A composite pervaporation membrane and its preparation method and application

Abstract

The present invention belongs to the field of pervaporation membrane separation technology, and specifically relates to a composite pervaporation membrane. A composite pervaporation membrane, the composite pervaporation membrane is composed of a porous support membrane and a continuous membrane layer located thereon, wherein the continuous membrane layer is composited by a polyhydroxy macrocyclic compound and a rubber polymer, and the polyhydroxy macrocyclic compound and the rubber polymer molecules are connected by weak hydrogen bonds between the two material molecules, thereby forming an interconducting network structure. The present invention uses polyhydroxy macrocyclic compounds, which have large hydrophobic cavities and abundant hydroxyl groups. The polyhydroxy macrocyclic compounds can form hydrogen bond interactions with fragrance components, reducing the mass transfer resistance of the fragrance components through the membrane, facilitating the preferential permeation of the fragrance components through the membrane, and enhancing the membrane's selective separation performance for the fragrance components.

Description

Technical Field

[0001] The invention belongs to the technical field of pervaporation membrane separation, and in particular relates to a composite pervaporation membrane. Background Art

[0002] Flavors and fragrances are important additives in cigarette production. Unflavored cigarettes have a bitter taste, but the addition of flavors can significantly improve the smell and taste of cigarettes, resulting in a pleasant smoking quality. They also impart a distinctive aroma, making them a selling point for tobacco brands. Most cigarette products primarily emphasize the natural, mellow aroma of tobacco. Tobacco contains thousands of compounds, many of which are naturally aromatic. Therefore, tobacco flavors and fragrances extracted from tobacco as additives offer a pure, non-toxic aroma. Furthermore, tobacco flavors have a wide range of other uses. For example, 2-phenylethanol is not only used as a flavoring but can also be used to produce the high-value flavoring compound phenylethyl acetate. β-ionone, for example, can be used in soap flavorings and is also a raw material for the synthesis of vitamin A. Therefore, extracting flavoring compounds from tobacco has become a research goal for many researchers.

[0003] Currently, tobacco flavors are mostly extracted using simultaneous distillation and solvent extraction. Xu Chunping et al. (Journal of Light Industry, 2018, 33(05): 37-43) prepared tobacco bud flavors using enzymatic hydrolysis and the Maillard reaction, and purified the flavors using distillation and extraction. This method successfully extracted and separated key tobacco flavoring substances, including myristic acid, dihydroactin, caryophyllene oxide, nicotinene, phyton, damasconone, megastigmatrienone, oleamide, and 2-n-pentylfuran, from tobacco buds. However, the extraction process is complex, time-consuming, and costly. Chu Guohai et al. (Fragrances and Fragrances Cosmetics, 2006(01):17-21) used ultrasonic solvent extraction technology to extract aroma components from tobacco. This method successfully separated 112 aroma components from tobacco. Although the content of hydrocarbons and acids was high, their aroma intensity was not high. However, the content of aldehydes (furfural, benzaldehyde, etc.) and ketones (β-damascenone, dihydrodamascenone, etc.) with strong aroma intensity and great contribution to tobacco aroma was low. Therefore, this solvent extraction method has poor selectivity for the separation of aldehydes and ketones with strong aroma. Qin Yongcun et al. (Anhui Agricultural Science, 2016, 44(22): 107-110) used static microwave vacuum drying technology to prepare endogenous solid tobacco flavors; static microwave vacuum drying technology can remove the highest amount of nicotine, and the content of tobacco flavor components such as β-damascenone, furfural, megastigmatrienone, solanone benzaldehyde, phenylacetaldehyde and furfuryl alcohol after microwave vacuum drying is higher than that of samples after conventional spray drying and freeze drying; this method has low energy consumption and short time consumption, but for some flavor components in tobacco, there is a phenomenon of volatilization or reaction at high temperature, resulting in the loss of some flavor components.

[0004] The separation and extraction of flavor components in tobacco are complex and difficult to separate. Although membrane separation technology has the characteristics of high efficiency, environmental protection, and low energy consumption and is applied to various fields such as gas and liquid separation, the use of membrane separation technology for the separation and extraction of flavor components in tobacco is still rare. Wang Haoya et al. (Chinese Tobacco Science, 2021, 42(06): 86-91) used aquaporin hollow fiber forward osmosis membrane as a separation membrane and a saturated NaCl aqueous solution as an extractant to extract and separate the flavor components of Honghua Dajinyuan tobacco leaves. Compared with evaporation concentration, the types of flavoring substances in the extract obtained by forward osmosis concentration are the same, but the total amount is nearly doubled, among which the content of β-ionone, dihydroactin and linalool increases most significantly. The product obtained by this method is of good quality and has little flavor loss, but the extractant NaCl needs to be replaced frequently, and the extract will contain a large amount of Cl — , which affects the quality of the product to a certain extent. Zheng Jianyu et al. (Tobacco Science and Technology, 2019, 52(12): 70-78) used ultrafiltration membranes with different pore sizes to separate the components of tobacco leaf extracts. The results showed that the molecules retained by 10, 2 and 1 kDa membranes were mostly large molecules such as proteins and polysaccharides, while the types and contents of volatile aroma components were low, and their contribution to the aroma characteristics of the product was small. However, the small molecule alcohols, ketones, esters and heterocyclic components in tobacco leaves that play an important role in the aroma of the product are all enriched in the filtrate of the 300Da membrane. Therefore, the use of ultrafiltration membranes with different pore sizes can regulate different types of components in tobacco leaves, thereby achieving the enrichment of flavor components. This method relies on the pore size of the ultrafiltration membrane for separation operations, and the total amount of the product obtained is large, but the product composition is complex, and it does not have the effect of selective separation for specific flavor components. Yokoi (Journal of Chromatographic Science, 2017, 55(3): 373-377) used low-density polyethylene membranes to extract volatile flavor compounds from tobacco leaves, followed by ether extraction and analysis. The results showed that membrane extraction recovered a large amount of aromatic alcohols, such as benzyl alcohol, phenylethyl alcohol, and β-damascenone. However, the slow mass transfer and low extraction efficiency restricted the development of this method.

[0005] Scientists have already focused on and initially applied membrane separation methods to extract tobacco flavors, but current results remain limited. Potential challenges include slow mass transfer rates, poor selectivity, reliance on membrane pore size, the use of organic solvents, which can be environmentally polluting, and high separation costs. Pervaporation membrane separation technology, which has rapidly developed in recent years due to its high efficiency, cost-effectiveness, safety, and environmental friendliness, is considered an excellent separation technology. Therefore, using pervaporation membrane separation technology for separating flavor components in tobacco holds considerable promise. Summary of the Invention

[0006] The present invention provides a composite pervaporation membrane, which is mainly used for separating and extracting aroma components, especially for separating, extracting and recovering aroma components in tobacco.

[0007] The composite pervaporation membrane provided by the present invention comprises a polyhydroxy macrocyclic compound in one portion and a rubbery polymer in the other. The rubbery polymer possesses advantages such as good organic affinity, hydrophobicity, large free volume, excellent film-forming ability, and thermal stability, making it an ideal polymer material for separating flavor components from tobacco. The polyhydroxy macrocyclic compound has large hydrophobic cavities and abundant hydroxyl groups, which can form hydrogen bonds with alcohol components in tobacco, enhancing the adsorption and solubility of alcohol flavors on the membrane surface, reducing the mass transfer resistance of flavor components through the membrane, and facilitating the preferential permeation of flavor components through the membrane, thereby enhancing the membrane's selective separation performance for flavor components. The pervaporation membrane prepared by the present invention can be used to extract flavor components from tobacco, as well as to separate and extract other aroma components.

[0008] The technical solutions of the present invention are as follows:

[0009] A composite pervaporation membrane consists of a porous support membrane and a continuous membrane layer located thereon, wherein the continuous membrane layer is composited by a polyhydroxy macrocyclic compound and a rubber polymer. The polyhydroxy macrocyclic compound and the rubber polymer molecules are connected by weak hydrogen bonds between the two material molecules, thereby forming an interconducting network structure.

[0010] Furthermore, the polyhydroxy macrocyclic compound is a macrocyclic compound having a "cylindrical" annular macropore and the surface of the cyclic molecule is rich in multiple hydroxyl groups.

