A separation membrane for oil-containing water body in refining process of bupleurum volatile oil, and a preparation method and application thereof

Abstract

The application discloses a kind of oil-containing water body separation membrane for refining process of Bupleurum volatile oil and preparation method and application.The preparation method of the application is first mixed and dissolved according to proportion with cellulose acetate and cellulose nitrate powder, form casting membrane liquid, and the base membrane is prepared using non-solvent phase conversion method;Second, the film is deacetylated;After that, it is soaked in acyl chloride n-hexane solution for crosslinking;Finally, by in-situ hydrolysis of silane coupling agent on the membrane surface, a hydrophobic surface is prepared, and an oil-containing water body separation membrane for refining process of Bupleurum volatile oil is obtained.This method forms a hydrophobic layer on the surface of the membrane, which strengthens the rapid passage of Bupleurum volatile oil molecules and inhibits the penetration of water;Using the oil-containing water body separation membrane avoids the formation of emulsion during oil-water separation, showing high separation efficiency and stability, and widening the application of cellulose acetate membrane in traditional Chinese medicine preparation process.

Description

Technical Field

[0001] This invention belongs to the field of extraction and separation of Bupleurum chinense volatile oil in the preparation of traditional Chinese medicine, and particularly relates to a membrane for separating oil-containing water bodies in the refining process of Bupleurum chinense volatile oil, its preparation method and application. Background Technology

[0002] Bupleurum chinense volatile oil is a volatile oily liquid found in medicinal plants and is an important component of the efficacy of traditional Chinese medicine. In the preparation of traditional Chinese medicine, the extraction of Bupleurum chinense volatile oil typically employs steam distillation (a two-step process: ① steam distillation of the medicinal material to obtain an oil-containing aqueous solution, ② oil-water separation to obtain the Bupleurum chinense volatile oil). However, the oil-water mixture is prone to emulsification, leading to difficulties in separation and resulting in a low yield of Bupleurum chinense volatile oil. Membrane separation has gained favor among researchers due to its lack of phase change, low cost, solvent resistance, and thermal stability.

[0003] Currently, the most widely used commercially available oil-water separation polymer membranes include cellulose acetate, cellulose nitrate, nylon membranes, polysulfone, polyethersulfone, and polyvinylidene fluoride. Cellulose acetate, as a porous membrane, possesses advantages such as high mechanical properties, low cost, high permeability, and simple processing, making it particularly valuable for development and utilization in the field of traditional Chinese medicine preparations. However, cellulose acetate membranes are prone to forming a water film deposition layer, preventing further oil-phase separation and resulting in low oil-water separation efficiency and high energy consumption, which significantly limits the development of this material. Summary of the Invention

[0004] This invention addresses the problem that cellulose acetate membranes easily form water film deposits during oil-water separation in the refining process of Bupleurum chinense volatile oil, resulting in low oil-water separation efficiency. The invention provides a thin film for separating oil-containing water bodies during the refining process of Bupleurum chinense volatile oil, along with its preparation method and application.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A method for preparing an oil-water separation membrane in the refining process of Bupleurum chinense volatile oil includes the following steps:

[0007] Cellulose acetate and cellulose nitrate powders are mixed and dissolved according to a preset mass ratio to form a casting solution; the casting solution is coated into a film and then immersed in a non-solvent phase to precipitate a thin film; after the film solidifies, the film is washed by immersing it in deionized water.

[0008] The washed membrane was immersed in an alkaline solution and reacted for a preset time to obtain a deacetylated membrane. The deacetylated membrane was then removed, washed with deionized water, and dried.

[0009] The dried deacetylated film was immersed in a hexane solution of acyl chloride and reacted for a preset time to obtain an acyl chloride crosslinked film. The acyl chloride crosslinked film was then removed, washed with deionized water, and dried.

[0010] Different concentrations of silane coupling agent aqueous solutions were prepared. The dried acyl chloride crosslinked membrane was immersed in the silane coupling agent aqueous solution, the pH of the solution was adjusted, and after the silane coupling agent underwent hydrolysis reaction for a preset time, it was taken out and dried to obtain the oil-water separation membrane.

[0011] The concentration of the acyl chloride is 0.005 mol / L to 0.02 mol / L.

[0012] The acyl chloride is one of 1,3,5-benzenetricarboxyl chloride, terephthaloyl chloride, o-phthaloyl chloride, isophthaloyl chloride, octanoyl chloride, adipyl chloride, glutaryl chloride, sebacyl chloride, azeloyl chloride, methylmalonyl chloride, 1,7-heptanoyl chloride, 2,6-naphthalenedilicate chloride, 2,5-furandicarboxyl chloride, hexafluoroglutaryl chloride, tetrafluorosuccinyl chloride, octafluoroadipyl chloride, 3-methyladipyl chloride, or 1,4-benzenediacryl chloride.

