j1Co.sub.j2Zn.sub.j3Cu.sub.j4Mn.sub.j5Fe.sub.j6Ni.sub.j7Cr.sub.j8; each index ji representing a real number of the interval [0; 1], and such that Σ.sub.i=1.sup.8ji=1, k is a real number in the range [2.50; 2,85] t+2k is a real number of the interval [5.3; 6,0].

9. Method according to claim 7, in which the photoluminescent organic molecule is chosen from: Rhodamine B, or [9-(2-carboxyphenyl)-6-diethylamino-3-xanthenylidene]-dialylammonium chloride—or any other form of Rhodamine B such as for example Rhodamine B perchlorate, bromide of ethydium or bromide of 3,8-diamino-1-ethyl-6-phenylphenanthridinium, propidium iodide or di-iodide-iodide of 3,8-diamino-5-[3-(diethylmethylammonio)propyl]-6-phenylphenantridinium, the fluorescent brightener compound 220, the fluorescent brightener compound 251, the fluorescent brightener compound 351, the 1,1′-diethyl-2,2′-cyanine chloride, the 1,1′-diethyl-2,2′-dicarbocyanine iodide, mixtures of these compounds.

10. Hybrid nanoparticles composition comprising at least one non-swelling phyllosilicate and at least one molecule chosen from photoluminescent charged organic molecules, said organic molecule being adsorbed on the phyllosilicate, this composition being obtainable by the method according to claim 7.

11. Method according to claim 1, wherein the non-swelling phyllosilicates have one of the following chemical formulas:
(Si.sub.xGe(1−x)).sub.4M.sub.3O.sub.10(OH).sub.2,  (I) in which: x is a real number of the interval [0; 1], M denotes at least one divalent metal having the formula Mg.sub.y1Co.sub.y2Zn.sub.y3Cu.sub.y4Mn.sub.y5Fe.sub.y6Ni.sub.y7Cr.sub.y8; each index yi representing a real number of the interval [0; 1], and such that Σ.sub.i=1.sup.8yi=1, or
(Aly′M′(1−y′)).sub.2(Six′Ge(1−x′)).sub.2O.sub.5(OH).sub.4,  (II) in which: M′ denotes at least one trivalent metal chosen from the group consisting of gallium and rare earths, y′ is a real number of the interval [0; 1], x′ is a real number of the interval [0; 1], or
At(Six″Ge(1−x″)).sub.4M″.sub.kO.sub.10(OH).sub.2,  (III) in which: A denotes at least one monovalent cation of a metal element having the formula Li.sub.w1Na.sub.w2K.sub.w3Rb.sub.w4Cs.sub.w5, each wi representing a real number of the interval [0; 1] such that Σ.sub.i=1.sup.5=1, x″ is a real number of the interval [0; 1], M″ denotes at least one divalent metal having the formula Mg.sub.j1Co.sub.j2Zn.sub.j3Cu.sub.j4Mn.sub.j5Fe.sub.j6Ni.sub.j7Cr.sub.j8; each index ji representing a real number of the interval [0; 1], and such that Σ.sub.i=1.sup.8ji=1, k is a real number in the range [2.50; 2.85] t+2k is a real number of the interval [5.3; 6.0].

12. Method according to claim 11, in which the non-swelling phyllosilicates are formed of a stack of elementary sheets: of 2:1 phyllosilicate type and of chemical formula Si.sub.4M.sub.3O.sub.10(OH).sub.2, more particularly of chemical formula Si.sub.4Mg.sub.3O.sub.10(OH).sub.2, or of 1:1 phyllosilicate type and of chemical formula Al.sub.2Si.sub.2O.sub.5(OH).sub.4, or of 2:1 phyllosilicate type and of chemical formula K Si.sub.4Mg.sub.2,5O.sub.10(OH).sub.2 (IIId) or K.sub.0,8Si.sub.4Mg.sub.2,6O.sub.10(OH).sub.2 (IIIf).

13. Method according to claim 12, in which the photoluminescent organic molecule is chosen from: Rhodamine B, or [9-(2-carboxyphenyl)-6-diethylamino-3-xanthenylidene]-dialylammonium chloride—or any other form of Rhodamine B such as for example Rhodamine B perchlorate, bromide of ethydium or bromide of 3,8-diamino-1-ethyl-6-phenylphenanthridinium, propidium iodide or di-iodide-iodide of 3,8-diamino-5-[3-(diethylmethylammonio)propyl]-6-phenylphenantridinium, the fluorescent brightener compound 220, the fluorescent brightener compound 251, the fluorescent brightener compound 351, the 1,1′-diethyl-2,2′-cyanine chloride, the 1,1′-diethyl-2,2′-dicarbocyanine iodide, mixtures of these compounds.