[0011] Preferably, the polyhydroxy macrocyclic compound is prepared by one of the following methods:

[0012] Polyhydroxy macrocyclic compound 1: adding cyclodextrin to a solution containing a metal ion compound having a mass fraction of 0.5 to 15 wt% and mixing evenly, wherein the mass fraction of cyclodextrin in the mixed solution is 1 to 10 wt%; placing the mixed solution in a methanol protective atmosphere at 15 to 60° C. and growing for 1 to 21 days; collecting a crude product; washing and drying to obtain the polyhydroxy macrocyclic compound 1, wherein the metal ion-containing compound is any one of potassium nitrate, potassium hydroxide, and potassium benzoate;

[0013] Polyhydroxy macrocyclic compound II: p-tert-butylphenol, a 37% formaldehyde aqueous solution, and a 5-20% sodium hydroxide aqueous solution are added simultaneously to a three-necked flask, and the mixture is reacted at a temperature of 25-80° C. for 3-12 hours using a microwave-assisted stirrer under nitrogen protection. Water is removed during the reaction. After the reaction is completed, dehydration is performed by rotary evaporation to obtain a brown viscous substance, which is a crude product of the polyhydroxy macrocyclic compound II. The crude product is washed with ethyl acetate and hydrochloric acid until neutral, and then dried to obtain the polyhydroxy macrocyclic compound II.

[0014] The molar ratio of p-tert-butylphenol to formaldehyde is 1:1-5; the ratio of the mass of sodium hydroxide to the total mass of p-tert-butylphenol and formaldehyde is (0.5-5):100;

[0015] Preferably, the rubbery polymer is prepared by the following method:

[0016] Monomer 1, monomer 2, and catalyst 1 are sequentially added to a three-necked flask, stirred and mixed to allow a chemical reaction to occur, wherein the chemical reaction is carried out using ultrasonic chemical synthesis under a nitrogen atmosphere, and the reaction is terminated when the solution becomes viscous; after the reaction is completed, the mixture is sequentially washed with deionized water and a 2% sodium bicarbonate solution until neutral to obtain a crude rubber polymer product; a crosslinking agent is added to the crude product, and the mixture is thoroughly stirred until uniformly mixed to obtain the rubber polymer;

[0017] The chemical synthesis reaction is carried out in a nitrogen protective atmosphere by ultrasonic chemical synthesis at a temperature range of 50 to 90° C. for 4 to 24 hours; the monomer one is an anhydrous material, and the material type is any one of hexamethylcyclotrisiloxane, hexaethylcyclotrisiloxane, octamethylcyclotetrasiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane and decamethylcyclopentasiloxane; the monomer two is any one of divinyltetramethyldisiloxane, 1,1,3,3-tetramethyldisiloxane, hexamethyldisiloxane and decamethyltetrasiloxane; the catalyst one is any one of potassium hydroxide silanol, sodium hydroxide silanol and (tetramethylammonium hydroxide) silicon alkoxide; the molar ratio of the monomer one to the monomer two is (5 to 10):1; and the mass of the catalyst one is 1 to 5% of the total mass of the monomer one and the monomer two;

[0018] The crosslinking agent is any one of tetraethoxysilane, p-tolyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane and vinyltriethoxysilane; the mass ratio of the crosslinking agent to the crude product is (1-10): (50-70).

[0019] Preferably, the composite pervaporation membrane is prepared by the following method:

[0020] A polyhydroxy macrocyclic compound is dispersed in a solvent to prepare a uniform solution A with a mass fraction of 1 to 25 wt %; a rubbery polymer is dispersed in the same solvent to prepare a uniform solution B with a mass fraction of 5 to 50 wt %; the polyhydroxy macrocyclic compound solution A is gradually added with the rubbery polymer solution B under microwave-assisted mechanochemical action, with the volume ratio of solution B to solution A being 1:(0.1 to 5); after being uniformly stirred, a second catalyst is added while continuing to stir until the solution becomes viscous, which is a casting solution C, with the mass ratio of the second catalyst to the polyhydroxy macrocyclic compound being (1 to 30):100; the casting solution C is coated on the surface of a porous support membrane, first naturally dried at room temperature until a wet membrane is formed, and then thermally cross-linked at a temperature range of 30 to 90° C. until the solvent is completely volatilized, thereby preparing the pervaporation membrane for extracting flavor components from tobacco.

[0021] The solvent is any one of n-heptane, n-hexane, benzene, toluene, dimethyl ether and carbon tetrachloride; and the catalyst 2 is any one of dibutyltin dilaurate, stannous isooctanoate and zinc isooctanoate.

[0022] Another object of the present invention is to provide the use of the above-mentioned pervaporation membrane in separating, extracting and recovering flavor components in tobacco.

[0023] A method for separating flavor components from tobacco, comprising passing a tobacco extract to be extracted through the pervaporation membrane according to any one of claims 1 to 5, wherein the tobacco extract has a temperature of 40 to 90° C. and a flow rate of 10 to 200 L / h.

[0024] Beneficial effects of the present invention:

[0025] The present invention uses polyhydroxy macrocyclic compounds. Polyhydroxy macrocyclic compounds have large hydrophobic cavities and abundant hydroxyl groups, which can form hydrogen bond interactions with flavor components, reducing the mass transfer resistance of the flavor components through the membrane, facilitating the preferential permeation of the flavor components through the membrane, and enhancing the membrane's selective separation performance for the flavor components. The prepared pervaporation membrane is used for the pervaporation separation of flavor components in tobacco. The results show that polyhydroxy macrocyclic compounds have excellent permeation flux and separation factors for flavor components when applied to pervaporation separation membranes. Rubbery polymers have excellent organic affinity, thermal stability, and chemical inertness. The pervaporation membrane prepared with rubbery polymers as the polymer matrix has excellent physical and chemical stability and is excellent in the separation and extraction of alcohol components. The preparation process of the pervaporation membrane for extracting flavor components from tobacco according to the present invention is simple, low in preparation cost, and has low environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic structural diagram of a composite pervaporation membrane comprising a polyhydroxy macrocyclic compound provided by the present invention. DETAILED DESCRIPTION

[0027] The following non-limiting examples may enable those skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0028] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents and materials described are all commercially available unless otherwise specified.

[0029] One of the specific implementation methods:

[0030] In its first aspect, the present invention discloses a pervaporation membrane for extracting tobacco flavor components and its preparation method. The membrane consists of two components: a polyhydroxy macrocyclic compound is surface-modified and then organically fused into a uniform casting solution under microwave-assisted mechanochemical action. This membrane is then prepared by surface coating. The membrane retains the polyhydroxy macrocyclic compound's affinity for flavor components and superhydrophobicity while also maintaining the high hydrophobicity, large free volume, and strong chain migration capability of the rubbery polymer.

[0031] The polyhydroxy macrocyclic compound is either one of polyhydroxy macrocyclic compound 1 and polyhydroxy macrocyclic compound 2, and the preparation methods thereof are as follows:

[0032] Preparation method of polyhydroxy macrocyclic compound 1:

[0033] The method comprises the following steps: adding component A containing a coordination center metal ion to deionized water, stirring at room temperature until completely dissolved, ensuring that the mass fraction of component A containing a coordination center metal ion in the aqueous solution is 0.5 to 15 wt%, and preparing solution B; adding cyclodextrin to solution B, mechanically stirring until the mixture is uniform, and then preparing solution C, ensuring that the mass fraction of cyclodextrin in the solution is 1 to 10 wt%; placing solution C in a methanol protective atmosphere for growth for 1 to 21 days; collecting a crude product, washing it with methanol 3 to 5 times to remove crystal water; and drying the obtained product under vacuum at 20 to 80° C. for 12 to 36 hours to obtain a dry polyhydroxy macrocyclic compound.

