A hydrophilically modified cellulose ultrafiltration membrane and a method for producing the same
Hydrophilic cellulose ultrafiltration membranes were prepared by dissolving and modifying with NMMO·H2O and oxidants, which solved the membrane fouling problem, achieved high flux and antifouling ability, and are suitable for water treatment and food industries, while simplifying the cleaning process.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- YULIN UNIV
- Filing Date
- 2026-04-29
- Publication Date
- 2026-06-05
AI Technical Summary
Existing ultrafiltration membranes are susceptible to fouling when treating oily wastewater, leading to increased filtration resistance and flux reduction. Furthermore, traditional hydrophobic membrane materials require frequent and costly cleaning, and cellulose acetate has poor acid and alkali resistance, limiting its application.
Cellulose was dissolved using NMMO·H2O, and combined with oxidants and modifiers to prepare hydrophilic modified cellulose ultrafiltration membranes. Flat sheet or hollow fiber membranes were prepared by immersion gel phase inversion method to improve the hydrophilicity and antifouling ability of the membranes.
The prepared hydrophilic modified cellulose ultrafiltration membrane exhibits high flux and strong antifouling ability in liquid separation, making it suitable for water treatment and food processing. The process is also environmentally friendly, and high flow can be restored with simple rinsing after use.
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Abstract
Description
Technical Field
[0001] The invention relates to the field of polymer ultrafiltration membrane technology, and in particular to a hydrophilic modified cellulose ultrafiltration membrane and its preparation method. Background Technology
[0002] Oily wastewater has a wide range of sources and complex properties, causing serious pollution to the ecological environment. It must be treated to meet standards before it can be discharged. Traditional oil-water separation technologies include oil separation, flotation, flocculation, and filtration. These technologies consume a lot of energy and require the addition of chemical agents, generating a large amount of sludge. In contrast, ultrafiltration membrane separation technology is a physical method that does not require external agents. The treatment process is simple and can remove difficult-to-treat emulsified and dissolved oils, making it an ideal oil-water separation technology.
[0003] In practical applications, ultrafiltration membranes suffer from increasing filtration resistance and severely reduced filtration flux due to membrane fouling, hindering the application and promotion of this technology. Currently, most organic ultrafiltration membranes use hydrophobic materials, which easily cause serious membrane fouling, and require frequent and costly cleaning. Therefore, it is necessary to develop antifouling ultrafiltration membranes using highly hydrophilic membrane materials.
[0004] Cellulose acetate is a commonly used hydrophilic material. In liquid separation, cellulose acetate has long been considered a membrane material with great development potential due to its excellent hydrophilicity and good fouling resistance. However, compared with cellulose, cellulose acetate has poor acid and alkali resistance, poor temperature resistance, and is easily hydrolyzed, which limits its application range.
[0005] Cellulose is the most stable component of plant fibers, the most abundant natural polymer material, and a renewable green organic resource. It has excellent acid and alkali resistance. In the past, it was mostly prepared by chemical methods to obtain cellulose xanthate or copper amine complex, and then regenerated with solvent to obtain soluble regenerated cellulose. However, the ordered hydrogen bond structure in the cellulose molecule results in strong crystallinity, and the flux of the separation membrane is much lower than that of traditional polysulfone, polyvinylidene fluoride and other ultrafiltration membranes. Summary of the Invention
[0006] To address the problems mentioned in the background art, this invention provides a highly hydrophilic, high-flux, and antifouling ultrafiltration membrane. The technical solution is as follows: A method for preparing a hydrophilic modified cellulose ultrafiltration membrane includes the following steps: S1: Under nitrogen protection, cellulose is dissolved in NMMO·H2O (N-methylmorpholine-N-oxide monohydrate) with a content of 80-95 wt%, stirred at a constant temperature, and degassed under vacuum to prepare a transparent casting solution with a cellulose content of 5-20 wt%. S2: Add an oxidant to the transparent casting solution and react to obtain an aldehyde-modified cellulose solution; S3: Add a modifier to an aldehyde-modified cellulose solution and react to obtain a modified cellulose solution; S4: Add film-forming additives to the modified cellulose solution, and obtain a stable film-forming solution after vacuum degassing; S5: The immersion gel phase inversion method is adopted, and the membrane preparation solution is scraped into a flat sheet membrane by a scraper or spun into a hollow fiber membrane by a spinneret.
