WO2023035556A1 - 正渗透膜及其制备方法 - Google Patents

正渗透膜及其制备方法 Download PDF

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WO2023035556A1
WO2023035556A1 PCT/CN2022/078220 CN2022078220W WO2023035556A1 WO 2023035556 A1 WO2023035556 A1 WO 2023035556A1 CN 2022078220 W CN2022078220 W CN 2022078220W WO 2023035556 A1 WO2023035556 A1 WO 2023035556A1
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forward osmosis
osmosis membrane
membrane
preparation
hydrophilic polymer
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French (fr)
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唐春
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北京宝盛通国际电气工程技术有限公司
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/08—Polysaccharides
    • B01D71/12—Cellulose derivatives
    • B01D71/14—Esters of organic acids
    • B01D71/16—Cellulose acetate
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0002—Organic membrane manufacture
    • B01D67/0009—Organic membrane manufacture by phase separation, sol-gel transition, evaporation or solvent quenching
    • B01D67/0013—Casting processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0002—Organic membrane manufacture
    • B01D67/0009—Organic membrane manufacture by phase separation, sol-gel transition, evaporation or solvent quenching
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0002—Organic membrane manufacture
    • B01D67/0009—Organic membrane manufacture by phase separation, sol-gel transition, evaporation or solvent quenching
    • B01D67/0011—Casting solutions therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0002—Organic membrane manufacture
    • B01D67/0009—Organic membrane manufacture by phase separation, sol-gel transition, evaporation or solvent quenching
    • B01D67/0011—Casting solutions therefor
    • B01D67/00113—Pretreatment of the casting solutions, e.g. thermal treatment or ageing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0081—After-treatment of organic or inorganic membranes
    • B01D67/0097—Storing or preservation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/02—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/10—Supported membranes; Membrane supports
    • B01D69/107—Organic support material
    • B01D69/1071—Woven, non-woven or net mesh
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/12—Composite membranes; Ultra-thin membranes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/26—Polyalkenes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/38—Polyalkenylalcohols; Polyalkenylesters; Polyalkenylethers; Polyalkenylaldehydes; Polyalkenylketones; Polyalkenylacetals; Polyalkenylketals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/40—Polymers of unsaturated acids or derivatives thereof, e.g. salts, amides, imides, nitriles, anhydrides, esters
    • B01D71/42—Polymers of nitriles, e.g. polyacrylonitrile
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/44—Polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds, not provided for in a single one of groups B01D71/26-B01D71/42
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/70—Polymers having silicon in the main chain, with or without sulfur, nitrogen, oxygen or carbon only
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/76—Macromolecular material not specifically provided for in a single one of groups B01D71/08 - B01D71/74
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/02—Hydrophilization
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/15—Use of additives
    • B01D2323/218—Additive materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/219—Specific solvent system
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/04—Characteristic thickness
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/28—Degradation or stability over time
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/30—Chemical resistance
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/36—Hydrophilic membranes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/002—Forward osmosis or direct osmosis
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A20/00—Water conservation; Efficient water supply; Efficient water use
    • Y02A20/124—Water desalination
    • Y02A20/131—Reverse-osmosis

Definitions

  • the invention relates to the technical field of polymer separation membranes and their preparation, in particular to an oxidation-resistant forward osmosis membrane and a preparation method thereof.
  • the forward osmosis (FO) process is a process in which the osmotic pressure difference between the draw solution and the raw material solution is the driving force, and the water is automatically diffused from the raw water side with low osmotic pressure to the draw solution side with high osmotic pressure through the selective permeable membrane.
  • the process does not require external pressure and energy.
  • forward osmosis can be operated at low pressure or even without pressure, so the energy consumption is low; under low pressure operation, the formation of filter cake layer caused by no pressure has the advantages of Low membrane fouling characteristics; in the case of sufficient osmotic pressure difference, there can be high water recovery rate that cannot be achieved by traditional separation membranes.
  • forward osmosis technology As a new type of membrane separation technology, has developed rapidly in recent years, and has also become a research hotspot for researchers at home and abroad, and has been applied in food, pharmacy, energy, etc. It shows good application prospects in many fields, especially in seawater desalination, drinking water treatment and wastewater treatment.