[0013] The mass concentration of the aqueous solution of the silane coupling agent is 0.01 g / L to 10 g / L.

[0014] The hydrolysis time of the silane coupling agent is 0~48 h.

[0015] The hydrolysis pH of the silane coupling agent is 3-13.

[0016] The silane coupling agent is one of the following: dodecyltrimethoxysilane, dodecyltriethoxysilane, hexadecyltrimethoxysilane, hexadecyltriethoxysilane, octadecyltrimethoxysilane, octadecyltriethoxysilane, octadecyldimethylmethoxysilane, octyltrimethoxysilane, n-octyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(β-methoxyethoxy)silane, methacryloxysilane, isobutyltriethoxysilane, butyldimethylchlorosilane, butyltriethoxysilane, pentyltriethoxysilane, isobutyltriethoxysilane, hexyltriethoxysilane, methyltriacetoxysilane, octylmethyldimethoxysilane, propyltrimethoxysilane, or hexyltrimethoxysilane.

[0017] The concentration of the alkaline solution is 0.01 mol / L to 0.2 mol / L, and the soaking time in the alkaline solution is 1 min to 25 h.

[0018] A method for preparing an oil-water separation membrane for use in the refining of Bupleurum chinense volatile oil, wherein the surface of the prepared oil-water separation membrane is connected with silane groups.

[0019] The aforementioned oil-water separation membrane is used in the oil-water separation process of Bupleurum chinense volatile oil refining.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] This method involves preparing a base membrane by blending cellulose acetate and cellulose nitrate, followed by deacetylation, acyl chloride crosslinking, and in-situ hydrolytic coupling with silanes to obtain an oil-water separation membrane for use in the refining of Bupleurum chinense volatile oil. This method is simple and easy to implement. On the one hand, the deacetylation treatment forms abundant hydroxyl structures on the membrane surface, and subsequent crosslinking and silane modification create a hydrophobic layer, enhancing the rapid passage of Bupleurum chinense volatile oil molecules while inhibiting water permeation. On the other hand, using this oil-water separation membrane avoids emulsion formation during oil-water separation, exhibiting high separation efficiency and stability, thus broadening the application of cellulose acetate membranes in traditional Chinese medicine preparations. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below:

[0023] Figure 1 This is a diagram showing the characteristics of the film prepared in Example 7 of the present invention in contact with water in an oil solution;

[0024] Figure 2 (a) is a test graph of the hydrophilic and hydrophobic properties of the thin film prepared in the comparative example of the present invention; (b) is a test graph of the hydrophilic and hydrophobic properties of the thin film prepared in Example 7 of the present invention.

[0025] Figure 3 The image shows the FTIR spectrum of the thin film prepared in Example 7 of this invention.

[0026] Figure 4 The TGA spectra of the thin films prepared in Example 7 and the comparative example of the present invention are shown below.

[0027] Figure 5 (a) is a SEM image of the film prepared in the comparative example of the present invention; (b) is a SEM image of the film after crosslinking with 1,3,5-benzenetricarboxylic acid chloride in step 3 of Example 7 of the present invention; (c) is a SEM image of the film after in-situ hydrolysis of n-octyltrimethoxysilane in step 4 of Example 7 of the present invention. Detailed Implementation

[0028] The present invention will be further described below with reference to the accompanying drawings:

[0029] The purpose of this invention is to provide a membrane for separating oil and water in the refining process of Bupleurum chinense volatile oil, its preparation method, and its application. The preparation of this membrane expands the application of cellulose acetate membranes in traditional Chinese medicine preparation processes and solves the problems of easy emulsification and low separation efficiency during the oil-water separation process in the refining of Bupleurum chinense volatile oil.

[0030] A method for preparing an oil-water separation membrane in the refining process of Bupleurum chinense volatile oil involves cross-linking and in-situ hydrolyzing silane groups on the surface of a pretreated base membrane to form an oil-water separation membrane. Specifically, the method includes the following steps:

[0031] S1: Mix and dissolve cellulose acetate and cellulose nitrate powder in a certain mass ratio to form a uniform casting solution. After removing air bubbles from the casting solution, pour it onto a glass plate and coat it into a film. Then, immediately immerse it in a non-solvent phase to precipitate and obtain a thin film. After the film has completely solidified, peel the prepared film off the glass plate and wash the film by immersing it in deionized water.

