Microbial cellulose-based composite oil-water separation membrane

Abstract

The application discloses a kind of microbial cellulose-based composite oil-water separation membranes, belong to composite membrane field;The present application will be immersed into the plasticizing agent solution in microbial cellulose hydrogel, make plasticizing agent fully diffuse, after preliminary extrusion setting, again immersed into crosslinking agent solution, make the molecule of plasticizing agent fully crosslink in microbial cellulose hydrogel inside, prepare microbial cellulose-based composite hydrogel;After that, the oil-water separation membrane with macroscopic reticular structure is made by cutting pore channel using laser cutting technology.The contact angle of the surface of the separation membrane with water is 0 o , and the contact angle of the surface of the separation membrane with oil is 150 o underwater.The separation membrane prepared by the method of the present application is suitable for treating oil-containing wastewater mixture generated by oil pollution leakage in life, industry and sea.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of composite membranes, in particular to a microbial cellulose-based composite oil-water separation membrane. BACKGROUND

[0002] A large amount of oily wastewater is generated in daily life, oil production and chemical production processes, and it is an urgent problem to be solved to separate oil and water from the oily wastewater. The existing technologies for treating oily wastewater include distillation, standing clarification, extraction and other methods. In addition, in recent years, membrane separation technology has attracted widespread attention due to its low cost, high separation efficiency, easy operation and other advantages.

[0003] The prior art, Chinese invention patent with publication number CN113441015B discloses a microbial cellulose-agarose composite hydrogel-based oil-water separation membrane and a preparation method thereof. The prepared separation membrane is soft and easy to deform, which is not conducive to cutting out a slit. SUMMARY

[0004] The purpose of the present application is to provide a microbial cellulose-based composite oil-water separation membrane, which is prepared from microbial cellulose hydrogel and can separate oil and water.

[0005] The present application adopts the following technical solutions: The present application provides a microbial cellulose-based composite oil-water separation membrane, which is prepared by the following method: soaking sheet-shaped microbial cellulose hydrogel in water to fully swell; then sequentially immersing in a plasticizing agent solution and a crosslinking agent solution; and finally opening through holes on the membrane to obtain the microbial cellulose-based composite oil-water separation membrane.

[0006] Further, after soaking the sheet-shaped microbial cellulose hydrogel in water, an alkali solution is used for boiling.

[0007] Further, the alkali solution is any one of sodium hydroxide, potassium hydroxide and calcium hydroxide.

[0008] Further, the plasticizing agent is a high-molecular polysaccharide containing a hydroxyl group.

[0009] Further, the plasticizing agent is any one of sodium alginate, chitosan and prolamine.

[0010] Further, the crosslinking agent solution is an aqueous solution containing any one of Ca2+, Mg2+ and Cu2+ divalent cations.

[0011] Further, after immersing in the plasticizing agent solution and before immersing in the crosslinking agent solution, the plasticizing agent adhering to the surface of the hydrogel is scraped off, and the hydrogel is squeezed to have a thickness close to that of the initial sheet-shaped microbial cellulose hydrogel.

[0012] Further, the microbe cellulose-based composite oil-water separation membrane is prepared by using laser cutting technology to open holes on the membrane.

[0013] Further, the microbe cellulose-based composite oil-water separation membrane is prepared by using laser cutting technology to open holes on the membrane.

[0014] The microbe cellulose-based composite oil-water separation membrane prepared by the method has the advantages that: the microbe cellulose hydrogel is soaked in a plasticizing agent solution, so that the plasticizing agent is fully diffused, and the microbe cellulose hydrogel is preliminarily extruded and shaped, and then soaked in a crosslinking agent solution, so that the plasticizing agent molecules are fully crosslinked inside the microbe cellulose hydrogel, and the microbe cellulose-based composite hydrogel is prepared; then, a pore channel is cut by using laser cutting technology, and the microbe cellulose-based composite hydrogel is made into an oil-water separation membrane with a macroscopic reticular structure. In the air, the contact angle between the surface of the separation membrane and water is 0°, and under water, the contact angle between the surface of the separation membrane and oil is 150°. The separation membrane prepared by the method is suitable for treating oil-containing wastewater mixtures generated by oil pollution leakage in life, industry and at sea. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 A microbe cellulose hydrogel piece after being soaked in water.