  • the purpose of the present invention is to provide a forward osmosis membrane with strong oxidation resistance that can be used safely and stably under strong oxidative conditions.
  • Another object of the present invention is to provide a method for preparing an oxidation-resistant forward osmosis membrane that can be used safely and stably under strong oxidizing conditions.
  • the invention relates to a forward osmosis membrane.
  • the provided forward osmosis membrane comprises a modified hydrophilic polymer film layer, which contains a hydrophilic polymer and an antioxidant; the hydrophilic polymer film layer passes through It is prepared by mixing hydrophilic polymer materials into a solvent system containing an antioxidant to obtain a casting solution, and performing film formation and solvent removal on the casting solution.
  • the hydrophilic polymer material constituting the hydrophilic polymer film layer includes at least one selected from the following: polyacrylonitrile, polyacrylate, polymethyl methacrylate, cellulose acetate, Cellulose triacetate, polyvinyl alcohol, polyethylene oxide and polyvinyl acetate; Described antioxidant is hindered phenolic antioxidant; Described antioxidant is preferably selected from following at least one: 2,6 -Di-tert-butyl-4-methylphenol, pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxy)phenylpropionate, 1,3,5-tris(3,5-di-tert-butyl- 4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1h,3h,5h)-trione).
  • Another preferred solution of the present invention is: in the casting solution, the mass ratio of the hydrophilic polymer to the antioxidant is: 8-15: 0.1-1; preferably 9-14: 0.2-0.9, more preferably 10-13:0.2-0.7, more preferably 8:0.2, or 13:0.5 or 13:0.2 or 11:0.3.
  • Another preferred solution of the present invention is: it also includes a supporting grid made of hydrophilic polyester screen or non-woven fabric, and the hydrophilic polymer film layer is laminated on the supporting grid, when the supporting grid
  • the lattice is a polyester mesh
  • it has a thickness of 30 ⁇ m-80 ⁇ m and an aperture of 100-200 mesh; preferably a thickness of 30 ⁇ m, 50 ⁇ m, 60 ⁇ m, 70 ⁇ m or 80 ⁇ m, and a diameter of 100 mesh, 120 mesh or 150 mesh
  • the forward osmosis membrane It has a thickness of 30 ⁇ m-150 ⁇ m, preferably 30 ⁇ m-100 ⁇ m, more preferably 30 ⁇ m-80 ⁇ m, more preferably 30 ⁇ m, 50 ⁇ m, 60 ⁇ m or 70 ⁇ m.
  • Another preferred solution of the present invention is: the proportion of each mass in the casting solution is: 8-15wt.% of the hydrophilic polymer, 0.1-1wt.% of the antioxidant; its solvent system includes 5-20wt. % acetone, 5-10wt.% methanol and 6-8wt.% lactic acid, the rest is 1,4-dioxane; preferably: hydrophilic polymer 9-14wt.%, antioxidant 0.2-0.9wt.
  • hydrophilic polymer is 10-13wt .%, the antioxidant is 0.3-0.7wt.%; its solvent system includes 10-20wt.% acetone, 6-8wt.% methanol and 6-8wt.% lactic acid, and the rest is 1,4-dioxane; more Preferably, the hydrophilic polymer is 13wt.% cellulose triacetate, the mass percent of 1,4-dioxane is 53.5wt.%, the mass percent of acetone is 19wt.%, and the mass percent of methanol is 8wt.%, 2, The mass percent of 6-di-tert-butyl-4-methylphenol is 0.5wt.%, and the mass percent of lactic acid is 6wt.%.
  • it is cellulose triacetate with a hydrophilic polymer of 13wt.%, 1,4 -Dioxane mass percent is 53.8wt.%, acetone mass percent is 19wt.%, methanol mass percent is 8wt.%, 2,6-di-tert-butyl-4-methylphenol mass percent is 0.2wt.% , the mass percent of lactic acid is 6wt.%; or another preferred cellulose triacetate is 11wt.% of the hydrophilic polymer, the mass percent of 1,4-dioxane is 55.7wt.%, and the mass percent of acetone is 19wt.%. %, the mass percent of methanol is 8wt.%, the mass percent of 2,6-di-tert-butyl-4-methylphenol is 0.3wt.%, and the mass percent of lactic acid is 6wt.%.