[0032] S2: Immerse the washed film in an alkaline solution and react for a preset time to obtain a deacetylated film. Take out the deacetylated film, wash it with deionized water, and dry it.

[0033] S3: Immerse the dried deacetylated film in a hexane solution of acyl chloride, react for a preset time to obtain a cross-linked film of acyl chloride, remove the cross-linked film of acyl chloride, wash with deionized water and dry.

[0034] S4: Prepare aqueous solutions of silane coupling agent of different concentrations using silane coupling agent. Immerse the dried acyl chloride crosslinked membrane in the aqueous solution of silane coupling agent, adjust the pH, and after the silane coupling agent has undergone hydrolysis reaction for a preset time, remove it and air dry it to obtain an oil-water separation membrane.

[0035] S5: Use the prepared oil-water separation membrane for oil-water separation and evaluate the membrane's permeability and separation performance.

[0036] The mass ratio of cellulose acetate to cellulose nitrate in S1 is 1:0 to 0:1; preferably, the mass ratio of cellulose acetate to cellulose nitrate in S1 is 1:1.

[0037] The non-solvent phase in S1 is one of deionized water, methanol, ethanol, ethylene glycol, diethylene glycol, isopropanol, or tetrachloroethylene; preferably, the non-solvent phase in S1 is deionized water, ethanol, or methanol.

[0038] The solute in the alkaline solution described in S2 is one of lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, sodium carbonate, or potassium carbonate; preferably, the alkaline solution described in S2 is an aqueous solution of sodium hydroxide or an aqueous solution of potassium hydroxide.

[0039] The film described in S2 is immersed in an alkaline solution for a preset time of 1 min to 25 h; preferably, the immersion time in the alkaline solution in S2 is 3 h.

[0040] The concentration of the alkaline solution in S2 is 0.01 ~ 0.2 mol / L, preferably 0.05 mol / L.

[0041] The acyl chloride in S3 is one of 1,3,5-benzenetricarboxyl chloride, terephthaloyl chloride, orthophthaloyl chloride, isophthaloyl chloride, octanoyl chloride, adipyl chloride, glutaryl chloride, sebacyl chloride, azeloyl chloride, methylmalonyl chloride, 1,7-heptanoyl chloride, 2,6-naphthalenedilicate chloride, 2,5-furandicarboxyl chloride, hexafluoroglutaryl chloride, tetrafluorosuccinyl chloride, octafluoroadipyl chloride, 3-methyladipyl chloride, or 1,4-benzenediacryl chloride; preferably, the acyl chloride in S3 is 1,3,5-benzenetricarboxyl chloride.

[0042] The concentration of the acyl chloride in S3 is 0.005 mol / L to 0.02 mol / L; preferably, the concentration of the acyl chloride in S3 is 0.01 mol / L.

[0043] The silane coupling agent in S4 is one of dodecyltrimethoxysilane, dodecyltriethoxysilane, hexadecyltrimethoxysilane, hexadecyltriethoxysilane, octadecyltrimethoxysilane, octadecyltriethoxysilane, octadecyldimethylmethoxysilane, octyltrimethoxysilane, n-octyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(β-methoxyethoxy)silane, methacryloxysilane, isobutyltriethoxysilane, butyldimethylchlorosilane, butyltriethoxysilane, pentyltriethoxysilane, isobutyltriethoxysilane, hexyltriethoxysilane, methyltriacetoxysilane, octylmethyldimethoxysilane, propyltrimethoxysilane, or hexyltrimethoxysilane; preferably, the silane coupling agent in S4 is n-octyltrimethoxysilane.

[0044] The aqueous solution of the silane coupling agent in S4 has a mass concentration of 0.01 g / L to 10 g / L; preferably, the aqueous solution of the silane coupling agent in S4 has a mass concentration of 1.5 g / L.

[0045] The hydrolysis time of the silane coupling agent in S4 is 0~48 h; preferably, the hydrolysis time of the silane coupling agent is 1 h.

[0046] The pH of the aqueous solution of the silane coupling agent in S4 is 3 to 13, preferably 4 to 5.

[0047] Example 1

[0048] Step 1: Mix cellulose acetate and cellulose nitrate powders at a mass ratio of 1:1 and dissolve them in N-methylpyrrolidone to form a uniform casting solution; after removing air bubbles from the casting solution, pour it onto a glass plate and coat it into a film, then immediately immerse it in deionized water to precipitate; after complete solidification, peel off the prepared film and wash it in deionized water.

[0049] Step 2: Immerse the washed film in a 0.05 mol / L sodium hydroxide aqueous solution, let it stand for 3 hours to obtain a deacetylated film, take it out, wash it with deionized water, and dry it.