[0007] Furthermore, the oxidant mentioned in S2 is at least one of potassium permanganate, sodium persulfate, potassium persulfate, sodium periodate, and potassium periodate.
[0008] Furthermore, in S2, the mass ratio of oxidant to cellulose is 0.1 to 0.5:1, and the reaction time is 1 to 24 hours.
[0009] Furthermore, the modifier in S3 is at least one of terminal amine polyethylene glycol compounds, polyethyleneimine, and chitosan.
[0010] Furthermore, in S3, the mass ratio of modifier to cellulose is 0.1 to 0.5:1, and the reaction time is 1 to 24 hours.
[0011] Furthermore, the film-forming additive mentioned in S4 is at least one of ethylene glycol, ethanol, polyethylene glycol, polyvinylpyrrolidone, lithium chloride, and lithium nitrate.
[0012] Furthermore, the mass ratio of film-forming additives to cellulose in S4 is 0.01 to 0.2:1.
[0013] Furthermore, the reaction temperature in S1 to S4 is 70 to 115°C.
[0014] The present invention also provides a hydrophilic modified cellulose ultrafiltration membrane, which is prepared by the above method. The flat sheet membrane or hollow fiber membrane has an asymmetric structure with finger-shaped pore support.
[0015] The beneficial effects of this invention are as follows: 1. This invention uses NMMO·H2O, a good solvent for cellulose. It forms hydrogen bonds with the hydroxyl groups on the cellulose molecular ring through the N and O atoms on its tertiary amine, opening the original intra- and inter-chain hydrogen bonds of cellulose, allowing cellulose to be physically dissolved. This preserves more of the natural properties of cellulose, resulting in the prepared flat sheet membrane or hollow fiber membrane exhibiting better mechanical properties and acid and alkali resistance.
[0016] 2. Modified cellulose can be prepared by oxidizing with oxidants and chemical modification techniques, which can effectively reduce the crystallinity of cellulose membranes and improve their hydrophilicity, thereby increasing both the water flux and the antifouling ability of cellulose membranes.
[0017] 3. The membrane fabrication process of this invention is simple, and the solvent NMMO·H2O is easy to recover, making it a green and environmentally friendly process.
[0018] 4. The modified cellulose ultrafiltration membrane prepared by this invention has extremely high hydrophilicity, high flux, and strong antifouling ability. It is suitable for liquid separation fields, such as water treatment, food industry, or separation of polar and non-polar liquid alcohol-ketone mixtures in pervaporation. It also has good application prospects in medical dialysis, membrane extraction, and membrane absorption. Detailed Implementation
[0019] To make the technical means, features, and effects of this invention easier to understand, the technical solutions in the embodiments of this invention are clearly and completely described below in conjunction with specific implementation methods and examples of this invention. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. Example 1:
[0020] A method for preparing a hydrophilic modified cellulose ultrafiltration membrane includes the following steps: S1: At a temperature of 95℃, under nitrogen protection, 360g of NMMO·H2O with a content of 85wt% dissolved 40g of cellulose (average degree of polymerization ≈1000) was dissolved, stirred at the temperature for 24h, and after vacuum degassing, 400g of transparent casting liquid with a cellulose content of 10wt% was prepared. S2: Keep the temperature at 95℃, add 20g of sodium periodate to 400g of 10wt% transparent casting solution, stir and react for 1h to obtain aldehyde-modified cellulose solution; S3: Keep the temperature at 95℃, add 20g of polyethyleneimine (molecular weight 1700) to 420g of aldehyde-modified cellulose solution, stir and react for 1h to obtain modified cellulose solution. S4: Add 4g of polyethylene glycol (PEG400) to 440g of modified cellulose solution, maintain the temperature at 95℃ and stir. After vacuum degassing, a stable film-forming solution is obtained. S5: The immersion gel phase inversion method is adopted, and the membrane preparation solution is scraped into a flat sheet membrane by a scraper or spun into a hollow fiber membrane by a spinneret.
[0021] The spinning conditions are as follows: Spinning temperature 80℃, dry spinning distance 70mm, core solution is deionized water, core solution flow rate 0.8mL·min -1 The gel bath was water at a temperature of 50°C. The spun hollow fiber membrane was washed in flowing deionized water for 24 hours and then placed in a 50% glycerol aqueous solution for later use.