[0016] Figure 2 A microbe cellulose hydrogel piece without being soaked in a plasticizing agent and a crosslinking agent.

[0017] Figure 3 A microbe cellulose hydrogel piece soaked in a plasticizing agent and a crosslinking agent.

[0018] Figure 4 A structure schematic diagram of a microbe cellulose-based composite oil-water separation membrane prepared by laser cutting.

[0019] Figure 5 A sample diagram of a microbe cellulose-based composite oil-water separation membrane prepared by the application.

[0020] Figure 6 An optical microscope diagram of Figure 5 .

[0021] Figure 7 An electron microscope diagram of Figure 5 .

[0022] Figure 8 An electron microscope diagram of a microbe cellulose hydrogel.

[0023] Figure 9 A separation membrane prepared by Comparative Example 1. EMBODIMENT

[0024] The technical solutions of the present application are described in detail below through specific examples, but the content of the present application is not limited to the following examples. Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials, reagents, etc. used in the following examples can be obtained commercially.

[0025] The present application provides a microbial cellulose-based composite oil-water separation membrane, and a preparation method thereof, which comprises the following steps:

[0026] Step 1, immerse the sheet-shaped microbial cellulose hydrogel in water to fully swell it, so that the nanometer pores inside the material are fully stretched, and the subsequent plasticizing agent molecules can easily enter the pores. Preferably, the deionized water is replaced several times during the immersion process to preliminarily wash the sugar on the surface of the hydrogel, preventing the sugar from being gelatinized due to high temperature during the subsequent alkali boiling process, and causing the microbial cellulose hydrogel sheets to stick together. The microbial cellulose hydrogel used in the present application is prepared by microbial fermentation, and has a cellulose purity of 99%, a polymerization degree of 2000-8000, a water holding capacity of 99.2-99.7%, and a nanometer pore size of 1-200 nm, and the thickness is preferably greater than 1 mm. As shown in the following figure, the microbial cellulose hydrogel sheet after water immersion is shown. Figure 1

[0027] It should be noted that the pure microbial cellulose hydrogel sheet used in the present application does not have the ability to separate oil and water, and water cannot pass through the hydrogel sheet. The reason for choosing a microbial cellulose hydrogel sheet with a thickness greater than 1 mm is that, according to tests, a separation membrane with a thickness less than 1 mm has poor pressure bearing capacity and cannot withstand the pressure of water during actual use, resulting in damage to the separation membrane.

[0028] After immersion in water, it is preferable to immerse and cook the microbial cellulose hydrogel sheet in an alkali solution with a mass fraction of 2-6% at 80-100°C in an oil bath for 4-6 hours. The alkali solution can be any alkali solution that is not easily decomposed by heat, such as sodium hydroxide, potassium hydroxide, calcium hydroxide, etc. In a specific environment, the residual microbial bacteria in the microbial cellulose hydrogel may reproduce and decompose the oil-water separation membrane. Alkali cooking can remove the residual microbial bacteria, sugars and proteins and other impurities in the hydrogel sheet, thereby avoiding this problem. In addition, the presence of alkali ions can cause the oil-water separation membrane to lose its oil-water separation ability in different acid-base environments, therefore, after alkali cooking, it is preferable to use deionized water to clean the microbial cellulose hydrogel again to remove the alkali solution ions, and clean the microbial cellulose hydrogel to a pH of 6-8. It should be noted that this step is an optional operation, and is not a necessary operation.