  • the present invention also relates to the preparation method that provides forward osmosis membrane, and described membrane comprises the hydrophilic polymer film layer of modification, and described method comprises:
  • the step (b) is further as follows: pour the casting solution after degassing in the step (a-1) on a glass plate or a light glass plate covered with a hydrophilic support grid, and use a scraping machine to make a film of a certain thickness. Nascent forward osmosis membrane;
  • the obtained nascent forward osmosis membrane is left standing in the air, so that the solvent is volatilized and a dense cortex is formed on the outer layer;
  • step (d) by immersing the second nascent forward osmosis membrane into deionized water, its gel phase separation is formed into a membrane;
  • step (e) soaking the obtained forward osmosis membrane in step (d) in deionized water to remove residual organic solvent;
  • the hydrophilic supporting mesh material is polyester mesh or non-woven fabric; when it is polyester mesh, its thickness is 30 ⁇ m-80 ⁇ m, and the aperture is 100 mesh-200 mesh; preferably 30 ⁇ m, 50 ⁇ m , thickness of 60 ⁇ m or 70 ⁇ m, aperture of 100 mesh, 120 mesh or 150 mesh;
  • the hydrophilic polymer material is selected from polyacrylonitrile, polyacrylate, polymethyl methacrylate, cellulose acetate, cellulose triacetate , at least one of polyvinyl alcohol, polyethylene oxide and polyvinyl acetate;
  • the antioxidant is a hindered phenolic antioxidant;
  • the solvent system is 1,4-dioxane, acetone, A mixture of methanol and lactic acid.
  • the hindered phenolic antioxidant is selected from 2,6-di-tert-butyl-4-methylphenol, tetrakis(3,5-di-tert-butyl-4-hydroxyl) pentaerythritol phenylpropionate, 1,3, At least one of 5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1h,3h,5h)-trione) .
  • the mass proportion of the hydrophilic polymer in the casting solution is 8-15wt.%; the mass proportion of the antioxidant is 0.1-1wt.%; preferably the hydrophilic polymer in the casting solution
  • the mass proportion of the antioxidant is 9-14wt.%; the mass proportion of the antioxidant is 0.2-0.9wt.%; it is further preferred that the mass proportion of the hydrophilic polymer in the casting solution is 10-13wt.%;
  • the mass proportion of the oxidizing agent is 0.2-0.7wt.%; more preferably the mass proportion of the hydrophilic polymer is 8wt.%; the mass proportion of the antioxidant is 0.2wt.%; or more preferably the mass proportion of the hydrophilic polymer
  • the mass proportion is 13wt.%; the mass proportion of antioxidant is 0.5wt.% or 0.2wt.%; or more preferably the mass proportion of hydrophilic polymer is 11wt.%; the mass proportion of antioxidant is 0.3wt.% .%.
  • the solvent system components and their mass proportions in the casting solution are: acetone mass percent 5-20wt.%, methanol mass percent 5-10wt.%, lactic acid mass percent 6-8wt.%, and the rest is 1 , 4-dioxane; preferably: acetone mass percent 7-20wt.%, methanol mass percent 5-8wt.%, lactic acid mass percent 6-8wt.%, the rest is 1,4-dioxane; more Preferably: acetone mass percent 10-20wt.%, methanol mass percent 6-8wt.%, lactic acid mass percent 6-8wt.%, the rest is 1,4-dioxane; more preferably acetone mass percent is 19wt. %, the mass percentage of methanol is 8wt.%, the mass percentage of lactic acid is 6%, and the rest is 1,4-dioxane.