[0022] The conditions for scraping flat sheet membranes are as follows: The film-forming solution temperature was 80℃, the doctor blade height was 200μm, the film-forming speed was 10m / min, the gel bath was water, and the water bath temperature was 50℃.
[0023] The hollow fiber membrane has a crystallinity of 32% and a pure water flux of 160.28 L·m⁻¹. -2 ·h -1 The bovine serum albumin retention rate was 30.5%, and the water contact angle of the hollow fiber membrane was 13°.
[0024] The crystallinity of the flat sheet membrane is 28%, and the pure water flux is 160.25 L·m. -2 ·h -1 The bovine serum albumin retention rate was 31.5%, and the water contact angle of the flat sheet membrane was 15°.
[0025] Oil-water separation tests were conducted using produced water from the oilfield. Before the test, the oil content in the produced water was 120 ppm, the suspended particle content was 60 ppm, and the median particle size was 3 μm.
[0026] After filtration using hollow fiber membranes, the oil content in the permeate is less than 10 ppm, the suspended particulate content is 1 ppm, the median particle size is less than 1 μm, and the water flux of the hollow fiber membrane in oily wastewater is 50 L·m. -2 ·h -1 After a simple rinse, the flow recovery rate of the hollow fiber membrane was 88%.
[0027] After filtration using a flat sheet membrane, the oil content in the permeate is less than 10 ppm, the suspended particulate content is 1 ppm, the median particle size is less than 1 μm, and the water flux of the flat sheet membrane in oily wastewater is 40 L·m. -2 ·h -1 After a simple rinse, the flow recovery rate of the flat sheet membrane was 91%.
[0028] Examples 2-5 Compared with Example 1, Examples 2-5 differ in the cellulose content of the transparent casting solution in S1, while the reaction conditions, such as the amounts of oxidant, modifier, and film-forming additives and their mass ratio to cellulose, remain unchanged. Specific data are shown in the table below: Table 1. Performance data of hollow fiber membranes or flat sheet membranes prepared by transparent casting solutions with different cellulose concentrations.
[0029] The hollow fiber membranes and flat sheet membranes prepared in Examples 1-5 have small water contact angles, strong hydrophilicity, high oil removal rates, and high water flux in oily wastewater. Furthermore, after use, the flow recovery rate can be maintained at a high level through simple rinsing. Example 6
[0030] A method for preparing a modified cellulose ultrafiltration membrane includes the following steps: S1: At a temperature of 70℃, under nitrogen protection, 30g of cellulose (average degree of polymerization ≈1000) was dissolved in 370g of NMMO·H2O with a content of 95wt%. The mixture was kept warm and stirred for 48h. After vacuum degassing, 400g of transparent casting liquid with a cellulose content of 7.5wt% was prepared. S2: Keep the temperature at 70℃, add 7.5g of potassium permanganate to 400g of 7.5wt% transparent casting solution, stir and react for 10h to obtain aldehyde-modified cellulose solution; S3: Keep the temperature at 70℃, add 7.5g of chitosan to 407.5g of aldehyde-modified cellulose solution, stir and react for 10h to obtain modified cellulose solution; S4: Add 1.5g of polyvinylpyrrolidone (PVPK30) to 415g of modified cellulose solution, maintain the temperature at 70℃ and stir, and obtain a stable film-forming solution after vacuum degassing. S5: The immersion gel phase inversion method is adopted, and the membrane preparation solution is scraped into a flat sheet membrane by a scraper or spun into a hollow fiber membrane by a spinneret.
[0031] The spinning conditions are as follows: Spinning temperature 90℃, dry spinning distance 50mm, core solution is deionized water, core solution flow rate 0.8mL·min -1 The gel bath is water, and the water bath temperature is 50℃. The spun hollow fiber membrane is washed in flowing deionized water for 24 hours and then placed in a 50% glycerol aqueous solution for later use.
[0032] The conditions for scraping flat sheet membranes are as follows: The film-forming solution temperature was 80℃, the doctor blade height was 150μm, the film-forming speed was 8m / min, the gel bath was water, and the water bath temperature was 50℃.
[0033] The hollow fiber membrane has a crystallinity of 36% and a pure water flux of 130.28 L·m⁻¹. -2 ·h -1 The bovine serum albumin retention rate was 40.5%, and the water contact angle of the hollow fiber membrane was 15°.
[0034] The crystallinity of the flat sheet membrane is 32%, and the pure water flux is 150.25 L·m. -2 ·h -1 The bovine serum albumin rejection rate was 40.5%, and the water contact angle of the flat sheet membrane was 17°.