[0050] Step 3: The dried deacetylated membrane is directly immersed in a 0.005 mol / L hexane solution of 1,3,5-benzenetricarboxylic acid chloride. After reacting for a certain period of time, an acyl chloride cross-linked membrane is obtained. The acyl chloride cross-linked membrane is then removed, washed with deionized water, and dried.

[0051] Step 4: Prepare an aqueous solution of n-octyltrimethoxysilane with a concentration of 1.5 g / L, immerse the dried acyl chloride crosslinked membrane in the solution, adjust the pH to 4.0, and after the silane coupling agent has been hydrolyzed for 20 minutes, remove it and air dry to obtain the oil-water separation membrane.

[0052] S5: Use the prepared oil-water separation membrane for oil-water separation and evaluate the membrane's permeability and separation performance.

[0053] Example 2

[0054] Step 1: Mix cellulose acetate and cellulose nitrate powders at a mass ratio of 1:1 and dissolve them in N-methylpyrrolidone to form a uniform casting solution; after removing air bubbles from the casting solution, pour it onto a glass plate and coat it into a film, then immediately immerse it in deionized water to precipitate; after complete solidification, peel off the prepared film and wash it in deionized water.

[0055] Step 2: Immerse the washed film in a 0.05 mol / L sodium hydroxide aqueous solution, let it stand for 3 hours to obtain a deacetylated film, take it out, wash it with deionized water, and dry it.

[0056] Step 3: The dried deacetylated membrane is directly immersed in a 0.01 mol / L hexane solution of 1,3,5-benzenetricarboxylic acid chloride. After reacting for a certain time, it is washed with water to obtain a cross-linked membrane of acyl chloride. The cross-linked membrane of acyl chloride is then taken out, washed with deionized water, and dried.

[0057] Step 4: Prepare an aqueous solution of n-octyltrimethoxysilane with a concentration of 1.5 g / L, immerse the dried acyl chloride crosslinked membrane in the solution, adjust the pH to 4.0, and after the silane coupling agent has been hydrolyzed for 20 minutes, remove it and air dry to obtain the oil-water separation membrane.

[0058] S5: Use the prepared oil-water separation membrane for oil-water separation and evaluate the membrane's permeability and separation performance.

[0059] Example 3

[0060] Step 1: Mix cellulose acetate and cellulose nitrate powders at a mass ratio of 1:1 and dissolve them in N-methylpyrrolidone to form a uniform casting solution; after removing air bubbles from the casting solution, pour it onto a glass plate and coat it into a film, then immediately immerse it in deionized water to precipitate; after complete solidification, peel off the prepared film and wash it in deionized water.

[0061] Step 2: Immerse the washed film in a 0.05 mol / L sodium hydroxide aqueous solution, let it stand for 3 hours to obtain a deacetylated film, take it out, wash it with deionized water and dry it.

[0062] Step 3: The dried deacetylated membrane is directly immersed in a 0.015 mol / L hexane solution of 1,3,5-benzenetricarboxylic acid chloride. After reacting for a certain time, it is washed with water to obtain a cross-linked membrane of acyl chloride. The cross-linked membrane of acyl chloride is then taken out, washed with deionized water, and dried.

[0063] Step 4: Prepare an aqueous solution of n-octyltrimethoxysilane with a concentration of 1.5 g / L, immerse the dried acyl chloride crosslinked membrane in the solution, adjust the pH to 4.0, and after the silane coupling agent has been hydrolyzed for 20 minutes, remove it and air dry to obtain the oil-water separation membrane.

[0064] S5: Use the prepared oil-water separation membrane for oil-water separation and evaluate the membrane's permeability and separation performance.

[0065] Example 4

[0066] Step 1: Mix cellulose acetate and cellulose nitrate powders at a mass ratio of 1:1 and dissolve them in N-methylpyrrolidone to form a uniform casting solution; after removing air bubbles from the casting solution, pour it onto a glass plate and coat it into a film, then immediately immerse it in deionized water to precipitate; after complete solidification, peel off the prepared film and wash it in deionized water.

[0067] Step 2: Immerse the washed film in a 0.05 mol / L sodium hydroxide aqueous solution, let it stand for 3 hours to obtain a deacetylated film, take it out, wash it with deionized water and dry it.

[0068] Step 3: The dried deacetylated membrane is directly immersed in a 0.02 mol / L hexane solution of 1,3,5-benzenetricarboxylic acid chloride. After reacting for a certain time, it is washed with water to obtain a cross-linked membrane of acyl chloride. The cross-linked membrane of acyl chloride is then taken out, washed with deionized water, and dried.