14. Method according to claim 11, in which the photoluminescent organic molecule is chosen from: Rhodamine B, or [9-(2-carboxyphenyl)-6-diethylamino-3-xanthenylidene]-dialylammonium chloride—or any other form of Rhodamine B such as for example Rhodamine B perchlorate, bromide of ethydium or bromide of 3,8-diamino-1-ethyl-6-phenylphenanthridinium, propidium iodide or di-iodide-iodide of 3,8-diamino-5-[3-(diethylmethylammonio)propyl]-6-phenylphenantridinium, the fluorescent brightener compound 220, the fluorescent brightener compound 251, the fluorescent brightener compound 351, the 1,1′-diethyl-2,2′-cyanine chloride, the 1,1′-diethyl-2,2′-dicarbocyanine iodide, mixtures of these compounds.

15. Method according to claim 1, in which the photoluminescent organic molecule is chosen from: Rhodamine B, or [9-(2-carboxyphenyl)-6-diethylamino-3-xanthenylidene]-dialylammonium chloride—or any other form of Rhodamine B such as for example Rhodamine B perchlorate, bromide of ethydium or bromide of 3,8-diamino-1-ethyl-6-phenylphenanthridinium, propidium iodide or di-iodide-iodide of 3,8-diamino-5-[3-(diethylmethylammonio)propyl]-6-phenylphenantridinium, the fluorescent brightener compound 220, the fluorescent brightener compound 251, the fluorescent brightener compound 351, the 1,1′-diethyl-2,2′-cyanine chloride, the 1,1′-diethyl-2,2′-dicarbocyanine iodide, mixtures of these compounds.

16. Hybrid nanoparticles composition comprising at least one non-swelling phyllosilicate and at least one molecule chosen from photoluminescent charged organic molecules, said organic molecule being adsorbed on the phyllosilicate, this composition being obtainable by the method according to claim 1.

17. Composition according to claim 16, wherein the ratio of photoluminescent organic molecule to phyllosilicate is from 0.001% of carbon to 10% of carbon, in terms of carbon mass relative to the phyllosilicate weight.

18. Composition according to claim 16, wherein the ratio of photoluminescent organic molecule to phyllosilicate is from 0.01% of carbon to 5% of carbon, in terms of carbon mass relative to the phyllosilicate weight.

19. A method for extracting from an environment a photoluminescent charged organic molecule, comprising applying an effective amount of non-swelling phyllosilicate nanoparticles, having a thickness of 1 nm to 100 nm, and a larger dimension of 10 nm to 10 μm, thereby forming a hybrid organic/inorganic composition by adsorption of said photoluminescent charged organic molecule to said non-swelling phyllosilicate nanoparticles, wherein when said environment is a biological tissue, the biological tissue is isolated or cultivated.

20. A method for neutralizing a photoluminescent charged organic molecule absorbed by an individual or by an animal, comprising causing said individual or animal to absorb non-swelling phyllosilicate nanoparticles, having a thickness of 1 nm to 100 nm, and a larger dimension of 10 nm to 10 μm, thereby forming a hybrid organic/inorganic composition by adsorption of said photoluminescent charged organic molecule to said non-swelling phyllosilicate nanoparticles.

Description

FIGURES

(1) FIG. 1 shows the X-ray diffractograms of a nanometric talc ( . . . ) and of a hybrid product prepared according to the protocol of Example 1, with two different amounts of Rhodamine B: - - - =0.6 mg Rhodamine B; solid line=12 mg of Rhodamine B. The intensity percentage (%) is plotted as ordinates as a function of distance, expressed in Angstrom, as abscissa.

(2) FIG. 2 shows the particle size of nanoscale talc (sample 1—.square-solid.) and those obtained after the addition of Rhodamine B in different amounts (sample 2—.box-tangle-solidup.: 0.6 mg RhB, sample 3—.circle-solid.: 12 mg RhB). The particle size (in nm) is given in ordinates according to the numbers of samples on the abscissa.