  • the hydrophilic support grid is a polyester mesh with a thickness of 30 ⁇ m or 50 ⁇ m or 70 ⁇ m and a pore size of 100 mesh or 120 mesh or 150 mesh, which is used after pre-cleaning treatment; the pre-cleaning treatment steps are: The polyester screen is soaked with 10% sodium hydroxide and 2% hydrochloric acid for 1 hour to remove the impurities adsorbed on the surface, then rinsed with deionized water, and dried for later use; The thickness is 30 ⁇ m-150 ⁇ m, preferably 30 ⁇ m-100 ⁇ m, more preferably 30 ⁇ m-80 ⁇ m, more preferably 30 ⁇ m, 50 ⁇ m, 60 ⁇ m, or 70 ⁇ m.
  • the mixing condition is stirring at a temperature of 30-50°C for 12-48h to make it evenly mixed; preferably stirring at a temperature of 40-50°C for 12-32h; more preferably Stirring at 40°C for 24 hours;
  • the defoaming method is to stand still for 12-36h to fully defoam or assist ultrasonic defoaming; preferably stand for 24h;
  • the condition for standing in the air is not higher than the temperature of 25°C
  • the standing time is 30-90 seconds to make it form a compact dense cortex, preferably the environment of temperature 25 °C and humidity 90%, the standing time is 30-60 seconds.
  • the membrane in the step (e) of the preparation method, before the membrane is soaked in deionized water, the membrane is first placed in a water bath at 40-50°C for heat treatment for 5-20 minutes, and then placed in deionized water to remove residual organic solvents.
  • the soaking time is 12-36 hours; preferably heat-treated in a water bath at 50°C for 15 minutes and then soaked in ionized water for 24 hours; the concentration of sodium metabisulfite in step (f) of the preparation method is between 0.5-2%.
  • the forward osmosis membrane provided by the invention can be used for strong oxidative waste water treatment, water purification, filtration and purification of food and medicine.
  • the invented forward osmosis membrane is a modified membrane obtained by mixing antioxidants in the hydrophilic polymer layer, especially adding hindered phenolic antioxidants. Strong oxidation resistance effect, so as to produce an oxidation-resistant forward osmosis membrane that can still be used safely and stably under strong oxidative conditions.
  • forming a highly hydrophilic hydrophilic polymer layer on the non-woven fabric or polyester screen can improve water permeability and water flux and salt retention rate, while the hydrophilic polymer film
  • the antioxidants in the layer especially hindered phenolic antioxidants such as selected from 2,6-di-tert-butyl-4-methylphenol, ensure the oxidation resistance and chemical resistance of the forward osmosis membrane, and can effectively reduce the raw water Oxidation limit, reducing the input of pre-treatment reducing agent, thereby reducing operating costs, while improving the operational stability of the forward osmosis membrane, improving the efficiency of purifying and separating water, and prolonging the service life of the forward osmosis membrane.
  • the use of membrane systems reduces costs.
  • the preparation method of the forward osmosis membrane of the present invention includes forming a hydrophilic polymer membrane layer with oxidation resistance under optimized conditions, which not only has high membrane flux, high salt rejection rate, but also has high resistance to oxidation. Oxidation, reduce the oxidative limit of raw water entering the membrane, improve the operation stability of the forward osmosis membrane, thereby improving the efficiency of purifying and separating water, prolonging the service life of the forward osmosis membrane, and reducing the cost for the use of the entire osmosis membrane system.
  • Fig. 1 is a flow chart of the preparation process of the forward osmosis membrane of the present invention.
  • Pre-preparation of the support grid remove impurities from the polyester screen, wash it and dry it for later use; whether to perform pre-preparation of the polyester screen according to needs;
  • nascent forward osmosis membrane pours the completely defoamed casting solution on a glass plate covered with a pre-treated clean polyester screen or directly on a light glass plate, and use a scraping machine to make a film of a certain thickness. Nascent forward osmosis membrane;
  • the film obtained in step 4 is placed in the air for a few seconds at a certain temperature and humidity to form a dense skin layer, and then immersed in deionized water to separate the gel into a film;
  • the temperature is preferably not higher than 25°C, and the humidity is not lower than 90% in the air for 30-90 seconds;
  • Preserve for future use take out the forward osmosis membrane and rinse it with deionized water, and then store it in a solution of 0.5-2% sodium metabisulfite for future use. Whether to save it for future use as needed.