[0034] The type of component A containing the coordination center metal ion is any one of potassium nitrate, potassium hydroxide and potassium benzoate; the temperature range required for the growth of solution C under a methanol protective atmosphere is 15 to 60°C;

[0035] Preparation method of polyhydroxy macrocyclic compound II:

[0036] Add 4-tert-butylphenol, formaldehyde aqueous solution, and sodium hydroxide aqueous solution into a three-necked flask at once, and react at a temperature of 25-80° C. for 3-12 hours using a microwave-assisted stirrer under nitrogen protection. During the reaction, a water separator is used to remove water. After the reaction is completed, rotary evaporation is used to dehydrate to obtain a brown viscous substance, which is a crude product of the polyhydroxy macrocyclic compound II. The crude product is washed with ethyl acetate and hydrochloric acid until neutral and then dried to obtain the polyhydroxy macrocyclic compound II.

[0037] The mass concentration of the formaldehyde aqueous solution is 37%; the molar ratio of p-tert-butylphenol to formaldehyde is 1:(1-5); the mass concentration of the sodium hydroxide aqueous solution is (5-20)%; the mass ratio of sodium hydroxide to the total mass of p-tert-butylphenol and formaldehyde is (0.5-5):100;

[0038] The rubbery polymer preparation method comprises the following steps: adding monomer 1, monomer 2, and catalyst 1 sequentially into a three-necked flask, mechanically stirring and mixing to allow a chemical reaction to occur, wherein the chemical reaction is carried out using an ultrasonic chemical synthesis method under a nitrogen atmosphere, and the reaction is terminated when the solution becomes viscous; after the reaction is completed, washing the solution with deionized water and a 2% sodium bicarbonate solution sequentially until the solution is neutral to obtain a crude rubbery polymer product; adding a crosslinking agent to the crude product, and stirring the mixture thoroughly until the mixture is uniformly mixed to obtain the rubbery polymer;

[0039] The chemical synthesis reaction is carried out in a nitrogen protective atmosphere by ultrasonic chemical synthesis at a temperature range of 50 to 90° C. for 4 to 24 hours; the monomer one is an anhydrous material, and the material type is any one of hexamethylcyclotrisiloxane, hexaethylcyclotrisiloxane, octamethylcyclotetrasiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane and decamethylcyclopentasiloxane; the monomer two is any one of divinyltetramethyldisiloxane, 1,1,3,3-tetramethyldisiloxane, hexamethyldisiloxane and decamethyltetrasiloxane; the catalyst one is any one of potassium hydroxide silanol, sodium hydroxide silanol and (tetramethylammonium hydroxide) silicon alkoxide; the molar ratio of the monomer one to the monomer two is (5 to 10):1; the mass ratio of the catalyst one to the total of the monomer one and the monomer two is (1 to 5):100;

[0040] The crude product needs to be cross-linked by adding a cross-linking agent, and the cross-linking agent is any one of tetraethoxysilane, p-tolyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane and vinyltriethoxysilane; wherein the mass ratio of the cross-linking agent to the crude product is (1-10): (50-70);

[0041] The preparation steps of a pervaporation membrane for extracting flavor components from tobacco are as follows: a polyhydroxy macrocyclic compound is dispersed in a solvent to form a uniform solution, and a rubbery polymer is dispersed in the same solvent to form a uniform solution; the polyhydroxy macrocyclic compound solution is gradually added to the rubbery polymer solution under microwave-assisted mechanochemical action; after stirring evenly, a second catalyst is added while continuing to stir until the solution becomes viscous, thereby forming a casting solution; the casting solution is coated on the surface of a porous support membrane, first naturally dried at room temperature until a wet film is formed, and then thermally cross-linked at a temperature range of 30 to 90°C until the solvent is completely volatilized, thereby producing the pervaporation membrane for extracting flavor components from tobacco. The solvent is any one of n-heptane, n-hexane, benzene, toluene, dimethyl ether, and carbon tetrachloride; and the second catalyst is any one of dibutyltin dioctosilicate, stannous isooctanoate, and zinc isooctanoate.

[0042] The second aspect of the present invention discloses that the pervaporation membrane prepared by the preparation method is used for separating, extracting and recovering aroma substances in tobacco.

[0043] The pervaporation membrane for extracting flavor components from tobacco can be used for separating, extracting and recovering flavor components from tobacco, and can also be used for separating and extracting other flavor components.

[0044] The pervaporation membrane based on extracting flavor components from tobacco is used for pervaporation separation of flavor components in tobacco; the effective area of ​​membrane permeation is 8 to 30 cm 2 The feed liquid temperature is controlled at 15-90°C, the feed liquid flow rate is controlled at 10-1000 L / h, and the permeate side pressure is maintained at 0.1-10 kPa; the content of the fragrance components on the permeate side is tested by an ultraviolet spectrophotometer (UV) and a gas chromatography-mass spectrometer (GC-MS).

[0045] The following Comparative Example 1 and Examples 1 to 6 used a 6000 ppm aqueous solution of 2-phenylethanol as simulated tobacco extract 1, and subjected to separation and extraction. Example 7 used two flavoring substances, 2-phenylethanol and vanillin, to prepare simulated tobacco extract 2, wherein the 2-phenylethanol concentration was 6000 ppm and the vanillin concentration was 100 ppm, and subjected to separation and extraction. Example 8 used two flavoring substances, 2-phenylethanol and maltol, to prepare simulated tobacco extract 3, wherein the 2-phenylethanol concentration was 6000 ppm and the maltol concentration was 1000 ppm, and subjected to separation and extraction. In Examples 9 to 11, a total of 20 flavoring substances, including benzyl alcohol, phenylethyl alcohol, linalool, maltol, eugenol, guaiacol, methylcyclopentenolone, β-ionone, α-ionone, 2-methyltetrahydrofuran-3-one, menthone, benzyl acetate, linalyl acetate, γ-undecanoate, γ-undecalactone, 2-methylpyrazine, 2,6-lutidine, R-(+)-limonene, WS-3, and WS-23, were used to prepare a simulated tobacco extract 4, and separation and extraction were performed. In Example 12, an actual tobacco extract was used for separation and extraction.

[0046] The synthesis method of the rubbery polymer used in the comparative examples and examples is as follows: anhydrous octamethylcyclotetrasiloxane, tetramethyldisiloxane, and concentrated sulfuric acid are sequentially added to a three-necked flask, ensuring that the molar ratio of anhydrous octamethylcyclotetrasiloxane to tetramethyldisiloxane is 5:1 and the mass ratio of concentrated sulfuric acid to the total mass of anhydrous octamethylcyclotetrasiloxane and tetramethyldisiloxane is 4:100. The mixture is mechanically stirred and a chemical reaction is carried out. The chemical reaction is carried out under a nitrogen atmosphere using ultrasonic chemical synthesis at a temperature of 60°C with mechanical stirring. The reaction is allowed to proceed for 12 hours until the solution becomes viscous. The product is repeatedly washed 3 to 5 times with deionized water and 2 wt% sodium bicarbonate solution until the solution becomes neutral, thereby obtaining a crude rubbery polymer. Tetraethoxysilane is added to the crude product to ensure that the mass ratio of tetraethoxysilane to the crude product is 4:60. After thorough stirring until uniformly mixed, the rubbery polymer is obtained and is ready for use.

[0047] Comparative Example 1: Preparation of a pure rubber polymer film without adding a polyhydroxy macrocyclic compound, the steps are as follows:

[0048] A rubbery polymer was added to n-hexane to a concentration of 30.76 wt% and stirred thoroughly to form a solution. Dibutyltin disilicate was then added to the solution at a mass ratio of 60:1. The solution was stirred at 20°C until viscous, forming a casting solution. The casting solution was then applied to a porous polymer support membrane using a doctor blade coating machine, maintaining a wet film thickness of 150 μm. The membrane was dried at room temperature for 4 hours and then thermally crosslinked at 80°C for 36 hours to obtain a pure rubbery polymer membrane.

[0049] The prepared pure rubber polymer membrane was applied to simulated tobacco extract 1 for pervaporation separation. The temperature of the simulated tobacco extract 1 was 80°C and the flow rate was 90 L / h. After the pervaporation experiment ran stably, the total flux was measured to be 842.96 gm -2 h -1 , the separation factor of 2-phenylethanol is 7.14, and the pervaporation separation index is 5174.82gm -2 h -1 .