[0029] ​Step 2, preparation of a shaping agent solution. The shaping agent used in the present application refers to a high-molecular polysaccharide substance with good biocompatibility; specific usable shaping agents include sodium alginate, chitosan, prolamine, etc.; the shaping agent is dissolved in deionized water to prepare a solution with a mass fraction of 0.5-5%.

[0030] The mass fraction of the shaping agent in the present application determines the viscosity of the solution; the higher the mass fraction, the greater the viscosity of the solution, and the poorer the flowability of the shaping agent molecules, which will result in the difficulty of the shaping agent molecules to enter the interior of the microbial cellulose hydrogel; on the contrary, if the mass fraction is too low, there are fewer shaping agent molecules per unit volume in the solution, and more water molecules, which will result in a large proportion of water molecules and a small proportion of shaping agent molecules entering the interior of the microbial cellulose hydrogel, and poor shaping. Therefore, it has been verified through experiments that the mass fraction of the shaping agent in the shaping agent solution is preferably controlled to be 0.5-5%.

[0031] In addition, it should be pointed out that the molecular structure of the shaping agent selected in the present application contains a large number of hydroxyl groups, so that the material can have superhydrophilic and underwater superoleophobic properties; at the same time, the molecules can be crosslinked with each other under certain conditions to form a gel, which has good sol-gel properties, to make up for the problem of too soft and easy deformation of the microbial cellulose hydrogel.

[0032] Step 3, preparation of a crosslinking agent solution. The crosslinking agent used in the present application is an aqueous solution containing any one of Ca2+, Mg2+, Cu2+ and other divalent cations, which can crosslink the above-mentioned polysaccharide shaping agent molecules to form a gel. Specifically, any one of CaCl2, MgSO2, Cu(NO3)2 and other chlorides, sulfates or nitrates can be used. Specifically, the mass fraction of the crosslinking agent solution is preferably higher than 2%; if the mass fraction is too low, the crosslinking of the shaping agent molecules will not be sufficient, and the gel cannot be formed.

[0033] Step 4, preparation of a microbial cellulose-based composite hydrogel sheet.

[0034] Firstly, the microbial cellulose hydrogel treated in step 1 is immersed in the shaping agent solution prepared in step 2 for sufficient immersion, and the immersion time is preferably greater than 8h. During the immersion process, the shaping agent will diffuse into the interior of the microbial cellulose hydrogel. Due to the different viscosities caused by different concentrations of the shaping agent solution, the diffusion rate and the maximum diffusion amount of the shaping agent into the microbial cellulose hydrogel will be affected; if the immersion time is too short, the diffusion of the shaping agent molecules into the interior of the hydrogel will not be sufficient, so the immersion time is determined by the concentration and viscosity of the shaping agent solution.

[0035] Afterwards, it is preferred to further perform the following operation: taking out the microorganism cellulose hydrogel after sufficient immersion, using a scraper to remove the shaping agent adhered to the surface layer, and using a uniform-speed scraper extruder to extrude so as to make the thickness close to the thickness of the initial microorganism cellulose hydrogel sheet.

[0036] The reason for using the scraper and the extruder to extrude is as follows: the surface of the pure cellulose hydrogel sheet is uneven, and under a low-power microscope, the surface appears uneven; at the same time, the shaping agent solution has a certain viscosity, and a large amount of solution will be adhered to the surface layer of the hydrogel, which will cause the thickness of the sheet-shaped gel to increase and be uneven; if the surface is not cleaned, after subsequent immersion and crosslinking of the crosslinking agent, a sandwich structure will be formed on the upper and lower surfaces of the hydrogel sheet, which will hinder oil-water separation and greatly reduce the oil-water separation efficiency. In the present application, the extrusion ensures that the recessed surface of the microorganism cellulose hydrogel sheet does not store a large amount of shaping agent solution, and at the same time, the thickness of the composite hydrogel sheet can be accurately controlled to be uniform.