  • step 2 The casting solution obtained in step 2 is allowed to stand for 24 hours for sufficient degassing or assisted ultrasonic degassing;
  • step 4 Put the film obtained in step 4 in an environment with a temperature of 25° C. and a humidity of 90%, and let it stand in the air for 60 seconds to form a dense skin layer, and then immerse it in deionized water to make the gel phase-separate into a film;
  • step 5 Put the membrane obtained in step 5 into a water bath at 40-50° C. for heat treatment for 5-15 minutes, and then soak in deionized water for 24 hours to remove residual organic solvents.
  • the thickness of the forward osmosis membrane prepared by the above steps is 50 ⁇ m.
  • the membrane flux can reach 11.5 L/(m 2 *h)
  • the rejection rate of magnesium sulfate is greater than 98%
  • the membrane performance does not decrease after soaking for 30 days under the condition that the ORP value simulated by hydrogen peroxide is +800mv. See Table 1 for specific performance tests.
  • step 2 The casting solution obtained in step 1 is left to stand for 24 hours for sufficient degassing or assisted ultrasonic degassing;
  • step 3 Put the film obtained in step 3 in an environment with a temperature of 25° C. and a humidity of 90%, and let it stand in the air for 60 seconds to form a dense skin layer, and then immerse it in deionized water to make the gel phase-separate into a film;
  • step 4 Put the membrane obtained in step 4 into a water bath at 40-50° C. for heat treatment for 5-15 minutes, and then soak in deionized water for 24 hours to remove residual organic solvents.
  • the thickness of the forward osmosis membrane prepared by the above steps is 50 ⁇ m, with 0.5mol/L sodium chloride and 0.01mol/L magnesium sulfate with an ORP value of +800mv as the draw liquid and feed liquid respectively, the membrane flux can reach 11.2 L/(m 2 *h), the rejection rate of magnesium sulfate is greater than 98%, and the membrane performance does not decrease after soaking for 30 days under the condition that the ORP value simulated by hydrogen peroxide is +800mv. See Table 1 for specific performance tests.
  • step 2 The casting solution obtained in step 1 is left to stand for 24 hours for sufficient degassing or assisted ultrasonic degassing;
  • step 3 Put the film obtained in step 3 in an environment with a temperature of 25° C. and a humidity of 90%, and let it stand in the air for 60 seconds to form a dense skin layer, and then immerse it in deionized water to make the gel phase-separate into a film;
  • step 4 Put the membrane obtained in step 4 into a water bath at 40-50° C. for heat treatment for 5-15 minutes, and then soak in deionized water for 24 hours to remove residual organic solvents.
  • the thickness of the forward osmosis membrane prepared by the above steps is 50 ⁇ m, and 0.5mol/L sodium chloride and 0.01mol/L magnesium sulfate with an ORP value of +800mv are used as the draw liquid and feed liquid respectively, and the membrane flux can reach 11.3 L/(m 2 *h), the rejection rate of magnesium sulfate is greater than 98%, and the membrane performance does not decrease after soaking for 30 days under the condition that the ORP value simulated by hydrogen peroxide is +800mv. See Table 1 for specific performance tests.
  • step 2 The casting solution obtained in step 1 is left to stand for 24 hours for sufficient degassing or assisted ultrasonic degassing;
  • step 3 Put the film obtained in step 3 in an environment with a temperature of 25° C. and a humidity of 90%, and let it stand in the air for 60 seconds to form a dense skin layer, and then immerse it in deionized water to make the gel phase-separate into a film;
  • step 4 Put the membrane obtained in step 4 into a water bath at 50° C. for heat treatment for 15 minutes, and then soak in deionized water for 24 hours to remove residual organic solvents.
  • the thickness of the forward osmosis membrane prepared by the above steps is 70 ⁇ m.
  • the membrane flux can reach 12.5 L/(m 2 *h)
  • the rejection rate of magnesium sulfate is greater than 98%
  • the membrane performance does not decrease after soaking for 30 days under the condition that the ORP value simulated by hydrogen peroxide is +800mv. See Table 1 for specific performance tests.
  • Table 1 uses 0.5mol/L sodium chloride extraction solution and 0.01mol/L magnesium sulfate with an ORP value of +800mv as feed solution to evaluate membrane performance.