[0050] Example 1: Preparation of a pervaporation membrane for extracting flavor components from tobacco, the steps are as follows:

[0051] (1) Preparation of polyhydroxy macrocyclic compound 1

[0052] Potassium hydroxide was added to deionized water and stirred at room temperature for 20 minutes until completely dissolved, ensuring a potassium hydroxide concentration of 2.2 wt% in the aqueous solution, to prepare Solution B. β-cyclodextrin was added to Solution B, ensuring a β-cyclodextrin concentration of 5.26 wt%. The mixture was mechanically stirred at 25°C and 200 rpm for 1 hour until uniformly mixed, to prepare Solution C. Solution C was incubated in a methanol atmosphere at 25°C for 7 days. The crude product was collected and washed three times with methanol to remove the water of crystallization. The resulting product was dried under vacuum at 40°C for 24 hours to obtain a dry polyhydroxy macrocyclic compound 1, wherein the molar ratio of potassium hydroxide to β-cyclodextrin was 8:1.

[0053] (2) Preparation of pervaporation membranes for extracting flavor components from tobacco

[0054] A dried polyhydroxy macrocyclic compound 1 was added to n-hexane and ultrasonically dispersed at an ultrasonic frequency of 40 kHz and a temperature of 15°C for 3 hours to obtain a uniform dispersion E, ensuring that the mass fraction of the polyhydroxy macrocyclic compound 1 in the solution was 9.64 wt%; a rubbery polymer was added to n-hexane to ensure that the mass fraction of the rubbery polymer in the solution was 40 wt% and stirred evenly to prepare a solution F; solution F was added to solution E, wherein the volume ratio of solution F to solution E was 1:0.5, and stirred at 15°C for 8 hours to mix evenly to prepare a solution G; dibutyltin disilicate was added to solution G, wherein the mass ratio of rubbery polymer to dibutyltin disilicate was 60:1; stirring was continued at 15°C until it became viscous to prepare a casting solution H; and the casting solution H was coated on a porous support membrane using a coating machine, controlling the wet film thickness to be 150 μm. After the membrane was dried at room temperature for 4 hours, it was further thermally cross-linked at 80°C for 36 hours to obtain a pervaporation membrane for extracting flavor components from tobacco.

[0055] (3) using the pervaporation membrane prepared in step (2) for extracting flavor components from tobacco to extract flavor components from tobacco

[0056] The prepared pervaporation membrane based on extracting flavor components from tobacco was applied to simulated tobacco extract 1 for pervaporation separation. The temperature of the simulated tobacco extract 1 was 80°C and the flow rate was 90 L / h. After the pervaporation experiment ran stably, the total flux was measured to be 1150 g m -2 h -1 , the separation factor of 2-phenylethanol was 15, and the pervaporation separation index was 15900 g m -2 h -1 .

[0057] Example 2: Preparation of a pervaporation membrane for extracting flavor components from tobacco, the steps are as follows:

[0058] (1) Preparation of polyhydroxy macrocyclic compound 1

[0059] Potassium hydroxide was added to deionized water and stirred at room temperature for 30 minutes until completely dissolved, ensuring a potassium hydroxide concentration of 2.2 wt% in the aqueous solution, to prepare Solution B. β-cyclodextrin was added to Solution B, ensuring a β-cyclodextrin concentration of 5.26 wt%. The mixture was mechanically stirred at 25°C and 200 rpm for 2 hours until uniformly mixed, to prepare Solution C. Solution C was incubated in a methanol atmosphere at 25°C for 10 days. The crude product was collected and washed five times with methanol to remove the water of crystallization. The resulting product was dried under vacuum at 40°C for 24 hours to obtain a dry polyhydroxy macrocyclic compound 1, wherein the molar ratio of potassium hydroxide to β-cyclodextrin was 8:1.

[0060] (2) Preparation of pervaporation membranes for extracting flavor components from tobacco

[0061] A dried polyhydroxy macrocyclic compound 1 was added to n-hexane and ultrasonically dispersed for 2 hours at an ultrasonic frequency of 40 kHz and an ultrasonic temperature of 30°C to obtain a uniform dispersion E, ensuring that the mass fraction of the polyhydroxy macrocyclic compound 1 in the solution was 12.8 wt%. A rubbery polymer was added to n-hexane to ensure that the mass fraction of the rubbery polymer in the solution was 40 wt%, and stirred uniformly to prepare a solution F. Solution F was added to solution E, wherein the volume ratio of solution F to solution E was 1:0.5, and stirred at 30°C for 6 hours to mix uniformly to prepare a solution G. Dibutyltin diisocyanate was added to solution G, wherein the mass ratio of rubbery polymer to dibutyltin diisocyanate was 60:1. Stirring was continued at 30°C until it became viscous to prepare a casting solution H. Casting solution H was coated on a porous support membrane using a coating machine, and the wet film thickness was controlled to be 150 μm. After the membrane was dried at room temperature for 3 h, it was further thermally cross-linked at 80° C. for 36 h to obtain a pervaporation membrane for extracting flavor components from tobacco.

[0062] (3) using the pervaporation membrane prepared in step (2) for extracting flavor components from tobacco to extract flavor components from tobacco

[0063] The prepared pervaporation membrane based on extracting flavor components from tobacco was applied to simulated tobacco extract 1 for pervaporation separation. The temperature of the simulated tobacco extract 1 was 80°C and the flow rate was 90 L / h. After the pervaporation experiment ran stably, the total flux was measured to be 1186 g m -2 h -1 The separation factor of 2-phenylethanol was 21, and the pervaporation separation index was 24130 g m -2 h -1 .

[0064] Example 3: Based on the pervaporation membrane for extracting flavor components from tobacco, the steps are as follows:

[0065] (1) Preparation of polyhydroxy macrocyclic compound 1

[0066] Potassium hydroxide was added to deionized water and stirred at room temperature for 15 minutes until completely dissolved, ensuring a potassium hydroxide concentration of 2.2 wt% in the aqueous solution, to prepare Solution B. β-cyclodextrin was added to Solution B, ensuring a β-cyclodextrin concentration of 5.26 wt%. The mixture was mechanically stirred at 25°C and 200 rpm for 1 hour until uniformly mixed, to prepare Solution C. Solution C was incubated in a 30°C methanol atmosphere for 8 days. The crude product was collected and washed three times with methanol to remove the water of crystallization. The resulting product was dried under vacuum at 40°C for 24 hours to obtain polyhydroxy macrocyclic compound 1, wherein the molar ratio of potassium hydroxide to β-cyclodextrin was 8:1.

[0067] (2) Preparation of pervaporation membranes for extracting flavor components from tobacco

[0068] A dried polyhydroxy macrocyclic compound 1 was added to n-hexane and ultrasonically dispersed for 3 hours at an ultrasonic frequency of 40 kHz and an ultrasonic temperature of 20°C to obtain a uniform dispersion E, ensuring that the mass fraction of the polyhydroxy macrocyclic compound 1 in the solution was 12.8 wt%. A rubbery polymer was added to n-hexane to ensure that the mass fraction of the rubbery polymer in the solution was 40 wt%, and stirred uniformly to prepare a solution F. Solution F was added to solution E, wherein the volume ratio of solution F to solution E was 1:0.5, and stirred at 20°C for 4 hours to mix uniformly to prepare a solution G. Dibutyltin diisocyanate was added to solution G, wherein the mass ratio of rubbery polymer to dibutyltin diisocyanate was 60:1. Stirring was continued at 20°C until it became viscous to prepare a casting solution H. Casting solution H was coated on a porous support membrane using a coating machine, and the wet film thickness was controlled to be 200 μm. After the membrane was dried at room temperature for 5 h, it was further thermally cross-linked at 80° C. for 36 h to obtain a pervaporation membrane for extracting flavor components from tobacco.

[0069] (3) using the pervaporation membrane prepared in step (2) for extracting flavor components from tobacco to extract flavor components from tobacco

[0070] The prepared pervaporation membrane based on extracting flavor components from tobacco was applied to simulated tobacco extract 1 for pervaporation separation. The temperature of the simulated tobacco extract 1 was 80°C and the flow rate was 90 L / h. After the pervaporation experiment ran stably, the total flux was measured to be 1078 g m -2 h -1 The separation factor of 2-phenylethanol was 22, and the pervaporation separation index was 23260 g m -2 h -1 .