[0035] Oil-water separation tests were conducted using produced water from the oilfield. Before the test, the oil content in the produced water was 120 ppm, the suspended particle content was 60 ppm, and the median particle size was 3 μm.
[0036] After filtration using a hollow fiber membrane, the oil content in the permeate is less than 10 ppm, the suspended particulate content is 1 ppm, and the median particle size is less than 1 μm. The water flux of the separation membrane in oily wastewater is 50 L·m⁻¹. -2 ·h -1 After a simple rinse, the flow rate of the separation membrane recovered to 90%.
[0037] After filtration using a flat-sheet membrane, the oil content in the permeate was less than 10 ppm, the suspended particulate content was 1 ppm, and the median particle size was less than 1 μm. The water flux of the separation membrane in oily wastewater was 55 L·m⁻¹. -2 ·h -1 After a simple rinse, the flow rate of the separation membrane recovered to 90%.
[0038] Examples 7-10 Compared with Example 6, Examples 7-10 differ in the type and amount of oxidant in S2, while other conditions such as cellulose content, modifier, and the mass ratio of film-forming additives to cellulose remain unchanged. Specific data are shown in the table below: Table 2 Performance data of hollow fiber membranes or flat sheet membranes prepared with different oxidants and dosages
[0039] The hollow fiber membranes and flat sheet membranes prepared in Examples 6-10 have small water contact angles, strong hydrophilicity, high oil removal rates, and high water flux in oily wastewater. Furthermore, after use, the flow recovery rate can be maintained at a high level after simple rinsing. Example 11
[0040] A method for preparing a modified cellulose ultrafiltration membrane includes the following steps: S1: At a temperature of 115℃, under nitrogen protection, 60g of cellulose (average degree of polymerization ≈1000) was dissolved in 340g of NMMO·H2O with a content of 80wt%. The mixture was kept at this temperature and stirred for 12h. After vacuum degassing, 400g of transparent casting liquid with a cellulose content of 15wt% was prepared. S2: Keep the temperature at 115℃, add 6g of potassium persulfate to 400g of 15wt% transparent casting solution, stir and react for 24h to obtain aldehyde-modified cellulose solution. S3: Keep the temperature at 115℃, add 6g of polyethylene glycol diamine (molecular weight 5000) to 406g of aldehyde-modified cellulose solution, and stir for 24h to obtain modified cellulose solution. S4: Add 0.6g of lithium chloride to 412g of modified cellulose solution, maintain the temperature at 115℃ and stir, and obtain a stable film-forming solution after vacuum degassing; S5: The immersion gel phase inversion method is adopted, and the membrane preparation solution is scraped into a flat sheet membrane by a scraper or spun into a hollow fiber membrane by a spinneret.
[0041] The spinning conditions are as follows: Spinning temperature 80℃, dry spinning distance 20mm, core solution is deionized water, core solution flow rate 0.8mL·min -1 The gel bath is water, and the water bath temperature is 50℃. The spun hollow fiber membrane is washed in flowing deionized water for 24 hours and then placed in a 50% glycerol aqueous solution for later use.
[0042] The conditions for scraping flat sheet membranes are as follows: The film-forming solution temperature was 80℃, the doctor blade height was 120μm, the film-forming speed was 8m / min, the gel bath was water, and the water bath temperature was 50℃.
[0043] The hollow fiber membrane has a crystallinity of 42% and a pure water flux of 90.18 L·m⁻¹. -2 ·h -1 The bovine serum albumin retention rate was 80.5%, and the water contact angle of the hollow fiber membrane was 18°.
[0044] The crystallinity of the flat sheet membrane is 36%, and the pure water flux is 100.25 L·m. -2 ·h -1 The bovine serum albumin retention rate was 78.5%, and the water contact angle of the flat sheet membrane was 17°.
[0045] Oil-water separation tests were conducted using produced water from the oilfield. Before the test, the oil content in the produced water was 120 ppm, the suspended particle content was 60 ppm, and the median particle size was 3 μm.
[0046] After filtration using a hollow fiber membrane, the oil content in the permeate was less than 5 ppm, the suspended particulate content was 0.5 ppm, and the median particle size was less than 1 μm. The water flux of the separation membrane in oily wastewater was 40 L·m⁻¹. -2 ·h -1 After a simple rinse, the flow rate of the separation membrane recovered to 95%.