[0069] Step 4: Prepare an aqueous solution of n-octyltrimethoxysilane with a concentration of 1.5 g / L, immerse the dried acyl chloride crosslinked membrane in the solution, adjust the pH to 4.0, and after the silane coupling agent has been hydrolyzed for 20 minutes, remove it and air dry to obtain the oil-water separation membrane.

[0070] S5: Use the prepared oil-water separation membrane for oil-water separation and evaluate the membrane's permeability and separation performance.

[0071] Example 5

[0072] Step 1: Mix cellulose acetate and cellulose nitrate powders at a mass ratio of 1:1 and dissolve them in N-methylpyrrolidone to form a uniform casting solution; after removing air bubbles from the casting solution, pour it onto a glass plate and coat it into a film, then immediately immerse it in deionized water to precipitate; after complete solidification, peel off the prepared film and wash it in deionized water.

[0073] Step 2: Immerse the washed film in a 0.05 mol / L sodium hydroxide aqueous solution, let it stand for 3 hours to obtain a deacetylated film, take it out, wash it with deionized water, and dry it.

[0074] Step 3: The dried deacetylated membrane is directly immersed in a 0.01 mol / L hexane solution of 1,3,5-benzenetricarboxylic acid chloride. After reacting for a certain time, it is washed with water to obtain a cross-linked membrane of acyl chloride. The cross-linked membrane of acyl chloride is then taken out, washed with deionized water, and dried.

[0075] Step 4: Prepare an aqueous solution of n-octyltrimethoxysilane with a concentration of 1.5 g / L, immerse the dried acyl chloride crosslinked membrane in the solution, adjust the pH to 4.0, and after the silane coupling agent has been hydrolyzed for 30 minutes, remove it and air dry to obtain the oil-water separation membrane.

[0076] S5: Use the prepared oil-water separation membrane for oil-water separation and evaluate the membrane's permeability and separation performance.

[0077] Example 6

[0078] Step 1: Mix cellulose acetate and cellulose nitrate powders at a mass ratio of 1:1 and dissolve them in N-methylpyrrolidone to form a uniform casting solution; after removing air bubbles from the casting solution, pour it onto a glass plate and coat it into a film, then immediately immerse it in deionized water to precipitate; after complete solidification, peel off the prepared film and wash it in deionized water.

[0079] Step 2: Immerse the washed film in a 0.05 mol / L sodium hydroxide aqueous solution, let it stand for 3 hours to obtain a deacetylated film, take it out, wash it with deionized water, and dry it.

[0080] Step 3: The dried deacetylated membrane is directly immersed in a 0.01 mol / L hexane solution of 1,3,5-benzenetricarboxylic acid chloride. After reacting for a certain time, it is washed with water to obtain a cross-linked membrane of acyl chloride. The cross-linked membrane of acyl chloride is then taken out, washed with deionized water, and dried.

[0081] Step 4: Prepare an aqueous solution of n-octyltrimethoxysilane with a concentration of 1.5 g / L, immerse the dried acyl chloride crosslinked membrane in the solution, adjust the pH to 4.0, and after the silane coupling agent has been hydrolyzed for 45 minutes, remove it and air dry to obtain the oil-water separation membrane.

[0082] S5: Use the prepared oil-water separation membrane for oil-water separation and evaluate the membrane's permeability and separation performance.

[0083] Example 7

[0084] Step 1: Mix cellulose acetate and cellulose nitrate powders at a mass ratio of 1:1 and dissolve them in N-methylpyrrolidone to form a uniform casting solution; after removing air bubbles from the casting solution, pour it onto a glass plate and coat it into a film, then immediately immerse it in deionized water to precipitate; after complete solidification, peel off the prepared film and wash it in deionized water.

[0085] Step 2: Immerse the washed film in a 0.05 mol / L sodium hydroxide aqueous solution, let it stand for 3 hours to obtain a deacetylated film, take it out, wash it with deionized water, and dry it.

[0086] Step 3: The dried deacetylated membrane is directly immersed in a 0.01 mol / L hexane solution of 1,3,5-benzenetricarboxylic acid chloride. After reacting for a certain time, it is washed with water to obtain a cross-linked membrane of acyl chloride. The cross-linked membrane of acyl chloride is then taken out, washed with deionized water, and dried.

[0087] Step 4: Prepare an aqueous solution of n-octyltrimethoxysilane with a concentration of 1.5 g / L, immerse the dried acyl chloride crosslinked membrane in the solution, adjust the pH to 4.0, and after the silane coupling agent has been hydrolyzed for 60 minutes, remove it and air dry to obtain the oil-water separation membrane.