[0071] Example 4: Preparation of a pervaporation membrane for extracting flavor components from tobacco, the steps are as follows:

[0072] (1) Preparation of polyhydroxy macrocyclic compound 1

[0073] Potassium hydroxide was added to deionized water and stirred at room temperature for 30 minutes until completely dissolved, ensuring a potassium hydroxide concentration of 2.2 wt% in the aqueous solution, to prepare Solution B. β-cyclodextrin was added to Solution B, ensuring a β-cyclodextrin concentration of 5.26 wt%. The mixture was mechanically stirred at 25°C and 200 rpm for 2 hours until uniformly mixed, to prepare Solution C. Solution C was incubated in a methanol atmosphere at 30°C for 14 days. The crude product was collected and washed five times with methanol to remove the water of crystallization. The resulting product was dried under vacuum at 40°C for 24 hours to obtain polyhydroxy macrocyclic compound 1, wherein the molar ratio of potassium hydroxide to β-cyclodextrin was 8:1.

[0074] (2) Preparation of pervaporation membranes for extracting flavor components from tobacco

[0075] A dried polyhydroxy macrocyclic compound 1 was added to n-hexane and ultrasonically dispersed at an ultrasonic frequency of 40 kHz and an ultrasonic temperature of 15°C for 4 hours to obtain a uniform dispersion E, ensuring that the mass fraction of the polyhydroxy macrocyclic compound 1 in the solution was 12.8 wt%. A rubbery polymer was added to n-hexane to ensure that the mass fraction of the rubbery polymer in the solution was 40 wt%, and stirred uniformly to prepare a solution F. Solution F was added to solution E, wherein the volume ratio of solution F to solution E was 1:0.5, and stirred at 15°C for 5 hours to mix uniformly to prepare a solution G. Dibutyltin diisocyanate was added to solution G, wherein the mass ratio of rubbery polymer to dibutyltin diisocyanate was 60:1. Stirring was continued at 15°C until it became viscous to prepare a casting solution H. Casting solution H was coated on a porous support membrane using a coating machine, and the wet film thickness was controlled to be 250 μm. After the membrane was dried at room temperature for 3 h, it was further thermally cross-linked at 80° C. for 36 h to obtain a pervaporation membrane for extracting flavor components from tobacco.

[0076] (3) using the pervaporation membrane prepared in step (2) for extracting flavor components from tobacco to extract flavor components from tobacco

[0077] The prepared pervaporation membrane based on extracting flavor components from tobacco was applied to simulated tobacco extract 1 for pervaporation separation. The temperature of the simulated tobacco extract 1 was 80°C and the flow rate was 90 L / h. After the pervaporation experiment ran stably, the total flux was measured to be 835 g m -2 h -1 The separation factor of 2-phenylethanol was 26, and the pervaporation separation index was 21430 g m -2 h -1 .

[0078] Example 5: Preparation of a pervaporation membrane for extracting flavor components from tobacco, the steps are as follows:

[0079] (1) Preparation of polyhydroxy macrocyclic compound II

[0080] 4-tert-butylphenol, 37% formaldehyde aqueous solution and 10% sodium hydroxide aqueous solution are added to a three-necked flask, wherein the molar ratio of 4-tert-butylphenol to formaldehyde is 1:3, and the mass ratio of sodium hydroxide to the total amount of 4-tert-butylphenol and formaldehyde is 3:100. The mixture is reacted at 25°C for 12 hours using a microwave-assisted stirrer under nitrogen protection. Water is removed using a water separator during the reaction. After the reaction, rotary evaporation is used to dehydrate the mixture to obtain a brown viscous substance, which is a crude product of the polyhydroxy macrocyclic compound II. The crude product is washed with ethyl acetate and hydrochloric acid until neutral and then dried to obtain the polyhydroxy macrocyclic compound II.

[0081] (2) Preparation of pervaporation membranes for extracting flavor components from tobacco

[0082] A polyhydroxy macrocyclic compound II was added to n-hexane and ultrasonically dispersed at an ultrasonic frequency of 40 kHz and an ultrasonic temperature of 15° C. for 4 hours to obtain a uniform dispersion E, ensuring that the mass fraction of the polyhydroxy macrocyclic compound II in the solution was 9.64 wt %. A rubbery polymer was added to n-hexane to ensure that the mass fraction of the rubbery polymer in the solution was 40 wt %, and stirred uniformly to obtain a solution F. Solution F was added to solution E in a volume ratio of 1:1, and stirred at 15° C. for 5 hours to uniformly mix, to obtain a solution G. Dibutyltin diisocyanate was added to solution G in a mass ratio of 60:1 of rubbery polymer to dibutyltin diisocyanate. Stirring was continued at 15° C. until the solution became viscous, to obtain a casting solution H. Casting solution H was coated on a porous support membrane using a coating machine, and the wet film thickness was controlled to be 200 μm. After the membrane was dried at room temperature for 3 h, it was further thermally cross-linked at 80° C. for 36 h to obtain a pervaporation membrane for extracting flavor components from tobacco.

[0083] (3) using the pervaporation membrane prepared in step (2) for extracting flavor components from tobacco to extract flavor components from tobacco

[0084] The prepared pervaporation membrane based on extracting flavor components from tobacco was applied to simulated tobacco extract 1 for pervaporation separation. The temperature of the simulated tobacco extract 1 was 80°C and the flow rate was 90 L / h. After the pervaporation experiment ran stably, the total flux was measured to be 810 g m -2 h -1 The separation factor of 2-phenylethanol was 16, and the pervaporation separation index was 14780 g m -2 h -1 .

[0085] Example 6: Preparation of a pervaporation membrane for extracting flavor components from tobacco, the steps are as follows:

[0086] (1) Preparation of polyhydroxy macrocyclic compound II

[0087] 4-tert-butylphenol, 37% formaldehyde aqueous solution and 10% sodium hydroxide aqueous solution are added to a three-necked flask, wherein the molar ratio of 4-tert-butylphenol to formaldehyde is 1:3, and the mass ratio of sodium hydroxide to the total amount of 4-tert-butylphenol and formaldehyde is 3:100. The mixture is reacted at 25°C for 12 hours using a microwave-assisted stirrer under nitrogen protection. Water is removed using a water separator during the reaction. After the reaction, rotary evaporation is used to dehydrate the mixture to obtain a brown viscous substance, which is a crude product of the polyhydroxy macrocyclic compound II. The crude product is washed with ethyl acetate and hydrochloric acid until neutral and then dried to obtain the polyhydroxy macrocyclic compound II.

[0088] (2) Preparation of pervaporation membranes for extracting flavor components from tobacco

[0089] A dried polyhydroxy macrocyclic compound II was added to n-hexane and ultrasonically dispersed for 4 hours at an ultrasonic frequency of 40 kHz and an ultrasonic temperature of 15°C to obtain a uniform dispersion E, ensuring that the mass fraction of the polyhydroxy macrocyclic compound II in the solution was 9.64 wt%. A rubbery polymer was added to n-hexane to ensure that the mass fraction of the rubbery polymer in the solution was 40 wt%, and stirred uniformly to prepare a solution F. Solution F was added to solution E, wherein the volume ratio of solution F to solution E was 1:1, and stirred at 15°C for 5 hours to mix uniformly to prepare a solution G. Dibutyltin diisocyanate was added to solution G, wherein the mass ratio of rubbery polymer to dibutyltin diisocyanate was 60:1. Stirring was continued at 15°C until it became viscous to prepare a casting solution H. Casting solution H was coated on a porous support membrane using a coating machine, and the wet film thickness was controlled to be 200 μm. After the membrane was dried at room temperature for 3 h, it was further thermally cross-linked at 80° C. for 36 h to obtain a pervaporation membrane for extracting flavor components from tobacco.

[0090] (3) using the pervaporation membrane prepared in step (2) for extracting flavor components from tobacco to extract flavor components from tobacco

[0091] The prepared pervaporation membrane based on extracting flavor components from tobacco was applied to simulated tobacco extract 1 for pervaporation separation. The temperature of the simulated tobacco extract 1 was 80°C and the flow rate was 60 L / h. After the pervaporation experiment ran stably, the total flux was measured to be 1389 g m -2 h -1 The separation factor of 2-phenylethanol was 4, and the pervaporation separation index was 8980 g m -2 h -1 .