[0037] After the extrusion of the microorganism cellulose hydrogel sheet is completed, the microorganism cellulose hydrogel sheet is placed flat in a smooth glass container at the bottom, and the crosslinking agent solution prepared in step 3 is slowly and uniformly added until the solution submerges the flatly placed hydrogel sheet to form a gel; during this process, the shaping agent molecules form an interpenetrating network with the microorganism cellulose hydrogel. The immersion time is determined by the gelation rate and the gel skeleton strength, and the preferred immersion time is 10-18h. Crosslinking occurs inside the microorganism cellulose hydrogel, solving the problem of deformation due to the excessive softness of the microorganism cellulose hydrogel, and obtaining a microorganism cellulose-based composite hydrogel sheet with high mechanical strength and low deformation, which provides a favorable guarantee for the preparation of a filter membrane with stable shape and high separation efficiency. In addition, the microorganism cellulose-based composite hydrogel sheet after crosslinking has good anti-pulling ability and does not swell. As shown in FIG. 1, it is a microorganism cellulose hydrogel sheet without immersion of the shaping agent and the crosslinking agent, as shown in FIG. 2, it is a microorganism cellulose hydrogel sheet immersed with the shaping agent and the crosslinking agent. Figure 2 Figure 3

[0038] It should be noted that the hydrogel sheet after immersion in the shaping agent solution is preliminarily shaped by extrusion, and the shaping agent solution inside the hydrogel sheet has not yet formed a gel, and the shaping agent is unstable inside the hydrogel sheet. Therefore, the crosslinking agent solution is added at a relatively slow and uniform speed to reduce the impact.

[0039] Step 5: Millimeter-level through holes are opened on the microorganism cellulose-based composite hydrogel sheet prepared in step 4 to obtain a microorganism cellulose-based composite oil-water separation membrane.

[0040] ​​In a specific embodiment, laser cutting technology is used to cut several parallel slits on the two-dimensional plane of the composite hydrogel sheet at a laser power of 50-95%, with a slit width of about 0.2 mm and a cutting depth of 55-70% of the thickness of the composite hydrogel sheet. Then, the composite hydrogel sheet is rotated by 90° and cut in the perpendicular direction of the first cutting at the same laser power. Due to the cutting depth of more than 50% in both directions, a flow-through channel is formed at the intersection of the two perpendicular slits. The cross-sectional size of the flow-through channel is about 0.04 mm2. By changing the width of the cutting slit and thus the size of the flow-through channel of the separation membrane, and by changing the distance between the cutting slits to adjust the density of the flow-through channels of the separation membrane, the separation efficiency of the microbial cellulose-based composite hydrogel-based oil-water separation membrane can be regulated. As shown in Figure 4 Figure 1 is a schematic diagram of the structure of a microbial cellulose-based composite oil-water separation membrane prepared by laser cutting. Figure 5 Figure 2 is a sample diagram of a microbial cellulose-based composite oil-water separation membrane prepared. Figure 6 Figure 3 is an optical microscope image of Figure 5 Figure 4 is an optical microscope image of

[0041] Figure 7 Figure 5 is an electron microscope image of a microbial cellulose-based composite oil-water separation membrane prepared in the present application, Figure 8 Figure 6 is an electron microscope image of a microbial cellulose hydrogel. By comparison, it can be seen that the shaping agent is successfully compounded into the microbial cellulose hydrogel sheet.

[0042] Example 1

[0043] A microbial cellulose-based composite oil-water separation membrane, the preparation method comprising the following steps:

[0044] Step 1, pretreatment of microbial cellulose hydrogel: immerse the microbial cellulose hydrogel with a thickness of 1 mm in deionized water for 20 h, replace the deionized water 3 times during the immersion process, and then immerse and cook in a 2% sodium hydroxide solution at 80°C for 4 h. After alkaline cooking, wash the microbial cellulose hydrogel with deionized water to a pH of 6-8.

[0045] Step 2, preparation of shaping agent solution: dissolve 1 g of sodium alginate solid in 199 mL of deionized water to obtain a shaping agent solution with a mass fraction of 0.5%.