  • the forward osmosis membrane of the present invention added with antioxidants has strong oxidation resistance, even after 30 days of immersion in water with a strong oxygen potential, the performance of the membrane is not affected.
  • the forward osmosis membrane formed by the existing cellulose triacetate and the forward osmosis membrane of the existing product its oxidation resistance is not strong, and the longer the soaking time, the worse the membrane performance declines.
  • concentrations of sodium hydroxide, hydrochloric acid and sodium metabisulfite in the examples of the present invention are calculated by mass ratio.
  • the invented forward osmosis membrane is a modified membrane obtained by mixing antioxidants in the hydrophilic polymer layer, especially adding hindered phenolic antioxidants. Strong oxidation resistance effect, so as to produce an oxidation-resistant forward osmosis membrane that can still be used safely and stably under strong oxidative conditions.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
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Abstract

一种正渗透膜及其制备方法。该正渗透膜具有包括亲水性支撑网格、混合有抗氧化剂的亲水性聚合物膜层的改性膜结构。该支撑网格为无纺布或聚酯筛网。

Description

正渗透膜及其制备方法
相关申请的交叉引用
本申请主张在2021年9月9日在中国提交的中国专利申请号No.202111056457.0的优先权，其全部内容通过引用包含于此。
技术领域
本发明涉及高分子分离膜及其制备技术领域，具体涉及一种耐氧化性正渗透膜及其制备方法。
背景技术
正渗透(FO)过程是以汲取液和原料液间的渗透压差为驱动力，使水由低渗透压的原水侧通过选择性透过膜自动扩散至高渗透压的汲取液侧的过程，此过程不需要外加压力和能量。
区别于以压力驱动的膜分离过程如超滤、纳滤和反渗透技术，正渗透可以低压甚至无压操作，因而运行能耗低；低压运行下，无压力导致的滤饼层的形成，具有低的膜污染特征；在足够的渗透压差的情况下，可以有传统分离膜无法达到的高水回收率。
基于上述正渗透的特点，正渗透技术作为一种新型的膜分离技术近几年得到了迅速的发展，同时也成为了国内外研究者研究的热点，并已经应用于在食品、药学、能源等领域，在许多领域，特别是在海水淡化、饮用水处理和废水处理中展现出很好的应用前景。