[0092] Example 7: Preparation of a pervaporation membrane for extracting flavor components from tobacco, the steps are as follows:

[0093] (1) Preparation of polyhydroxy macrocyclic compound 1

[0094] Potassium hydroxide was added to deionized water and stirred at room temperature for 40 minutes until completely dissolved, ensuring a potassium hydroxide concentration of 2.2 wt% in the aqueous solution, to prepare Solution B. β-cyclodextrin was slowly added to Solution B, ensuring a β-cyclodextrin concentration of 5.26 wt%. The mixture was mechanically stirred at 25°C and 200 rpm for 1 hour until uniformly mixed, to prepare Solution C. Solution C was incubated in a methanol atmosphere at 25°C for 7 days. The crude product was collected and washed four times with methanol to remove the water of crystallization. The resulting product was dried under vacuum at 40°C for 24 hours to obtain a dry polyhydroxy macrocyclic compound 1, wherein the molar ratio of potassium hydroxide to β-cyclodextrin was 8:1.

[0095] (2) Preparation of pervaporation membranes for extracting flavor components from tobacco

[0096] A dried polyhydroxy macrocyclic compound 1 was added to n-hexane and ultrasonically dispersed for 5 hours at an ultrasonic frequency of 40 kHz and an ultrasonic temperature of 20°C to obtain a uniform dispersion E, ensuring that the mass fraction of the polyhydroxy macrocyclic compound 1 in the solution was 12.8 wt%. A rubbery polymer was added to n-hexane to ensure that the mass fraction of the rubbery polymer in the solution was 40 wt%, and stirred uniformly to obtain a solution F. Solution F was slowly added to solution E, wherein the volume ratio of solution F to solution E was 1:0.5, and stirred at 20°C for 4 hours to uniformly mix, to obtain a solution G. Dibutyltin diisocyanate was added to solution G, wherein the mass ratio of rubbery polymer to dibutyltin diisocyanate was 60:1. Stirring was continued at 20°C until it became viscous, to obtain a casting solution H. Casting solution H was coated on a porous support membrane using a coating machine, and the wet film thickness was controlled to be 150 μm. After the membrane was dried at room temperature for 6 h, it was further thermally cross-linked at 80° C. for 36 h to obtain a pervaporation membrane for extracting flavor components from tobacco.

[0097] (3) using the pervaporation membrane prepared in step (2) for extracting flavor components from tobacco to extract flavor components from tobacco

[0098] The prepared pervaporation membrane based on extracting flavor components from tobacco was applied to simulated tobacco extract 2 for pervaporation separation. The temperature of the simulated tobacco extract 2 was 80°C and the flow rate was 90 L / h. After the pervaporation experiment ran stably, the total flux was measured to be 1320 g m -2 h -1 , the separation factor of 2-phenylethanol / water is 14, the separation factor of vanillin / water is 0.96, and the separation factor of 2-phenylethanol / vanillin is 15.

[0099] Example 8: Preparation of a pervaporation membrane for extracting flavor components from tobacco, the steps are as follows:

[0100] (1) Preparation of polyhydroxy macrocyclic compound 1

[0101] Potassium hydroxide was added to deionized water and stirred at room temperature for 20 minutes until completely dissolved, ensuring a potassium hydroxide concentration of 2.2 wt% in the aqueous solution, to prepare Solution B. β-cyclodextrin was slowly added to Solution B, ensuring a β-cyclodextrin concentration of 5.26 wt%. The mixture was mechanically stirred at 25°C and 200 rpm for 2 hours until uniformly mixed, to prepare Solution C. Solution C was incubated in a 30°C methanol atmosphere for 10 days. The crude product was collected and washed three times with methanol to remove the water of crystallization. The resulting product was dried under vacuum at 40°C for 24 hours to obtain a dry polyhydroxy macrocyclic compound 1, wherein the molar ratio of potassium hydroxide to β-cyclodextrin was 8:1.

[0102] (2) Preparation of pervaporation membranes for extracting flavor components from tobacco

[0103] A dried polyhydroxy macrocyclic compound 1 was added to n-hexane and ultrasonically dispersed at an ultrasonic frequency of 40 kHz and an ultrasonic temperature of 25° C. for 4 hours to obtain a uniform dispersion E, ensuring that the mass fraction of the polyhydroxy macrocyclic compound 1 in the solution was 12.8 wt %. A rubbery polymer was added to n-hexane, ensuring that the mass fraction of the rubbery polymer in the solution was 40 wt %, and stirred uniformly to obtain a solution F. Solution F was slowly added to solution E, wherein the volume ratio of solution F to solution E was 1:0.5, and stirred at 25° C. for 4 hours to mix uniformly to obtain a solution G. Dibutyltin diisocyanate was added to solution G, wherein the mass ratio of rubbery polymer to dibutyltin diisocyanate was 60:1. Stirring was continued at 25° C. until it became viscous to obtain a casting solution H. Casting solution H was coated on a porous support membrane using a coating machine, and the wet film thickness was controlled to be 150 μm. After the membrane was dried at room temperature for 5 h, it was further thermally cross-linked at 80° C. for 36 h to obtain a pervaporation membrane for extracting flavor components from tobacco.

[0104] (3) using the pervaporation membrane prepared in step (2) for extracting flavor components from tobacco to extract flavor components from tobacco

[0105] The prepared pervaporation membrane based on extracting flavor components from tobacco was applied to simulated tobacco extract 3 for pervaporation separation. The temperature of the simulated tobacco extract 3 was 80°C and the flow rate was 90 L / h. After the pervaporation experiment ran stably, the total flux was measured to be 1250 g m -2 h -1 , the separation factor of 2-phenylethanol / water is 18, the separation factor of maltol / water is 1.3, and the separation factor of 2-phenylethanol / maltol is 14.

[0106] Example 9: Preparation of a pervaporation membrane for extracting flavor components from tobacco, the steps are as follows:

[0107] (1) Preparation of polyhydroxy macrocyclic compound 1

[0108] Potassium hydroxide was added to deionized water and stirred at room temperature for 40 minutes until completely dissolved, ensuring a potassium hydroxide concentration of 2.2 wt% in the aqueous solution, to prepare Solution B. β-cyclodextrin was added to Solution B, ensuring a β-cyclodextrin concentration of 5.26 wt%. The mixture was mechanically stirred at 25°C and 200 rpm for 1 hour until uniformly mixed, to prepare Solution C. Solution C was incubated in a 30°C methanol atmosphere for 7 days. The crude product was collected and washed four times with methanol to remove the water of crystallization. The resulting product was dried under vacuum at 40°C for 24 hours to obtain a dry polyhydroxy macrocyclic compound 1, wherein the molar ratio of potassium hydroxide to β-cyclodextrin was 8:1.

[0109] (2) Preparation of pervaporation membranes for extracting flavor components from tobacco

[0110] A dried polyhydroxy macrocyclic compound 1 was added to n-hexane and ultrasonically dispersed for 5 hours at an ultrasonic frequency of 40 kHz and an ultrasonic temperature of 20°C to obtain a uniform dispersion E, ensuring that the mass fraction of the polyhydroxy macrocyclic compound 1 in the solution was 3.85 wt%. A rubbery polymer was added to n-hexane to ensure that the mass fraction of the rubbery polymer in the solution was 40 wt%, and stirred uniformly to prepare a solution F. Solution F was added to solution E, wherein the volume ratio of solution F to solution E was 1:0.5, and stirred at 20°C for 4 hours to mix uniformly to prepare a solution G. Dibutyltin diisocyanate was added to solution G, wherein the mass ratio of rubbery polymer to dibutyltin diisocyanate was 60:1. Stirring was continued at 20°C until it became viscous to prepare a casting solution H. Casting solution H was coated on a porous support membrane using a coating machine, and the wet film thickness was controlled to be 150 μm. After the membrane was dried at room temperature for 6 h, it was further thermally cross-linked at 80° C. for 36 h to obtain a pervaporation membrane for extracting flavor components from tobacco.