[0046] Step 3, preparation of crosslinking agent solution: dissolve 4 g of CaCl2 solid in 196 mL of deionized water to obtain a crosslinking agent solution with a mass fraction of 2%;

[0047] Step 4, preparation of microbial cellulose-based composite hydrogel sheet: the microbial cellulose hydrogel after step 1 treatment is immersed in the plasticizing agent solution obtained in step 2 for 8 h. After sufficient immersion, the microbial cellulose hydrogel is scraped with a spatula to remove the plasticizing agent adhered to the surface of the microbial cellulose hydrogel, and then the microbial cellulose hydrogel is extruded with a uniform-speed spatula extrusion machine until the thickness of the composite hydrogel sheet is extruded to 1.01 mm. Finally, the extruded microbial cellulose hydrogel sheet is placed flat on a smooth square glass container at the bottom, and the crosslinking agent solution prepared in step 3 is slowly and uniformly added until the solution completely submerges the flat-placed composite hydrogel sheet, and then the soaking is carried out at room temperature and normal pressure for 10 h.

[0048] Step 5, preparation of microbial cellulose-based composite oil-water separation membrane: using laser cutting technology, a slit with a pitch of 2 mm and a width of 0.03 mm is uniformly cut on the two-dimensional plane of the composite hydrogel sheet at a laser power of 50%. The cutting depth is 55-70% of the thickness of the hydrogel sheet. After cutting, the gel sheet is rotated clockwise by 90°, and the same pitch, width and depth of the slit are cut again in the vertical direction of the first cutting at the same laser power. A through hole is formed at the connection point of the two mutually perpendicular slits, and the cross-sectional size of the hole is 0.0009 mm2.

[0049] Using an oil-water separation device, the separation membrane obtained above is immersed in water, then clamped in the middle of the clamp, and the oil red dyed n-hexane and water mixture is contacted with the separation membrane through the upper feeding glass tube. The n-hexane is retained on the upper end of the separation membrane, and the water flows through the separation membrane to the lower collector, realizing the separation of the oil-water mixture. The detection shows that the separation rate is 46560 L / (m2.h), and the separation efficiency is 99.9%.

[0050] In addition, it is detected that the contact angle between the surface of the separation membrane prepared in the application and water is 0° in air, and the contact angle between the surface of the separation membrane and oil is 150° under water.

[0051] Example 2

[0052] A microbial cellulose-based composite oil-water separation membrane, the preparation method thereof comprises the following steps:

[0053] Step 1, pretreatment of microbial cellulose hydrogel: the microbial cellulose hydrogel with a thickness of 3 mm is immersed in deionized water for 24 h, and the deionized water is replaced 4 times during the immersion process. After immersion, the microbial cellulose hydrogel is immersed and cooked in a 4% sodium hydroxide solution at 80°C in an oil bath for 4 h. After alkaline cooking, the microbial cellulose hydrogel is washed again with deionized water until the pH is 6-8.

[0054] Step 2, preparation of the shaping agent solution: 2 g of sodium alginate solid was dissolved in 198 mL of deionized water, so that the mass fraction of the shaping agent solution was 1%.

[0055] Step 3, preparation of the crosslinking agent solution: 8 g of CaCl2 solid was dissolved in 192 mL of deionized water, so that the mass fraction of the crosslinking agent solution was 4%.

[0056] Step 4, preparation of the microbial cellulose-based composite hydrogel sheet: the microbial cellulose hydrogel treated in step 1 was immersed in the shaping agent solution obtained in step 2 for 10 h. Then, the microbial cellulose hydrogel after sufficient immersion was manually removed with a spatula to remove the shaping agent adhered to the surface layer of the microbial cellulose hydrogel, and then the microbial cellulose hydrogel was extruded with a uniform-speed spatula extrusion machine until the thickness of the composite hydrogel sheet was extruded to 3.02 mm. Finally, the extruded microbial cellulose hydrogel sheet was placed flat on a bottom smooth square glass container, and the crosslinking agent solution prepared in step 3 was slowly and uniformly added until the solution completely submerged the flat-placed composite hydrogel sheet, and then the soaking was carried out at room temperature and pressure for 12 h.