[0088] S5: Use the prepared oil-water separation membrane for oil-water separation and evaluate the membrane's permeability and separation performance.

[0089] Example 8

[0090] Step 1: Mix cellulose acetate and cellulose nitrate powders at a mass ratio of 1:1 and dissolve them in N-methylpyrrolidone to form a uniform casting solution; after removing air bubbles from the casting solution, pour it onto a glass plate and coat it into a film, then immediately immerse it in deionized water to precipitate; after complete solidification, peel off the prepared film and wash it in deionized water.

[0091] Step 2: Immerse the washed film in a 0.05 mol / L sodium hydroxide aqueous solution, let it stand for 3 hours to obtain a deacetylated film, take it out, wash it with deionized water, and dry it.

[0092] Step 3: The dried deacetylated membrane is directly immersed in a 0.01 mol / L hexane solution of 1,3,5-benzenetricarboxylic acid chloride. After reacting for a certain time, it is washed with water to obtain a cross-linked membrane of acyl chloride. The cross-linked membrane of acyl chloride is then taken out, washed with deionized water, and dried.

[0093] Step 4: Prepare an aqueous solution of n-octyltrimethoxysilane with a concentration of 1.5 g / L, immerse the dried acyl chloride crosslinked membrane in the solution, adjust the pH to 4.0, and after the silane coupling agent has been hydrolyzed for 48 h, remove it and air dry to obtain the oil-water separation membrane.

[0094] S5: Use the prepared oil-water separation membrane for oil-water separation and evaluate the membrane's permeability and separation performance.

[0095] Example 9

[0096] Step 1: Mix cellulose acetate and cellulose nitrate powders at a mass ratio of 1:1 and dissolve them in N-methylpyrrolidone to form a uniform casting solution; after removing air bubbles from the casting solution, pour it onto a glass plate and coat it into a film, then immediately immerse it in deionized water to precipitate; after complete solidification, peel off the prepared film and wash it in deionized water.

[0097] Step 2: Immerse the washed film in a 0.05 mol / L sodium hydroxide aqueous solution, let it stand for 3 hours to obtain a deacetylated film, take it out, wash it with deionized water, and dry it.

[0098] Step 3: The dried and deacetylated membrane is directly immersed in a 0.01 mol / L hexane solution of 1,3,5-benzenetricarboxylic acid chloride. After reacting for a certain time, it is washed with water to obtain a membrane cross-linked with acyl chloride. The membrane cross-linked with acyl chloride is then removed, washed with deionized water, and dried.

[0099] Step 4: Prepare an aqueous solution of n-octyltrimethoxysilane with a concentration of 0.01 g / L, immerse the dried acyl chloride crosslinked membrane in the solution, adjust the pH to 4.0, and after the silane coupling agent has been hydrolyzed for 60 min, remove it and air dry to obtain the oil-water separation membrane.

[0100] S5: Use the prepared oil-water separation membrane for oil-water separation and evaluate the membrane's permeability and separation performance.

[0101] Example 10

[0102] Step 1: Mix cellulose acetate and cellulose nitrate powders at a mass ratio of 1:1 and dissolve them in N-methylpyrrolidone to form a uniform casting solution; after removing air bubbles from the casting solution, pour it onto a glass plate and coat it into a film, then immediately immerse it in deionized water to precipitate; after complete solidification, peel off the prepared film and wash it in deionized water.

[0103] Step 2: Immerse the washed film in a 0.05 mol / L sodium hydroxide aqueous solution, let it stand for 3 hours to obtain a deacetylated film, take it out, wash it with deionized water, and dry it.

[0104] Step 3: The dried and deacetylated membrane is directly immersed in a 0.01 mol / L hexane solution of 1,3,5-benzenetricarboxylic acid chloride. After reacting for a certain time, it is washed with water to obtain a membrane cross-linked with acyl chloride. The membrane cross-linked with acyl chloride is then removed, washed with deionized water, and dried.

[0105] Step 4: Prepare an aqueous solution of n-octyltrimethoxysilane with a concentration of 10 g / L, immerse the dried acyl chloride crosslinked membrane in the solution, adjust the pH to 4.0, and after the silane coupling agent has been hydrolyzed for 60 min, remove it and air dry to obtain the oil-water separation membrane.

[0106] S5: Use the prepared oil-water separation membrane for oil-water separation and evaluate the membrane's permeability and separation performance.