理想的正渗透膜应同时具有良好的亲水性、通量高、高截盐率、抗污染性好等性能，这些是近年来本领域研究的热点方向。目前业界通用的认为醋酸纤维素正渗透膜相比芳香族聚酰胺复合膜耐氧化性更强，用醋酸纤维素作为正渗透膜的膜材料成为本领域研究及产品化的主流，如现有中国专利201410050442.7，其揭示了一种非对称的醋酸纤维素正渗透膜，旨在降低内浓差极化，提高正渗透通量和耐氯性。这些技术研究都旨在提高通量、截盐率、减少内浓差等，对于膜的耐氧化性方面没有提及及改进。
但在实际应用时，特别是在催化氧化工艺段后的废水的氧化性较强的情况下运行使用时仍会对膜造成损伤，而传统的前端添加还原剂的方法受水质、水量的波动无法保证后端的膜系统能绝对的安全，目前缺乏制备具有较强耐氧化性的正渗透膜应对这一困境。如上述现有中国专利201410050442.7，其制造的膜无法直接在氧化性强的废水处理或其他原水中进行有效使用，其膜因受原水环境氧化性的损害而使得膜的使用寿命短，增加了整体膜系统的使用成本。
发明内容
本发明的目的是提供一种对较强氧化性条件下可以安全稳定使用的强耐氧化性正渗透膜。
本发明的另一目的是提供一种制备对较强氧化性条件下可以安全稳定使用的耐氧化性正渗透膜的方法。
为了实现上述目的，本发明采用的技术方案为：
本发明涉及一种正渗透膜。所提供的正渗透膜包括改性的亲水性聚合物膜层，所述的亲水性聚合物膜层中含有亲水性聚合物和抗氧化剂；所述的亲水性聚合物膜层通过混合亲水性聚合物材料到含有抗氧化剂的溶剂系统中混合获得铸膜液、并对铸膜液进行成膜、去除溶剂工艺制备而成。
本发明的优选方案为：构成亲水性聚合物膜层的亲水性聚合物材料包括选自以下的至少一种：聚丙烯腈、聚丙烯酸酯、聚甲基丙烯酸甲酯、醋酸纤维素、三醋酸纤维素、聚乙烯醇、聚环氧乙烷和聚醋酸乙烯酯；所述的抗氧化剂为位阻酚类抗氧化剂；所述的抗氧化剂优选自下述的至少一种：2,6-二叔丁基-4-甲基苯酚、四(3,5-二叔丁基-4-羟基)苯丙酸季戊四醇酯、1,3,5-三(3,5-二叔丁基-4-羟基苄基)-1,3,5-三嗪-2,4,6(1h,3h,5h)-三酮)。
本发明的另一优选方案为：所述铸膜液中，亲水性聚合物与抗氧化剂的质量占比为：8-15：0.1-1；优选为9-14：0.2-0.9，进一步优选为10-13：0.2-0.7，更优选为8：0.2，或为13：0.5或13：0.2或11：0.3。
本发明的再一优选方案为：还包括亲水性聚酯筛网或无纺布构成的支撑网格，所述的亲水性聚合物膜层叠层于支撑网格上，当所述支撑网格为聚酯筛网时其具有30μm-80μm的厚度，100-200目的孔径；优选为30μm、50μm、60μm、70μm或80μm的厚度，100目、120目或150目的孔径；所述正渗透膜具有30μm-150μm厚度,优选为30μm-100μm，进一步优选为30μm-80μm,更优选为30μm、50μm、60μm或70μm。
本发明的再一优选方案为：所述的铸膜液中各质量占比为：亲水聚合物为8-15wt.％，抗氧化剂为0.1-1wt.％；其溶剂系统包括5-20wt.％丙酮、5-10wt.％甲醇及6-8wt.％乳酸、其余为1,4-二氧六环；优选为：亲水聚合物为9-14wt.％，抗氧化剂为0.2-0.9wt.％；其溶剂系统包括7-20wt.％丙酮、5-8wt.％甲醇及6-8wt.％乳酸、其余为1,4-二氧六环；更优 选为：亲水聚合物为10-13wt.％，抗氧化剂为0.3-0.7wt.％；其溶剂系统包括10-20wt.％丙酮、6-8wt.％甲醇及6-8wt.％乳酸、其余为1,4-二氧六环；更优选为亲水聚合物为13wt.％的三醋酸纤维素，1，4-二氧六环质量百分比为53.5wt.％，丙酮质量百分比为19wt.％，甲醇质量百分比为8wt.％，2,6-二叔丁基-4-甲基苯酚质量百分比为0.5wt.％，乳酸质量百分比为6wt.％；或进一步更优选为亲水聚合物为13wt.％的三醋酸纤维素，1，4-二氧六环质量百分比为53.8wt.％，丙酮质量百分比为19wt.％，甲醇质量百分比为8wt.％，2,6-二叔丁基-4-甲基苯酚质量百分比为0.2wt.％，乳酸质量百分比为6wt.％；或另一优选为亲水聚合物为11wt.％的三醋酸纤维素，1，4-二氧六环质量百分比为55.7wt.％，丙酮质量百分比为19wt.％，甲醇质量百分比为8wt.％，2,6-二叔丁基-4-甲基苯酚质量百分比为0.3wt.％，乳酸质量百分比为6wt.％。