[0057] Step 5, preparation of the microbial cellulose-based composite oil-water separation membrane: using a laser cutting technique, a slit with a spacing of 1.5 mm and a width of 0.05 mm was uniformly cut on the two-dimensional plane of the composite hydrogel sheet at a laser power of 70%. The cutting depth was 55-70% of the thickness of the hydrogel sheet. After cutting, the gel sheet was rotated clockwise by 90o, and the same laser power was used to cut the same spacing, width and depth of the slit in the vertical direction of the first cutting. A through hole was formed at the connection point of the two mutually perpendicular slits, and the cross-sectional size of the hole was 0.0025 mm2.

[0058] Using an oil-water separation device, the above-obtained separation membrane was immersed in water and then taken out and clamped in the middle of the clamp, and various oil-water mixtures such as n-hexane, petroleum ether, vegetable oil, gasoline and diesel were tested for oil-water separation. The separation rate of the formed membrane was 46560 L / (m2.h), and the separation efficiency was 99.9%.

[0059] Example 3

[0060] A microbial cellulose-based composite oil-water separation membrane, the preparation method thereof comprises the following steps:

[0061] Step 1, pretreatment of the microbial cellulose hydrogel: the microbial cellulose hydrogel with a thickness of 10 mm was immersed in deionized water for 36 h, and the deionized water was replaced 5 times during the immersion. After immersion, a 6% sodium hydroxide solution was used to soak and cook the microbial cellulose hydrogel in an oil bath at 90oC for 6 h. After alkaline cooking, the microbial cellulose hydrogel was washed again with deionized water until the pH was 6-8.

[0062] Step 2, Preparation of plasticizer solution: Dissolve 10g of sodium alginate solid in 190mL of deionized water to make the mass fraction of plasticizer solution 5%.

[0063] Step 3, preparation of crosslinking agent solution: Dissolve 20g of CaCl2 solid in 180mL of deionized water to obtain a crosslinking agent solution with a mass fraction of 10%.

[0064] Step 4, Preparation of Microbial Cellulose-Based Composite Hydrogel Sheets: The microbial cellulose hydrogel treated in Step 1 is immersed in the plasticizer solution obtained in Step 2 for 14 hours. Afterwards, the plasticizer adhering to the surface of the fully immersed microbial cellulose hydrogel is manually removed using a scraper. Then, the microbial cellulose hydrogel is extruded using a uniform-speed scraper extruder until the composite hydrogel sheet thickness reaches 9.97 mm. Finally, the extruded microbial cellulose hydrogel sheet is laid flat in a square glass container with a smooth, flat bottom. The crosslinking agent solution prepared in Step 3 is slowly and uniformly added until the solution completely submerges the flattened composite hydrogel sheet. The container is then soaked at room temperature and pressure for 18 hours.

[0065] Step 5, Preparation of the microbial cellulose-based composite oil-water separation membrane: Using laser cutting technology, slits with a spacing of 2 mm and a width of 0.2 mm are uniformly cut on the two-dimensional plane of the composite hydrogel sheet at 95% laser power. The cutting depth is 55-70% of the thickness of the hydrogel sheet. After cutting, the hydrogel sheet is rotated 90° clockwise, and slits with the same spacing, width, and depth are repeatedly cut in the perpendicular direction of the first cut with the same laser power. A through hole is formed at the junction of two mutually perpendicular slits, with a cross-sectional size of 0.04 mm².