[0107] In Examples 1-10, the non-solvent phase can also be one of methanol, ethanol, ethylene glycol, diethylene glycol, isopropanol, or tetrachloroethylene, which has the same effect as deionized water.

[0108] In Examples 1-10, the alkaline solution can also be one of the aqueous solutions of lithium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, sodium carbonate, or potassium carbonate, which has the same effect as the aqueous solution of sodium hydroxide.

[0109] In Examples 1-10, the acyl chloride can also be one of terephthaloyl chloride, phthaloyl chloride, isophthaloyl chloride, octanoyl chloride, adipyl chloride, glutaryl chloride, sebacyl chloride, azeloyl chloride, methylmalonyl chloride, 1,7-heptanoyl chloride, 2,6-naphthalenedilicate chloride, 2,5-furandicarboxyl chloride, hexafluoroglutaryl chloride, tetrafluorosuccinyl chloride, octafluoroadipyl chloride, 3-methyladipyl chloride, or 1,4-benzenediacryl chloride, which has the same effect as 1,3,5-benzenediacryl chloride.

[0110] The silane coupling agent in Examples 1-10 can also be one of dodecyltrimethoxysilane, dodecyltriethoxysilane, hexadecyltrimethoxysilane, hexadecyltriethoxysilane, octadecyltrimethoxysilane, octadecyltriethoxysilane, octadecyldimethylmethoxysilane, octyltrimethoxysilane, n-octyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(β-methoxyethoxy)silane, methacryloxysilane, isobutyltriethoxysilane, butyldimethylchlorosilane, butyltriethoxysilane, pentyltriethoxysilane, isobutyltriethoxysilane, hexyltriethoxysilane, methyltriacetoxysilane, octylmethyldimethoxysilane, propyltrimethoxysilane, or hexyltrimethoxysilane, and has the same effect as n-octyltrimethoxysilane.

[0111] Comparative example

[0112] Step 1: Mix cellulose acetate and cellulose nitrate powders at a mass ratio of 1:1 and dissolve them in N-methylpyrrolidone to form a uniform casting solution; after removing air bubbles from the casting solution, pour it onto a glass plate and coat it into a film, then immediately immerse it in deionized water to precipitate; after complete solidification, peel off the prepared film and soak it in deionized water.

[0113] like Figure 1 As shown, the film prepared in Example 7 exhibits a hydrophobic state when in contact with water droplets in an oil solution.

[0114] like Figure 2 As shown in the figure, (a) is the hydrophilic and hydrophobic performance test result of the film prepared in the comparative example, and (b) is the hydrophilic and hydrophobic performance test result of the film prepared in Example 7. As can be seen from the figure, the film prepared in Example 7 exhibits good hydrophobic properties.

[0115] like Figure 3 As shown in the figure, the infrared spectra of the films prepared in Example 7 and the comparative example are shown. It can be seen from the figure that the film modified with n-octyltrimethoxysilane has a higher infrared spectrum at 2970 cm⁻¹. -1 The presence of a characteristic peak of methyl (-CH3) at the wavelength position indicates that n-octyltrimethoxysilane is attached to the surface of the membrane via in-situ hydrolysis.

[0116] like Figure 4 As shown in the figure, the TGA spectra of the films prepared in Example 7 and the comparative example are shown. As can be seen from the figure, the thermal decomposition temperature of the two films is higher than 200℃, which can meet the temperature required for oil-water separation (100℃). Moreover, the thermal properties of the cellulose acetate and cellulose nitrate mixed film are significantly improved after crosslinking and silane modification.

[0117] like Figure 5 As shown, Figure 5 (a) is a SEM image of a cellulose acetate and cellulose nitrate mixed film. As can be seen from the image, the film has long and thin fibers and exhibits a uniformly distributed macroporous structure. Figure 5 (b) is a SEM image of the film after crosslinking 1,3,5-benzenetricarboxylic acid chloride in step 3 of Example 7 of the present invention. As can be seen from the figure, the fiber connection of the film is enhanced after crosslinking. Figure 5 (c) is a SEM image of the film after in-situ hydrolysis of n-octyltrimethoxysilane in step 4 of Example 7 of the present invention. As can be seen from the figure, the surface of the film after in-situ hydrolysis of silane exhibits coarse fibrous structure.

[0118] Table 1 shows the test results of the permeation performance of Bupleurum chinense volatile oil and water rejection rate of the membranes prepared in Examples 1-10 and Comparative Examples of the present invention. As can be seen from the table, the membranes prepared by the present invention have excellent oil-water separation performance.

[0119] Table 1. Test results of oil permeability and water rejection rate of the films prepared in Examples 1-10 and Comparative Examples.