[0047] After filtration using a flat-sheet membrane, the oil content in the permeate was less than 5 ppm, the suspended particulate content was 0.5 ppm, and the median particle size was less than 1 μm. The water flux of the separation membrane in oily wastewater was 35 L·m⁻¹. -2 ·h -1 After simple rinsing, the flow recovery rate of the separation membrane was 94%.
[0048] Examples 12-15 Compared with Example 11, Examples 12-15 differ in the type and amount of film-forming additives used in S4, while other conditions such as cellulose content, the amount of oxidant and modifier, and the mass ratio of cellulose remain unchanged. Specific data are shown in the table below: Table 3 Performance data of hollow fiber membranes or flat sheet membranes prepared with different film-forming additives and dosages
[0049] The hollow fiber membranes and flat sheet membranes prepared in Examples 11-15 have small water contact angles, strong hydrophilicity, high oil removal rates, and high water flux in oily wastewater. Furthermore, after use, the flow recovery rate can be maintained at a high level through simple rinsing.
[0050] Comparative Example 1 32g of cellulose (average degree of polymerization ≈1000), 0.16g of propyl gallate, and 16g of polyethylene glycol PEG400 were added to 352g of NMMO·H2O and stirred at 95℃ under nitrogen protection for 24h until completely dissolved. After vacuum degassing, a casting solution with a cellulose concentration of 8% was obtained, which was then placed in a spinning tank for dry and wet spinning.
[0051] The spinning conditions for hollow fiber membranes are as follows: Spinning temperature 80℃, dry spinning distance 70mm, core solution is deionized water, core solution flow rate 0.8mL·min -1 The gel bath is water, and the water bath temperature is 50℃. The spun hollow fiber membrane is washed in flowing deionized water for 24 hours and then placed in a 50% glycerol aqueous solution for later use.
[0052] The conditions for scraping flat sheet membranes are as follows: The film-forming solution temperature was 80℃, the doctor blade height was 120μm, the film-forming speed was 8m / min, the gel bath was water, and the water bath temperature was 50℃.
[0053] The unmodified cellulose hollow fiber membrane has a crystallinity of 65% and a pure water flux of 27.68 L·m⁻¹. -2 ·h -1 The bovine serum albumin retention rate was 42.5%, and the water contact angle was 75°.
[0054] The unmodified cellulose flat sheet membrane has a crystallinity of 57% and a pure water flux of 22.38 L·m⁻¹. -2 ·h -1 The bovine serum albumin retention rate was 46.5%, and the water contact angle was 74°.
[0055] Oil-water separation tests were conducted using produced water from the oilfield. Before the test, the oil content in the produced water was 120 ppm, the suspended particle content was 60 ppm, and the median particle size was 3 μm.
[0056] After filtration using an unmodified cellulose hollow fiber membrane, the oil content in the permeate was less than 10 ppm, the suspended particulate content was 1 ppm, and the median particle size was less than 1 μm. The water flux of the unmodified cellulose hollow fiber membrane in oily wastewater was 14.12 L·m⁻¹. -2·h -1 After simple rinsing, the flow recovery rate of the unmodified cellulose hollow fiber membrane was 90%.
[0057] After filtration using a flat-sheet membrane, the oil content in the permeate was less than 10 ppm, the suspended particulate content was 1 ppm, and the median particle size was less than 1 μm. The water flux of the separation membrane in oily wastewater was 12.34 L·m⁻¹. -2 ·h -1 After simple rinsing, the flow recovery rate of the separation membrane was 91%.
[0058] Comparative Example 2 36g of polyvinylidene fluoride (PVDF), 12g of polyethylene glycol (PEG400), and 152g of dimethylacetamide were stirred at 80℃ under nitrogen protection for 24 hours until completely dissolved. After vacuum degassing, a PVDF casting solution was obtained and placed in a spinning tank for dry-wet spinning. The dry spinning distance was 200mm, the spinning temperature was 80℃, the core solution was deionized water, and the flow rate was 1mL·min. -1 The gel bath was water at a temperature of 20°C. The spun polyvinylidene fluoride hollow fiber membrane was washed in flowing deionized water for 24 hours and then placed in a 50% glycerol aqueous solution for later use.
[0059] The pure water flux of the polyvinylidene fluoride hollow fiber membrane was characterized to be 170 L·m. -2 ·h -1 The bovine serum albumin retention rate was 61%, and the water contact angle was 80°.