[0111] (3) using the pervaporation membrane prepared in step (2) for extracting flavor components from tobacco to extract flavor components from tobacco

[0112] The prepared pervaporation membrane based on extracting flavor components from tobacco was applied to simulated tobacco extract 4 for pervaporation separation. The temperature of the simulated tobacco extract 4 was 60°C and the flow rate was 40 L / h. After the pervaporation experiment ran stably, the separation performance of the following substances was measured as shown in the following table:

[0113]

[0114]

[0115] Example 10: Preparation of a pervaporation membrane for extracting flavor components from tobacco, the steps are as follows:

[0116] (1) Preparation of polyhydroxy macrocyclic compound 1

[0117] Potassium hydroxide was added to deionized water and stirred at room temperature for 20 minutes until completely dissolved, ensuring a potassium hydroxide concentration of 2.2 wt% in the aqueous solution, to prepare Solution B. β-cyclodextrin was added to Solution B, ensuring a β-cyclodextrin concentration of 5.26 wt%. The mixture was mechanically stirred at 30°C and 100 rpm for 2 hours until uniformly mixed, to prepare Solution C. Solution C was incubated in a 30°C methanol atmosphere for 10 days. The crude product was collected and washed three times with methanol to remove the water of crystallization. The resulting product was dried under vacuum at 40°C for 24 hours to obtain a dry polyhydroxy macrocyclic compound 1, wherein the molar ratio of potassium hydroxide to β-cyclodextrin was 8:1.

[0118] (2) Preparation of pervaporation membranes for extracting flavor components from tobacco

[0119] A dried polyhydroxy macrocyclic compound 1 was added to n-hexane and ultrasonically dispersed at an ultrasonic frequency of 40 kHz and an ultrasonic temperature of 25°C for 4 hours to obtain a uniform dispersion E, ensuring that the mass fraction of the polyhydroxy macrocyclic compound 1 in the solution was 10.71 wt%. A rubbery polymer was added to n-hexane to ensure that the mass fraction of the rubbery polymer in the solution was 40 wt%, and stirred uniformly to prepare a solution F. Solution F was added to solution E, wherein the volume ratio of solution F to solution E was 1:0.5, and stirred at 25°C for 4 hours to mix uniformly to prepare a solution G. Dibutyltin diisocyanate was added to solution G, wherein the mass ratio of rubbery polymer to dibutyltin diisocyanate was 60:1. Stirring was continued at 25°C until it became viscous to prepare a casting solution H. Casting solution H was coated on a porous support membrane using a coating machine, and the wet film thickness was controlled to be 150 μm. After the membrane was dried at room temperature for 5 hours, it was further thermally cross-linked at 80°C for 36 hours to obtain a pervaporation membrane for extracting flavor components from tobacco.

[0120] (3) using the pervaporation membrane prepared in step (2) for extracting flavor components from tobacco to extract flavor components from tobacco

[0121] The prepared pervaporation membrane based on extracting flavor components from tobacco was applied to simulated tobacco extract 4 for pervaporation separation. The temperature of the simulated tobacco extract 4 was 60°C and the flow rate was 40 L / h. After the pervaporation experiment ran stably, the separation performance of the following substances was measured as shown in the following table:

[0122]

[0123] Example 11: Preparation of a pervaporation membrane for extracting flavor components from tobacco, the steps are as follows:

[0124] (1) Preparation of polyhydroxy macrocyclic compound 1

[0125] Potassium hydroxide was added to deionized water and stirred at room temperature for 40 minutes until completely dissolved, ensuring a potassium hydroxide concentration of 2.2 wt% in the aqueous solution, to prepare Solution B. β-cyclodextrin was added to Solution B, ensuring a β-cyclodextrin concentration of 5.26 wt%. The mixture was mechanically stirred at 25°C and 200 rpm for 1 hour until uniformly mixed, to prepare Solution C. Solution C was incubated in a 30°C methanol atmosphere for 7 days. The crude product was collected and washed four times with methanol to remove the water of crystallization. The resulting product was dried under vacuum at 40°C for 24 hours to obtain a dry polyhydroxy macrocyclic compound 1, wherein the molar ratio of potassium hydroxide to β-cyclodextrin was 8:1.

[0126] (2) Preparation of pervaporation membranes for extracting flavor components from tobacco

[0127] A dried polyhydroxy macrocyclic compound 1 was added to n-hexane and ultrasonically dispersed for 2 hours at an ultrasonic frequency of 40 kHz and an ultrasonic temperature of 15°C to obtain a uniform dispersion E, ensuring that the mass fraction of the polyhydroxy macrocyclic compound 1 in the solution was 11.76 wt%. A rubbery polymer was added to n-hexane to ensure that the mass fraction of the rubbery polymer in the solution was 40 wt%, and stirred uniformly to prepare a solution F. Solution F was added to solution E, wherein the volume ratio of solution F to solution E was 1:0.5, and stirred at 15°C for 6 hours to mix uniformly to prepare a solution G. Dibutyltin dilaurate was added to solution G, wherein the mass ratio of rubbery polymer to dibutyltin dilaurate was 60:1. Stirring was continued at 15°C until it became viscous to prepare a casting solution H. Casting solution H was coated on a porous support membrane using a coating machine, and the wet film thickness was controlled to be 150 μm. After the membrane was dried at room temperature for 6 h, it was further thermally cross-linked at 80° C. for 36 h to obtain a pervaporation membrane for extracting flavor components from tobacco.

[0128] (3) using the pervaporation membrane prepared in step (2) to extract the flavor components in tobacco

[0129] The prepared pervaporation membrane based on extracting flavor components from tobacco was applied to simulated tobacco extract 4 for pervaporation separation. The temperature of the simulated tobacco extract 4 was 60°C and the flow rate was 40 L / h. After the pervaporation experiment ran stably, the separation performance of the following substances was measured as shown in the following table:

[0130]

[0131] Example 12: Preparation of a pervaporation membrane for extracting flavor components from tobacco, the steps are as follows:

[0132] (1) Preparation of polyhydroxy macrocyclic compound 1

[0133] Potassium hydroxide was added to deionized water and stirred at room temperature for 20 minutes until completely dissolved, ensuring a potassium hydroxide concentration of 2.2 wt% in the aqueous solution, to prepare Solution B. β-cyclodextrin was added to Solution B, ensuring a β-cyclodextrin concentration of 5.26 wt%. The mixture was mechanically stirred at 25°C and 200 rpm for 2 hours until uniformly mixed, to prepare Solution C. Solution C was incubated in a 30°C methanol atmosphere for 8 days. The crude product was collected and washed three times with methanol to remove the water of crystallization. The resulting product was dried under vacuum at 40°C for 24 hours to obtain a dry polyhydroxy macrocyclic compound 1, wherein the molar ratio of potassium hydroxide to β-cyclodextrin was 8:1.

[0134] (2) Preparation of pervaporation membranes for extracting flavor components from tobacco

[0135] A dried polyhydroxy macrocyclic compound 1 was added to n-hexane and ultrasonically dispersed for 2 hours at an ultrasonic frequency of 40 MHz and an ultrasonic temperature of 30° C. to obtain a uniform dispersion E, ensuring that the mass fraction of the polyhydroxy macrocyclic compound 1 in the solution was 12.8 wt %. A rubbery polymer was added to n-hexane to ensure that the mass fraction of the rubbery polymer in the solution was 40 wt %, and stirred uniformly to obtain a solution F. Solution F was added to solution E, wherein the volume ratio of solution F to solution E was 1:0.5, and stirred at 30° C. for 4 hours to uniformly mix, to obtain a solution G. Dibutyltin diisocyanate was added to solution G, wherein the mass ratio of rubbery polymer to dibutyltin diisocyanate was 60:1. Stirring was continued at 30° C. until it became viscous, to obtain a casting solution H. Casting solution H was coated on a porous support membrane using a coating machine, and the wet film thickness was controlled to be 150 μm. After the membrane was dried at room temperature for 2 h, it was further thermally cross-linked at 80° C. for 36 h to obtain a pervaporation membrane for extracting flavor components from tobacco.