[0120]

[0121] The prepared membranes were used for the separation of oil and water from Bupleurum chinense volatile oil. The permeability and separation performance of the membranes were evaluated, and the results are shown in Table 1. As can be seen from the table, the separation membrane with a mixed matrix of cellulose acetate and cellulose nitrate, after deacetylation treatment and subsequent crosslinking with 1,3,5-benzenetricarboxylic acid chloride and modification with n-octyltrimethoxysilane, showed significantly higher oil permeability and water rejection rate than the membrane without crosslinking and silane coupling agent modification. The results indicate that the membranes prepared according to the method of this invention possess excellent oil-water separation performance.

[0122] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still make modifications or equivalent substitutions to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the protection scope of the claims of the present invention pending approval.

Claims

1. A method for preparing an oil-water separation membrane in the refining process of Bupleurum chinense volatile oil, characterized in that, Includes the following steps: Cellulose acetate and cellulose nitrate powders are mixed and dissolved according to a preset mass ratio to form a casting solution; the casting solution is coated into a film and then immersed in a non-solvent phase to precipitate a thin film; after the film solidifies, the film is washed by immersing it in deionized water. The washed membrane was immersed in an alkaline solution and reacted for a preset time to obtain a deacetylated membrane. The deacetylated membrane was then removed, washed with deionized water, and dried. The concentration of the alkaline solution is 0.01 mol / L to 0.2 mol / L, and the soaking time in the alkaline solution is 1 min to 25 h. The dried deacetylated film was immersed in a hexane solution of acyl chloride and reacted for a preset time to obtain an acyl chloride crosslinked film. The crosslinked film was then removed, washed with deionized water, and dried. The concentration of the acyl chloride was 0.005 mol / L to 0.02 mol / L. Different concentrations of silane coupling agent aqueous solutions were prepared. The dried acyl chloride crosslinked membrane was immersed in the silane coupling agent aqueous solution, the pH of the solution was adjusted, and after the silane coupling agent underwent hydrolysis reaction for a preset time, it was taken out and dried to obtain the oil-water separation membrane.

2. The method for preparing an oil-water separation membrane in the refining process of Bupleurum chinense volatile oil according to claim 1, wherein the acyl chloride is one of 1,3,5-benzenetricarboxyl chloride, terephthaloyl chloride, orthophthaloyl chloride, isophthaloyl chloride, octanoyl chloride, adipyl chloride, glutaryl chloride, sebacyl chloride, azeloyl chloride, methylmalonyl chloride, 1,7-heptanoyl chloride, 2,6-naphthalenedilicate chloride, 2,5-furandicarboxyl chloride, hexafluoroglutaryl chloride, tetrafluorosuccinyl chloride, octafluoroadipyl chloride, 3-methyladipyl chloride, or 1,4-benzenediacryl chloride.

3. The method for preparing an oil-containing water separation membrane in the refining process of Bupleurum chinense volatile oil according to claim 1, wherein the mass concentration of the silane coupling agent aqueous solution is 0.01 g / L to 10 g / L.

4. The method for preparing an oil-water separation membrane in the refining process of Bupleurum chinense volatile oil according to claim 1, wherein the hydrolysis time of the silane coupling agent is 0~48 h.

5. The method for preparing an oil-water separation membrane in the refining process of Bupleurum chinense volatile oil according to claim 1, wherein the hydrolysis pH of the silane coupling agent is 3-13.

6. The method for preparing an oil-water separation membrane in the refining process of Bupleurum chinense volatile oil according to claim 1, wherein the silane coupling agent is one of dodecyltrimethoxysilane, dodecyltriethoxysilane, hexadecyltrimethoxysilane, hexadecyltriethoxysilane, octadecyltrimethoxysilane, octadecyltriethoxysilane, octadecyldimethylmethoxysilane, octyltrimethoxysilane, n-octyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(β-methoxyethoxy)silane, methacryloxysilane, isobutyltriethoxysilane, butyldimethylchlorosilane, butyltriethoxysilane, pentyltriethoxysilane, isobutyltriethoxysilane, hexyltriethoxysilane, methyltriacetoxysilane, octylmethyldimethoxysilane, propyltrimethoxysilane, or hexyltrimethoxysilane.

7. The oil-water separation membrane prepared by the method for preparing an oil-water separation membrane in the refining process of Bupleurum chinense volatile oil according to any one of claims 1 to 6, characterized in that, Silyl groups are attached to the surface of the oil-containing water separation membrane.

8. The application of the oil-water separation membrane according to claim 7 in the oil-water separation process of Bupleurum chinense volatile oil refining.

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