RU2491989C1 - Method of making mesoporous sorbent - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to methods of producing sorbents with a highly ordered MCM-41 type structure. Disclosed is a method of producing mesoporous materials with addition of quercetin and (+)-catechin during synthesis. The method involves preparing a reaction mixture based on Ludox-HS-40, CTABr, NaOH, H₂O, quercetin or (+)-catechin. The mixture is subjected to hydrothermal treatment, washed with distilled water and a mixture of 96% ethanol with ammonium nitrate, dried and calcined at 550°C.

EFFECT: invention enables to obtain MCM-41 type material which is efficient for sorption concentration of vitamins, which relate to a group of flavonoids, and as a carrier in chromatography.

9 ex, 3 dwg

Description

The invention relates to methods for producing silicate materials with a highly ordered structure, with a specific surface area of about 1000 m ² / g These materials can be used in heterogeneous catalysis, as well as carriers for chromatography.

The mesoporous material MCM-41 is known, which was first synthesized by Mobil employees (JS Beck, J.C. VartUli, WJ Roth, M.E. Leonowicz, C.T. Kresge, KD Schmitt, C.TW. Chu, t D. N. Olson, t E. W. Sheppard, S. B. McCullen, J. B. Higgins, and JL Schlenker A New Family of Mesoporous Molecular Sieves Prepared with Liquid Crystal Templates // J. Am. Chem. Sot . 1992, 114, 10834-10843.).

The synthesis of the mesoporous material type MCM-41 is carried out by liquid crystal transplantation by condensing the inorganic component in the presence of a surfactant used as a structuring agent, for example cetyltrimethylammonium bromide (CTABr) or hexadecyltrimethylammonium chloride (HTACl). As a source of silicon, Ludox-HS-40 and tetraethoxysilane (TEOS), sodium silicate, as well as silica gels and xerogels can be used.

A known method for producing mesoporous material MCM-41 (Xiu Mei TAI, Hong Xia WANG, Xiu Qi SHI A Novel Method for the Synthesis of Mesoporous Molecular Sieve MCM-41 / Chinese Chemical Letters Vol.16, No.6, 2005, p.843 -845), which includes obtaining the reaction medium from tetraethoxysilane, hexadecyltrimethylammonium bromide, distilled water (glycerol or glycol as solvent), ethylenediamine. The molar composition of the reaction mixture is 1TEOS: 0.7 CTABr: 130 solvent.

A known method of producing MCM-41 (RF patent 2287485, С01 В 33/20, 2006), which includes the production of alcohol-ammonia reaction mixture containing tetraethoxysilane, cetyltrimethylammonium bromide, ammonia, ethyl alcohol and water, further hydrothermal treatment at a temperature of 120 ° C during continuous rotation of the autoclave, characterized by a molar ratio of reactants in the synthesis of 1C ₈ H ₂₀ Si (TEOS): 0.2CTABr: 22NH ₃ : 50C ₂ H ₅ OH: 475H ₂ O.

Also known is a method for producing the mesoporous material MCM-41 (JP Da Silva, I. Ferreira Machado, JP Lourenc, LF Vieira Ferreira. Photochemistry of benzophenone adsorbed on MCM-41 surface. Microporous and Mesoporous Materials, 2005, 84, p. 1-10 R. Ryoo, JM Kim. Structural Order in MCM-41 controlled by Shifting Silicate Polymerization Equilibrium / J. Chem. Soc., Chem. Commun. L995, p. 711-712), selected as a prototype. The method by which this sorbent is prepared includes the preparation of materials from a reaction medium which includes: Ludox HS-40, 1M NaOH solution, hexadecyltrimethylammonium chloride (HTACl) (molar composition of the resulting mixture 4SiO: Na ₂ O: HTACl: 400H ₂ O). In this case, Ludox HS-40 is mixed with a 1M NaOH solution at a temperature of 75 ° C for 1 hour. Then, after cooling to room temperature, this solution was slowly added with stirring with a magnetic stirrer to a mixture of HTACl and water. After that, the resulting product is placed in a propylene container and at a temperature of 100 ° C for 24 hours. After this time, the pH is checked and, if necessary, adjusted to 10 with acetic acid. The mixture is kept at 100 ° C for 24 hours, sodium chloride is added and the mixture is left at 100 ° C for 10 days. The product is then centrifuged, washed with water and dried at 80 ° C. Then the remaining template is extracted with a mixture of 96% ethanol and ammonium nitrate at a boiling point for 2 hours. Next, the product is calcined at a temperature at 550 ° C for 10 hours

The disadvantage of this method for the synthesis of mesoporous material is the chemical conversion of substances after sorption, leading to a change in the antioxidant ability of flavonoids due to the high catalytic activity of the material.