(3) FIG. 3 shows a schematic view of a device for implementing a method for preparing a synthetic phyllosilicate in which the solvothermal treatment is carried out continuously.

EXPERIMENTAL PART

(4) 1—Material and Methods

(5) 1.A. Equipment Rhodamine B: commercially available from Aldrich under the reference R6626-25G Natural Talc: it comes from the quarry of Trimouns, near Luzenac, in the Pyrenees Ariege (France). It was picked up manually, by on-site selection of the best possible quality of ore, from the point of view of the mineralogical purity 99% of talc). Synthetic nanoscale talc: it was manufactured according to the protocol described in Example 1 of application WO2013/004979. Nanoscale synthesis kaolinite:

(6) A solution of aluminum nitrate is prepared with 37.51 g (0.1 mole) of aluminum nitrate nonahydrate in 200 ml of pure water.

(7) A solution of potassium metasilicate is also prepared from 29.67 g of an aqueous solution of potassium metasilicate (K.sub.2SiO.sub.3) having a solids content of 52% (i.e. 0.1 mole of potassium metasilicate), of 100 ml of 1 M potassium hydroxide (KOH) and 200 mL of pure water.

(8) The first solution of aluminum nitrate is added with stirring to the potassium metasilicate solution and a white precipitate is formed instantly.

(9) The resulting suspension is stirred for 5 minutes. Three washing cycles are then carried out with distilled water and centrifugation at 8000 rpm for 10 minutes at each new centrifugation. These successive washes with elimination of the supernatant solution after each centrifugation make it possible to eliminate the potassium nitrate formed during the precipitation reaction of the precursor gel. The precursor gel placed in a closed titanium reactor placed in an oven is then subjected to a hydrothermal treatment at a temperature of 300° C. for 24 hours under the saturated vapor pressure of the water in the reactor. After cooling to room temperature, the reactor is opened and the suspension obtained is centrifuged. After centrifugation, a composition comprising particles of compound of formula Al.sub.2Si.sub.2O.sub.5(OH).sub.4 is recovered. The composition of particles recovered after centrifugation is dried in an oven (120° C., 12 hours) and then ground with mortar. The composition obtained is in the form of a white powder.

(10) The X-ray diffractogram of this composition has the following characteristic diffraction lines: a plane (001) located at a distance of 7.15 Å; a plane (020) located at a distance of 4.46 Å; a plane (110) located at a distance of 4.37 Å; a plane (111) located at a distance of 4.16 Å; a plane (021) located at a distance of 3.80 Å; a plane (002) located at a distance of 3.56 Å; a plane (130) and a plane (201) located at a distance of 2.56 Å; a plane (131) and a plane (200) located at a distance of 2.50 Å; a plane (202) and a plane (131) located at a distance of 2.33 Å; a plane (060), a plane (331) and a plane (331) located at a distance of 1.49 Å.

(11) The mid-infrared spectrum of the synthetic kaolinite composition obtained has four 3620 cm.sup.−1, 3651 cm.sup.−1, 3667 cm.sup.−1 and 3693 cm.sup.−1 vibration bands representative of the hydroxyl group elongation vibrations (—OH) synthetic kaolinite.

(12) Synthetic Nanoscale Mica:

(13) 300 ml of an aqueous solution of magnesium sulphate (33.27 g or 0.135 mol) and sulfuric acid (120 g of a 0.5 M solution) are prepared.

(14) A solution of potassium metasilicate is then prepared by diluting 59.35 g (i.e. 0.2 mol) of an aqueous solution of potassium metasilicate (K.sub.2SiO.sub.3) containing 52% solids in 150 ml of demineralized water. This solution of potassium metasilicate is added to the previous solution and a white precipitate is formed instantly.

(15) The resulting suspension is stirred for 5 minutes. Three washing cycles are then carried out with distilled water and centrifugation at 8000 rpm for 10 minutes at each new centrifugation. These successive washes with elimination of the supernatant solution ante after each centrifugation make it possible to eliminate the potassium sulphate formed during the precipitation reaction of the precursor gel. Finally, the recovered white precipitate is suspended in demineralized water to a final volume of 500 ml and subjected to ultrasound with magnetic stirring for 10 minutes until a homogeneous suspension of white color is obtained of precursor gel.