[0136] (3) using the pervaporation membrane prepared in step (2) for extracting flavor components from tobacco to extract flavor components from tobacco

[0137] The prepared pervaporation membrane for extracting flavor components from tobacco was applied to actual tobacco extract for pervaporation separation. The temperature of the actual tobacco extract was 60°C and the flow rate was 40 L / h. After the pervaporation experiment ran stably, the separation performance of the following substances was measured as shown in the following table:

[0138]

[0139] The results of the Comparative Examples and Examples above demonstrate that, compared to Comparative Example 1, the pervaporation membranes prepared in Examples 1 and 2, with varying amounts of polyhydroxy macrocyclic compounds added, exhibit superior separation performance for 2-phenylethanol compared to pure rubbery polymer membranes without polyhydroxy macrocyclic compounds. This is because polyhydroxy macrocyclic compounds have large hydrophobic cavities and abundant hydroxyl groups, which can form hydrogen bonds with flavor components in tobacco. This reduces the mass transfer resistance of flavor components through the membrane, facilitates preferential permeation of flavor components through the membrane, and enhances the pervaporation membrane's selective separation performance for flavor components.

[0140] Comparing Examples 2 to 4, an increase in membrane thickness will result in more 2-phenylethanol being adsorbed in the membrane during the pervaporation process, and the concentration of 2-phenylethanol in the membrane will increase, resulting in an increase in the diffusion coefficient of 2-phenylethanol in the membrane, and the transfer rate of 2-phenylethanol molecules is stronger than that of water; therefore, the separation performance of the prepared pervaporation membrane for extracting flavor components from tobacco for 2-phenylethanol increases with increasing membrane thickness.

[0141] Comparative Examples 1, 5 and 6, in which polyhydroxy macrocyclic compound 1 and polyhydroxy macrocyclic compound 2 were added, respectively, were used to prepare pervaporation membranes based on polyhydroxy macrocyclic compounds. By comparing the permeation performance data of 2-phenylethanol, it was found that the pervaporation membrane with the addition of polyhydroxy macrocyclic compound 1 had better permeability and selectivity for 2-phenylethanol. This may be because the large number of effective hydroxyl groups of polyhydroxy macrocyclic compound 1 and its unique cage structure are more suitable for the permeation of alcohol fragrance molecules.

[0142] Compared with Example 2, the total flux of the membranes of Examples 7 and 8 increased, while the separation performance for 2-phenylethanol decreased. This is because the addition of vanillin or maltol increases the content of flavor components adsorbed in the membrane, leading to increased membrane swelling and free volume, thus increasing the total flux. However, due to the fixed adsorption sites in the membrane, the addition of vanillin or maltol competes with 2-phenylethanol for adsorption, resulting in a decrease in the amount of 2-phenylethanol adsorbed in the membrane and a decrease in the membrane's separation performance for 2-phenylethanol.

[0143] Comparative Examples 9 to 11 show that the pervaporation membrane has a certain separation effect on the fragrance components of benzyl alcohol, 2-methyltetrahydrofuran-3-one, 2-methylpyrazine and R-(+)-limonene, and the separation performance is enhanced with the increase of the added amount of polyhydroxy macrocyclic compound, indicating that the pervaporation membrane has a certain separation effect on the multi-component fragrance component system.

[0144] In Example 12, actual tobacco extract was separated and extracted, wherein the concentrations of 1,3-di-tert-butylbenzene, 1,4-diacetobenzene, 2,4-di-tert-butylphenol, megastigmatrienone, and palmitic acid in the permeate increased by more than 2 times, indicating that the pervaporation membrane based on the extraction of flavor components in tobacco has a certain separation and purification effect on the flavor components in the actual tobacco extract, and therefore can be used for the pervaporation separation of various flavor components in tobacco.

Claims

1. A composite pervaporation membrane, characterized in that: The composite pervaporation membrane is composed of a porous support membrane and a continuous membrane layer located thereon, wherein the continuous membrane layer is a composite of a polyhydroxy macrocyclic compound and a rubber polymer. The polyhydroxy macrocyclic compound and the rubber polymer molecules are connected by weak hydrogen bonds between the two materials, thereby forming an interconductive network structure. The polyhydroxy macrocyclic compound is a macrocyclic compound having "cylindrical" annular macropores and having a plurality of hydroxyl groups on the surface of the cyclic molecule. The polyhydroxy macrocyclic compound is prepared by the following method: adding cyclodextrin to a solution containing a metal ion compound with a mass fraction of 0.5 to 15 wt% and mixing evenly, wherein the mass fraction of cyclodextrin in the mixed solution is 1 to 10 wt%; placing the mixed solution in a methanol protective atmosphere at 15 to 60° C. and growing for 1 to 21 days; The crude product is collected; washed and dried to obtain a polyhydroxy macrocyclic compound, wherein the metal ion-containing compound is any one of potassium nitrate, potassium hydroxide and potassium benzoate.

2. The composite pervaporation membrane according to claim 1, characterized in that: The rubbery polymer is prepared as follows: Monomer 1, monomer 2, and catalyst 1 are sequentially added to a three-necked flask, stirred and mixed to allow a chemical reaction to occur, wherein the chemical reaction is carried out using ultrasonic chemical synthesis under a nitrogen atmosphere, and the reaction is terminated when the solution becomes viscous; after the reaction is completed, the solution is washed with deionized water and a 2% sodium bicarbonate solution until neutral to obtain a crude rubber polymer product; a crosslinking agent is added to the crude product, and the mixture is thoroughly stirred until uniformly mixed to obtain the rubber polymer; The chemical synthesis reaction is carried out in a nitrogen protective atmosphere by ultrasonic chemical synthesis at a temperature range of 50-90°C for 4-24 hours; the monomer one is an anhydrous material, and the material type is any one of hexamethylcyclotrisiloxane, hexaethylcyclotrisiloxane, octamethylcyclotetrasiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane and decamethylcyclopentasiloxane; the monomer two is any one of divinyltetramethyldisiloxane, 1,1,3,3-tetramethyldisiloxane, hexamethyldisiloxane and decamethyltetrasiloxane; the catalyst one is any one of potassium hydroxide silanol, sodium hydroxide silanol and (tetramethylammonium hydroxide) silicon alkoxide; the molar ratio of the monomer one to the monomer two is (5-10):1; the mass of the catalyst one is 1-5% of the total mass of the monomer one and the monomer two; The crosslinking agent is any one of tetraethoxysilane, p-tolyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane and vinyltriethoxysilane; the mass ratio of the crosslinking agent to the crude product is (1-10): (50-70).

3. The composite pervaporation membrane according to claim 1, characterized in that: The composite pervaporation membrane is prepared as follows: A polyhydroxy macrocyclic compound is dispersed in a solvent to prepare a uniform solution A with a mass fraction of 1 to 25 wt%; a rubbery polymer is dispersed in the same solvent to prepare a uniform solution B with a mass fraction of 5 to 50 wt%; the polyhydroxy macrocyclic compound solution A is gradually added to the rubbery polymer solution B under microwave-assisted mechanochemical action, with the volume ratio of solution B to solution A being 1:(0.1 to 5); after stirring evenly, a catalyst 2 is added while continuing to stir until the solution becomes viscous, which is a casting solution C, and the mass ratio of catalyst 2 to polyhydroxy macrocyclic compound is (1 to 30):100; the casting solution C is coated on the surface of a porous support membrane, first naturally dried at room temperature until a wet membrane is formed, and then thermally cross-linked at a temperature range of 30 to 90° C. until the solvent is completely volatilized, thereby preparing the pervaporation membrane for extracting flavor components from tobacco; The solvent is any one of n-heptane, n-hexane, benzene, toluene, dimethyl ether and carbon tetrachloride; and the catalyst 2 is any one of dibutyltin dilaurate, stannous isooctanoate and zinc isooctanoate.

4. Use of the pervaporation membrane according to any one of claims 1 to 3 in separating, extracting and recovering flavor components in tobacco.

5. A method for separating flavor components in tobacco, characterized in that: The tobacco extract to be extracted is passed through the pervaporation membrane according to any one of claims 1 to 3, with the tobacco extract having a temperature of 40 to 90° C. and a flow rate of 10 to 200 L / h.

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