A known method for producing the mesoporous material MCM-41 (R. Ryoo, CH Kohhd In-Soo Park. Synthesis of highly ordered MCM-41 by micelle-packing control with mixed surfactants / Chem. Commun., 1999, p.1413-1414. Xiu S. Zhao, GQ (Max) Lu, Graeme J. Millar Advances in Mesoporous Molecular Sieve MCM-41 / Ind. Eng. Chem. Res. 1996, 35), which includes preparing the reaction mixture from a solution of sodium silicate or Ludox -HS-40, 1M solution of NaOH, hexadecyltrimethylammonium chloride (HTACl), distilled water, ammonia. This mixture was placed in a propylene container and kept at a temperature of 100 ° C for 24 hours. Then the mixture is cooled to room temperature and the pH is checked; if necessary, acetic acid is added to pH = 10. This procedure is repeated for another 2 days. Then the product is washed with distilled water, dried at 97 ° C, then washed with a mixture of 96% ethanol, hydrochloric acid and water and calcined in air at 550 ° C for 2 hours.

The disadvantage of the sorbent obtained by the above method is the chemical conversion of the separated substances after sorption due to the high catalytic activity of the material, which can lead to a change in the antioxidant ability of flavonoids.

The objective of the invention is to develop a method for producing a sorbent type MCM-41 for the sorption concentration of quercetin and (+) - catechin.

The technical result consists in obtaining a mesoporous material of the MCM-41 type, which has sorption ability with respect to flavonoids and does not lead to chemical transformations of quercetin and (+) - catechin during their sorption separation and concentration.

The technical result is achieved by the fact that to obtain a mesoporous sorbent, a reaction mixture is prepared from Ludox HS-40, 1M NaOH, CTABr, distilled water, and a solution of quercetin (or (+) catechin). Further hydrothermal treatment, washing the product with distilled water, drying, extracting the remaining template with 0.1 M solution of ammonium nitrate in 96% ethanol (product-extractant ratio 1:20) or a mixture of 96% ethanol, hydrochloric acid, distilled water (volume ratio of components 230: 1: 7.5) with a product-extractant ratio of 1:20, drying and calcining the sample at 550 ° C for two hours.

Ludox HS-40 - silica gel 40% (mass.) Concentration, particle size 12 nm, molar ratio SiO ₂ / Na ₂ O 95: 1, manufacturer DuPont.

The surface and bulk properties of mesoporous materials were studied according to isotherms of low-temperature nitrogen adsorption / desorption (BET isotherms), X-ray diffraction analysis, and RG spectroscopy. Nitrogen adsorption and desorption isotherms were recorded on a Tristar II 3020 specific area analyzer. Radiographs were taken on an ARL ORGM'X X-ray spectrometer using CuK α radiation in the range 2Θ - 2.00-10.00 °. The IR spectra of the samples were recorded using a Bruker Equinox 55 IR spectrometer with Fourier transform in diffuse reflection mode (DRIFT). Each spectrum was recorded in the range of wave numbers 400-4000 cm ^-1 with a resolution of 4 cm ^-1 . To remove adsorbed water, as well as to establish structural changes in the sample, the Harricks cell prefix for in situ heating was used. Nitrogen was passed through the sample at a rate of about 60 ml / min, which made it possible to remove desorption and decomposition products from the prefix when the sample was heated. IR spectra were recorded after thermostating of the samples at 30 and 250 ° C. As a control sample, an MCM-41 sorbent was synthesized without the addition of flavonoids.

Figure 1 presents table 1 containing the characteristics of the obtained samples

1 - sorbent without the addition of flavonoids

2 - sorbent with the addition of (+) - catechin (example 4)

3 - sorbent with the addition of (+) - catechin (example 3)

4 - sorbent with the addition of quercetin (example 1)

5 - sorbent with the addition of quercetin (example 2));

figure 2 presents table 2 containing the characteristics of the obtained samples

1 - sorbent without the addition of flavonoids

2 - sorbent with the addition of (+) - catechin (example 7)

3 - sorbent with the addition of (+) - catechin (example 8)

4 - sorbent with the addition of quercetin (example 5)

5 - sorbent with the addition of quercetin (example 6));

figure 3 presents the output sorption curves of quercetin and (+) - catechin on a sorbent with the addition of quercetin (example 1)

1 - (+) - catechin

2 - quercetin

Examples illustrating the invention:

Example 1

A method of obtaining a mesoporous material MCM-41 with molecular prints of quercetin. The method includes obtaining a reaction mixture from Ludox HS-40, 1M NaOH, CTABr, distilled water, and a solution of quercetin. For this, it is necessary to obtain the following solutions:

Solution A:

8.7 g of Ludox HS-40 are mixed with 28.9 g of 1 M NaOH solution. This solution is maintained at a temperature of 75 ° C for 1 hour. In this case, mixing is necessary to obtain a homogeneous solution.