(16) 988 mg of hydrated potassium hydroxide (containing 85% of potassium hydroxide and 15% of water, i.e. 0.015 mole of added pure potassium hydroxide), previously diluted in 30 ml of demineralized water, are then added to the precursor gel, and the suspension obtained is stirred magnetically for 5 minutes at room temperature (22.5° C.).

(17) The precursor gel placed in a closed titanium reactor placed in an oven is then subjected to a hydrothermal treatment at a temperature of 300° C. for 24 hours under the saturated vapor pressure of the water in the reactor.

(18) After cooling to room temperature, the reactor is opened and the suspension obtained is centrifuged. After centrifugation, a composition comprising at least 80% by weight of particles of formula K.sub.0.3Si.sub.4Mg.sub.2.7O.sub.10(OH).sub.2 is recovered.

(19) The composition of particles recovered after centrifugation is dried in an oven for 12 hours at 120° C. and then ground in a mortar. The composition obtained is in the form of a white powder.

(20) The X-ray diffractogram of the composition of particles of formula K.sub.0.3Si.sub.4Mg.sub.2.7O.sub.10(OH).sub.2, thus obtained has the following characteristic diffraction lines: a plane (001) located at a distance of 10.15 Å; a plane (002) located at a distance of 5.03 Å; a plane (020) located at a distance of 4.53 Å; (003) and (022) planes located at a distance of 3.34 Å; a plane (131) located at a distance of 2.60 Å; a plane (005) located at a distance of 2.01 Å; a plane (060) located at a distance of 1.52 Å.

(21) The composition is then subjected to an anhydrous heat treatment at 550° C. in an oven for 5 hours. The composition obtained after the anhydrous heat treatment remains white.

(22) The X-ray diffractogram of the composition of particles of formula K.sub.0.3Si.sub.4Mg.sub.2.7O.sub.10(OH).sub.2 obtained after an anhydrous heat treatment at 550° C.; after the anhydrous heat treatment, the following characteristic diffraction lines: a plane (001) located at a distance of 10.24 Å; a plane (002) located at a distance of 5.02 Å; a plane (020) located at a distance of 4.56 Å; (003) and (022) planes located at a distance of 3.37 Å; a plane (131) located at a distance of 2.60 Å; a plane (005) located at a distance of 2.02 Å; a plane (060) located at a distance of 1.52 Å,

(23) I.B. Methods

(24) I.B.1. Syntheses

Example 1: Synthesis of the Hybrid Nanomaterial Composition Based on Synthetic Talc and Rhodamine B

(25) An aqueous solution of Rhodamine B dosed at 1 mg/ml is prepared. An aliquot of this solution (600 μl, i.e. 0.6 mg of Rhodamine B) is added at ambient temperature to a suspension of 1 g of nanotalc in 100 ml of pure water. The pink suspension is stirred under sonication for 5 min and then centrifuged at 14000 rpm for 20 min. It is noted that the supernatant is colorless which reflects the total adsorption of the photoluminescent compound on the mineral. The pellet consists of a pink paste having a strong photoluminescence under UV irradiation (365 nm). This paste can be dried in an oven (60° C. for 12 h) or by lyophylisation or any other drying technique.

Example 2: Synthesis of the Synthetic Kaolinite and Rhodamine b Hybrid Nanomaterial Composition

(26) The same protocol was applied as in Example 1, using the synthetic kaolinite whose preparation is detailed above.

Example 3: Synthesis of the Hybrid Nanomaterial Composition Based on Synthetic Mica and Rhodamine B

(27) The same protocol was applied as in Example 1, using the synthetic mica whose preparation is detailed above.

(28) I.B.2. Tests

(29) Characterization—Test No. 1: Adsorption Test:

(30) a) General Protocol

(31) In order to demonstrate the high adsorptivity of synthetic minerals and the way in which organic molecules interact with talc, various adsorption tests have been carried out. In a beaker, a mineral is mixed in the form of an aqueous suspension with a photoluminescent compound previously dissolved in water or a solvent. Water can be added to make the mixture sufficiently liquid. The whole is then stirred and passed under ultrasound until the mixture is homogeneous and without visible agglomerate. The final step is to centrifuge the mixture at 9000 rpm for about 20 minutes. At the end of this, the mineral is found plated in the bottom of the pot surmounted by the supernatant. As a result, if the mineral has fully adsorbed the photoluminescent compound, it is photoluminescent at the bottom of the pot and no photoluminescent molecule is detected in the supernatant. On the contrary, if it has not adsorbed the photoluminescent compound, the mineral retains its original color and the supernatant contains the photoluminescent molecule. If at the end of this first centrifugation the photoluminescent molecules are present both in the supernatant and in the mineral, this means that the mineral has not adsorbed the entire photoluminescent compound. The supernatant is then replaced by water in the pot for a second centrifugation. This operation makes it possible to see if the adsorption is strong or if the mineral rejects the photoluminescent material (leaching). This centrifugation step is performed as many times as necessary.