[0060] Oil-water separation tests were conducted using produced water from the oilfield. Before the test, the oil content in the produced water was 120 ppm, the suspended particle content was 60 ppm, and the median particle size was 3 μm.
[0061] After filtration through a polyvinylidene fluoride (PVDF) hollow fiber membrane, the oil content in the permeate is less than 10 ppm, the suspended particulate content is 1 ppm, and the median particle size is less than 1 μm. The water flux of the PVDF hollow fiber membrane in oily wastewater is 30 L·m⁻¹. -2 ·h -1 After simple rinsing, the flow recovery rate of the separation membrane was 30%.
[0062] Comparing the data from Examples 1-15 with those from Comparative Examples 1 and 2, the water contact angles of the hollow fiber membranes and flat sheet membranes prepared in Examples 1-15 are much smaller than those in Comparative Examples 1 and 2, indicating that the hydrophilicity of the hollow fiber membranes and flat sheet membranes prepared in Examples 1-15 is far superior to that of Comparative Examples 1 and 2. With comparable oil removal rates and flow recovery rates after rinsing, the water flux of the hollow fiber membranes and flat sheet membranes prepared in Examples 1-15 in oily wastewater is approximately three times that of Comparative Example 1, equivalent to a three-fold increase in filtration efficiency. With roughly comparable oil removal rates and water flux in oily wastewater, the flow recovery rate of the hollow fiber membranes and flat sheet membranes prepared in Examples 1-15 after simple rinsing is approximately three times that of Comparative Example 2, significantly improving the service life of the separation membranes.
[0063] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.
Claims
1. A method for preparing a hydrophilic modified cellulose ultrafiltration membrane, characterized in that, Includes the following steps: S1: Under nitrogen protection, cellulose is dissolved in NMMO·H2O with a content of 80-95 wt%, stirred at a constant temperature, and degassed under vacuum to prepare a transparent casting solution with a cellulose content of 5-20 wt%. S2: Add an oxidant to the transparent casting solution and react to obtain an aldehyde-modified cellulose solution; S3: Add a modifier to an aldehyde-modified cellulose solution and react to obtain a modified cellulose solution; S4: Add film-forming additives to the modified cellulose solution, and obtain a stable film-forming solution after vacuum degassing; S5: The immersion gel phase inversion method is adopted, and the membrane preparation solution is scraped into a flat sheet membrane by a scraper or spun into a hollow fiber membrane by a spinneret.
2. The method for preparing the hydrophilic modified cellulose ultrafiltration membrane as described in claim 1, characterized in that, The oxidant mentioned in S2 is at least one of potassium permanganate, sodium persulfate, potassium persulfate, sodium periodate, and potassium periodate.
3. The method for preparing the hydrophilic modified cellulose ultrafiltration membrane as described in claim 1, characterized in that, In S2, the mass ratio of oxidant to cellulose is 0.1 to 0.5:1, and the reaction time is 1 to 24 hours.
4. The method for preparing the hydrophilic modified cellulose ultrafiltration membrane as described in claim 1, characterized in that, The modifier in S3 is at least one of terminal amine polyethylene glycol compounds, polyethyleneimine, and chitosan.
5. The method for preparing the hydrophilic modified cellulose ultrafiltration membrane as described in claim 1, characterized in that, In S3, the mass ratio of modifier to cellulose is 0.1 to 0.5:1, and the reaction time is 1 to 24 hours.
6. The method for preparing the hydrophilic modified cellulose ultrafiltration membrane as described in claim 1, characterized in that, The film-forming additive mentioned in S4 is at least one of ethylene glycol, ethanol, polyethylene glycol, polyvinylpyrrolidone, lithium chloride, and lithium nitrate.
7. The method for preparing the hydrophilic modified cellulose ultrafiltration membrane as described in claim 1, characterized in that, The mass ratio of the film-forming additive in S4 to cellulose is 0.01 to 0.2:
1.
8. The method for preparing the hydrophilic modified cellulose ultrafiltration membrane as described in claim 1, characterized in that, The reaction temperature in S1 to S4 is 70 to 115℃.
9. A hydrophilic modified cellulose ultrafiltration membrane, characterized in that, The flat sheet membrane or hollow fiber membrane is prepared by any of the methods in claims 1 to 8, and has an asymmetric structure with finger-shaped pore support.