Solution B:

19.2 g of hexadecyltrimethylammonium bromide (CTABr) are mixed with 49.6 g of distilled water.

Solution C:

0.003 g of quercetin in 10 g of distilled water.

Then, solution A is added to solution B with constant stirring (using a magnetic stirrer) (the rate of addition of solution A is 2 ml / min). After which solution C is added (the rate of addition of solution C is 2 ml / min), stirring continues for one hour after adding the last portion of solution C.

This reaction mixture is transferred to a propylene tank. The container is placed in an autoclave and maintained at a temperature of 100 ° C for 24 hours under static conditions. Then the pH is controlled (pH should be 10). The pH is adjusted by the addition of concentrated acetic acid. After 24 hours, 2.6 g of NaCl was added, after which the reaction mixture was kept at 100 ° C for another 8 days.

Subsequently, the template (CTABr) as well as the polyphenols are removed with distilled water (800 cm ³ ). Then the product is dried at a temperature of 60-80 ° C and is extracted with 0.1 M solution of NH ₄ NO ₃ in 96% ethanol (200 cm ³ ). Next, the dry residue is calcined at a temperature of 550 ° C for 2 hours

Surface and bulk characteristics of the obtained sample are shown in table 1.

Example 2

A method of producing a mesoporous material MCM-41 with molecular imprints of quercetin, which differs from the previous one in that a solution of C: 0.03 g of quercetin in 10 g of distilled water. For this, it is necessary to obtain the following solutions:

Solution A:

8.7 g of Ludox HS-40 are mixed with 28.9 g of a 1M NaOH solution.

Solution B:

19.2 g of hexadecyltrimethylammonium bromide (CTABr) are mixed with 49.6 g of distilled water.

Solution C:

0.03 g of quercetin in 10 g of distilled water.

Surface and bulk characteristics of the obtained sample are shown in table 1.

Example 3

A method of producing a mesoporous material MCM-41 with molecular imprints of (+) - catechin, different from the previous one in that a solution of C: 0.003 g (+) - catechin in 10 g of distilled water. For this, it is necessary to obtain the following solutions:

Solution A:

8.7 g of Ludox HS-40 are mixed with 28.9 g of a 1M NaOH solution.

Solution B:

19.2 g of hexadecyltrimethylammonium bromide (CTABr) are mixed with 49.6 g of distilled water.

Solution C:

0.003 g (+) - catechin in 10 g of distilled water.

Surface and bulk characteristics of the obtained sample are shown in table 1.

Example 4

A method of producing a mesoporous material MCM-41 with molecular imprints of (+) - catechin, different from the previous one in that a solution of C: 0.03 g (+) - catechin in 10 g of distilled water.

For this, it is necessary to obtain the following solutions:

Solution A:

8.7 g of Ludox HS-40 are mixed with 28.9 g of 1 M NaOH solution.

Solution B:

19.2 g of hexadecyltrimethylammonium bromide (CTABr) is mixed with 49.6 g of distilled water.

Solution C:

0.03 g (+) - catechin in 10 g of distilled water.

Surface and bulk characteristics of the obtained sample are shown in table 1.

Example 5

A method of obtaining a mesoporous material MCM-41 with molecular prints of quercetin. The method includes obtaining a reaction mixture from Ludox HS-40, 1M NaOH, CTABr, ammonia, distilled water, and a solution of quercetin. For this, it is necessary to obtain the following solutions:

Solution A:

26.3 g of Ludox HS-40 are mixed with 40 g of 1 M NaOH solution. This solution is aged at 60 ° C for 1 hour.

Solution B:

16.6 g of hexadecyltrimethylammonium bromide (CTABr) is mixed with 39.5 g of distilled water and 0.3 g of NH ₄ OH (25%)

Solution C:

0.003 g of quercetin in 10 g of distilled water.

Then, solution A is added to solution B with constant stirring (using a magnetic stirrer). The rate of addition of solution A is 2 ml / min. After which solution C is added, stirring continues for an hour after adding the last portion of solution C.