(32) b) Comparison Test of the Adsorbent Capacity of Natural and Synthetic Talc

(33) Firstly, adsorption tests were carried out to compare the adsorbent capacity of synthetic talc with that of natural talc with respect to Rhodamine B (pink, photoluminescent in the orange domain). The latter was brought into contact with synthetic talc or natural talc in the same ratio of “amount of photoluminescent compound/amount of mineral” for a better comparison of the results. At the end of the centrifugation, the photoluminescence of the minerals and the supernatant are compared in order to evaluate the adsorbent capacity of the mineral.

(34) Different tests having been carried out with uncharged dyes (β-carotene, curcumin, not reported here) have shown negative results in the adsorption test on synthetic talc.

(35) c) Lamellarity Influence Test on the Adsorption Capacity

(36) Various adsorption tests were performed to evaluate the role of mineral lamellarity in the adsorption of charged organic photoluminescent compounds. For this, we used different minerals with three-dimensional structure namely silica fume (3D structure), synthetic analcime (3D structure) and nanotalc (lamellar structure). At the end of the centrifugation, the color of the supernatants and minerals is compared to see if the structure adsorbs the photoluminescent compound. It should be noted that all the adsorption tests were carried out with Rhodamine B in the same ratio of “amount of photoluminescent compound/amount of mineral”, according to the protocol of Example 1, to better compare the results.

(37) Characterization—Tests No. 2: Characterization Methods

(38) a) X-Ray Diffraction

(39) The XRD analyzes were carried out on a device of the D2 Phaser type, from the Bruker company, with a wavelength of 1.54060 Å (λcu) over a diffraction angle range of from 0 to 80 °2θ. Moreover, the study of diffractograms made it possible to determine the coherence range of the mineral, i.e. the number of TOT sheets stacked along the c* axis without any major flaws. This coherence domain was calculated using Scherrer's formula:

(40) $L=\frac{0.91\times \lambda }{B\times \cos \left(\theta \right)}$
where L corresponds to the size of the coherent domain (Å), λ to the wavelength of the radiation, B to the width of the peak at half-height (rad) and θ the angle of the diffraction line.

(41) b) Granulometry

(42) The measurements of the particle size of the synthetic talc were carried out with a Vasco-2 granulometer of Cordouan Technologies, specific for the detection of nanoparticles. The analysis results correspond to a statistical study comprising 20 measurements with an acquisition time of one minute per measurement.

(43) I.B. Results

(44) I.B.1. Results of Adsorption Tests

(45) a) Adsorbent Capacity of Synthetic Talc

(46) The results of adsorption tests of natural talc and synthetic talc are as follows: In all cases, it was noted that after switching to the centrifuge, the mixture which was homogeneous and photoluminescent as a whole has two distinct phases: a photoluminescent talc precipitate at the bottom of the pot and a more or less photoluminescent supernatant. In the case of natural talc, the supernatant is in each case a little colored and photoluminescent, which means that the mineral has not completely adsorbed the photoluminescent compound. On the contrary, in the case of synthetic talc, the supernatant is in each case perfectly colorless and non-luminescent, which means that the mineral has completely adsorbed the photoluminescent compound.

(47) b) Role of Form Factor (Lamellarity) in Adsorption

(48) It has been found that a three-dimensional structure (analcime, silica fume) prevents the photoluminescent compound from adsorbing on the mineral. On the contrary, since it has a lamellar structure (nanotalc), the adsorption occurs.

(49) I.B.2. Characterization of the interaction “Synthetic Talc—Rhodamine B”

(50) a) XRD

(51) The XRD results (FIG. 1) show that the presence of Rhodamine B on the talc shifts the position of the line (001) towards the large angles.

(52) b) Granulometry

(53) The particle size results (FIG. 2) show that, in the presence of photoluminescent compounds, the size of the two populations of talc particles (natural, synthetic nanotalc) increases.