[0066] An experiment was conducted using an oil-water separation device. The obtained separation membrane was immersed in water and then clamped between fixtures. A mixture of edible peanut oil and water was introduced into contact with the separation membrane through the upper feed glass tube. The oil was trapped at the upper end of the membrane, while the water flowed through the membrane to the lower collector, thus achieving oil-water separation. The separation rate after membrane formation reached 47980 L / (m²·h), with a separation efficiency of 99.6%.

[0067] Comparative Example 1

[0068] The difference from Example 1 is that Comparative Example 1 was not soaked in a solution of plasticizer and crosslinking agent. Figure 9 The separation membrane shown is prepared in Comparative Example 1. It was not soaked and shaped in a solution of plasticizer and crosslinking agent. The microbial cellulose hydrogel was too soft and easily deformed, with poor mechanical strength. The slits cut by laser were of varying widths, making it impossible to separate oil and water.

[0069] The oil-water separation membrane prepared by the method of the present application is suitable for treating oil-containing wastewater mixture generated by oil pollution leakage in life, industry and sea, and can realize separation of oil-containing extraction mixture in industry, and has higher separation efficiency compared with traditional separation methods. When the oil-water separation membrane is used for separation of oil-water mixture, the separation membrane is first pre-wetted with water, and then the oil-water mixture is contacted with the separation membrane after sufficient wetting, so that the oil is retained on one side of the separation membrane, and the water permeates through the separation membrane to the other side of the separation membrane, thereby realizing separation of the oil-water mixture. It is detected that the separation membrane has good separation effect on single oil such as n-hexane, benzene and its derivatives, petroleum ether, chloroform, and mixture of various oils such as vegetable oil, animal oil, gasoline, diesel oil and petroleum.

[0070] The above examples are only examples for clearly illustrating the present application, and are not intended to limit the embodiments. Based on the above description, other different forms of changes can be made by those skilled in the art. The obvious changes derived therefrom are within the protection scope of the present application. Finally, it should be noted that the terms “comprise”, “include” or any other variants thereof are intended to cover non-exclusive inclusion, so that the processes, methods, articles or devices comprising a series of elements not only include those elements, but also include other elements not explicitly listed or inherent to such processes, methods, articles or devices.

Claims

1. A microbial cellulose-based composite oil-water separation membrane, characterized in that, The microbial cellulose hydrogel was prepared by impregnating it with water until it swelled fully; then, it was impregnated sequentially with a plasticizer solution and a crosslinking agent solution; finally, pores were opened on the membrane to obtain a microbial cellulose-based composite oil-water separation membrane; the plasticizer was any one of sodium alginate, chitosan, and prolysin; the crosslinking agent solution contained Ca 2+ Mg 2+ Cu 2+ An aqueous solution of any divalent cation.

2. The microbial cellulose-based composite oil-water separation membrane according to claim 1, characterized in that: After soaking the sheet-like microbial cellulose hydrogel in water, it was boiled in an alkaline solution.

3. The microbial cellulose-based composite oil-water separation membrane according to claim 2, characterized in that: The alkaline solution is any one of sodium hydroxide, potassium hydroxide, and calcium hydroxide.

4. The microbial cellulose-based composite oil-water separation membrane according to claim 1, characterized in that: The shaping agent is a high-molecular-weight polysaccharide containing hydroxyl groups.

5. The microbial cellulose-based composite oil-water separation membrane according to claim 1, characterized in that: After impregnation with the shaping agent solution and before impregnation with the crosslinking agent solution, the shaping agent adhering to the surface of the hydrogel is scraped off, and the surface is squeezed to make its thickness close to that of the initial microbial cellulose hydrogel sheet.

6. The microbial cellulose-based composite oil-water separation membrane according to claim 1, characterized in that: Microbial cellulose-based composite oil-water separation membranes were prepared by creating pores in the membrane using laser cutting technology.

7. The microbial cellulose-based composite oil-water separation membrane according to claim 6, characterized in that: Laser cutting technology is used to make two intersecting cuts on the membrane to form several slits. Each cut is 55-70% of the membrane thickness, and flow channels are formed at the intersection of the slits.

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