This reaction mixture is placed in a propylene tank, which is placed in an autoclave and maintained at a temperature of 100 ° C for 24 hours under static conditions. Then the pH is controlled (pH should be 10). The pH is adjusted by the addition of concentrated acetic acid. pH is checked 3 days in a row. The reaction mixture is aged at 100 ° C for 6 days.

Subsequently, the template (CTABr) as well as the polyphenolic compounds are removed with distilled water (800 cm ³ ) and then extracted with a mixture of C ₂ H ₅ OH-HCl-H ₂ O (volume ratio of components 230: 1: 7.5) in a ratio of 1 :twenty. The residue is dried at a temperature of 60-80 ° C and calcined at a temperature of 550 ° C for 2 hours.

Surface and bulk characteristics of the obtained sample are shown in table 2.

Example 6

A method of producing a mesoporous material MCM-41 with molecular imprints of quercetin, different from the previous one in that a solution of C: 0.03 g of quercetin in 10 g of distilled water. For this, it is necessary to obtain the following solutions:

Solution A:

26.3 g of Ludox HS-40 are mixed with 40 g of a 1M NaOH solution.

Solution B:

16.6 g of hexadecyltrimethylammonium bromide (CTABr) is mixed with 39.5 g of distilled water and 0.3 g of NH ₄ OH (25%)

Solution C:

0.03 g of quercetin in 10 g of distilled water.

Surface and bulk characteristics of the obtained sample are shown in table 2.

Example 7

A method of producing a mesoporous material MCM-41 with molecular imprints of (+) - catechin, different from the previous one in that a solution of C: 0.003 g of (+) - catechin in 10 g of distilled water. For this, it is necessary to obtain the following solutions:

Solution A:

26.3 g of Ludox HS-40 are mixed with 40 g of a 1M NaOH solution.

Solution B:

16.6 g of hexadecyltrimethylammonium bromide (CTABr) is mixed with 39.5 g of distilled water and 0.3 g of NH ₄ OH (25%)

Solution C:

0.003 g (+) - catechin in 10 g of distilled water.

Surface and bulk characteristics of the obtained sample are shown in table 2.

Example 8

A method of producing a mesoporous material MCM-41 with molecular imprints of (+) - catechin, different from the previous one in that the solution C: 0.03 g of (+) - catechin is mixed with 10 g of distilled water. For this, it is necessary to obtain the following solutions:

Solution A:

26.3 g of Ludox HS-40 are mixed with 40 g. 1M NaOH solution.

Solution B:

16.6 g of hexadecyltrimethylammonium bromide (CTABr) is mixed with 39.5 g of distilled water and 0.3 g of NH ₄ OH (25%)

Solution C:

0.03 g (+) - catechin in 10 g of distilled water.

Surface and bulk characteristics of the obtained sample are shown in table 2.

The sorption ability of the obtained sorbent with respect to certain flavonoids can be considered by the example of the separation of quercetin and (+) - catechin.

Example 9

A sorbent weighing 0.35 g was placed in a solid phase extraction cartridge. Then, the initial model acetonitrile solutions of (+) - catechin or quercetin with the addition of 1% NH ₄ OH were passed. The residual concentration of (+) catechin and quercetin in solution was determined by UV spectrophotometry. The output sorption curves of quercetin and (+) - catechin are shown in Fig. 3.

Claims (1)

A method of producing a mesoporous sorbent, including the preparation of a reaction mixture based on Ludox-HS-40, hexadecyltrimethylammonium bromide (CTABr), NaOH, distilled water, quercetin or (+) catechin, hydrothermal treatment, washing with distilled water, drying, extraction with 0.1 M solution ammonium nitrate in 96% ethanol with a product / extractant ratio of 1:20 or a mixture of 96% ethanol, hydrochloric acid, distilled water with a volume ratio of components of 230: 1: 7.5 and a product / extractant ratio of 1:20, drying and calcination When T = 550 ° C for 2 hours, the reaction mixture has a molar ratio: (0,9-1,1) SiO _2: (0,9-1,1) Na ₂ O: (0,9-1 , 1) CTABr: (90-110) H ₂ O: (0.00009-0.00011) quercetin or (0.9-1, l) SiO ₂ : (0.9-1.1) Na ₂ O: (0.9-1.1) CTABr: (90-110) H ₂ O: (0.000009-0.000011) quercetin or (0.9-1.1) SiO ₂ : (0.9-1, 1) Na ₂ O: (0.9-1.1) CTABr: (90.0-110) H ₂ O: (0.00009-0.00011) (+) - catechin or (0.9-1, 1) SiO ₂ : (0.9-1.1) Na ₂ O: (0.9-1.1) CTABr (90-110) H ₂ O: (0.000009-0.000011) (+) - catechin.

Images