根据本发明的另一目的，本发明还涉及提供正渗透膜的制备方法，所述膜包括改性的亲水性聚合物膜层，所述方法包括：
(a)制备铸膜液：将亲水性聚合物材料、抗氧剂、水溶性有机溶剂系统进行混合，获得铸膜液；
(b)将所述的铸膜液涂布到铺有亲水性支撑网格的玻璃板或光玻璃板上，获得初生态正渗透膜；
(c)对初生态正渗透膜进行外层处理，去除溶剂，在初生态正渗透膜的外层上形成致密皮层，获得第二初生态正渗透膜；
(d)对第二初生态正渗透膜进行分相成膜或界面成膜，获得所述的正渗透膜。
其中，还包括如下步骤:
(a-1)将步骤(a)所得到的铸膜液进行脱泡；
所述步骤(b)进一步为：将步骤(a-1)脱泡后的铸膜液倒在铺有亲水性支撑网格的玻璃板或光玻璃板上，用刮膜机制得一定厚度的初生态正渗透膜；
所述步骤(c)的外层处理及去除溶剂通过将所得到的初生态正渗透膜在空气中静置,使溶剂挥发并在外层形成致密皮层；
所述步骤(d)中通过将第二初生态正渗透膜浸入到去离子水中使其凝胶分相成膜；
(e)将步骤(d)所得到的正渗透膜浸泡在去离子水中去除残留的有机溶剂；
(f)取出正渗透膜用去离子水冲洗后，放于偏重亚硫酸钠的溶液中保存备用。
其中，所述的亲水性支撑网格材料为聚酯筛网或无纺布；当为聚酯筛网时，其厚度为30μm-80μm、孔径为100目-200目；优选为30μm、50μm、60μm或70μm的厚度，100目、120目或150目的孔径；所述的亲水聚合物材料选自聚丙烯腈、聚丙烯酸酯、聚甲基丙烯酸甲酯、醋酸纤维素、三醋酸纤维素、聚乙烯醇、聚环氧乙烷和聚醋酸乙烯酯中的至少一种；所述的抗氧化剂为位阻酚类抗氧化剂；所述溶剂系统为1，4-二氧六环、丙酮、甲醇、乳酸的混合液。所述位阻酚类抗氧化剂选自2,6-二叔丁基-4-甲基苯酚、四(3,5-二叔丁基-4-羟基)苯丙酸季戊四醇酯、1,3,5-三(3,5-二叔丁基-4-羟基苄基)-1,3,5-三嗪-2,4,6(1h,3h,5h)-三酮)中的至少一种。
其中，所述铸膜液中亲水性聚合物的质量占比为8-15wt.％；抗氧化剂的质量占比为0.1-1wt.％；优选为所述铸膜液中亲水性聚合物的质量占比为9-14wt.％；抗氧化剂质量占比为0.2-0.9wt.％；进一步优选为所述铸膜液中亲水性聚合物的质量占比为10-13wt.％；抗氧化剂质量占比为0.2-0.7wt.％；更优选为亲水性聚合物的质量占比为8wt.％；抗氧化剂质量占比为0.2wt.％；或更优选为亲水性聚合物的质量占比为13wt.％；抗氧化剂质量占比为0.5wt.％或0.2wt.％；或更优选为亲水性聚合物的质量占比为11wt.％；抗氧化剂质量占比为0.3wt.％。
其中，所述溶剂系统组分及在铸膜液中的质量占比为：丙酮质量百分比5-20wt.％，甲醇质量百分比5-10wt.％，乳酸质量百分比6-8wt.％，其余为1,4-二氧六环；优选为：丙酮质量百分比7-20wt.％，甲醇质量百分比5-8wt.％，乳酸质量百分比6-8wt.％，其余为1,4-二氧六环；更优选为：丙酮质量百分比10-20wt.％，甲醇质量百分比6-8wt.％，乳酸质量百分比6-8wt.％，其余为1,4-二氧六环；进一步优选为丙酮质量百分比为19wt.％、甲醇质量百分比为8wt.％、乳酸质量百分比为6％、其余为1，4-二氧六环。
其中，所述的亲水性支撑网格为聚酯筛网，其厚度为30μm或50μm、70μm、孔径为100目或120目或150目，经过预清洁处理后使用；预清洁处理步骤为：聚酯筛网分别用10％的氢氧化钠、2％的盐酸浸泡处理1小时去除表面吸附的杂质，然后用去离子水冲洗，烘干备用；所述用刮膜机制得初生态正渗透膜厚度为30μm-150μm，优选为30μm-100μm，进一步优选为30μm-80μm,更优选为30μm、50μm、60unm、或70μm。
其中，所述制备方法的步骤(a)中，混合条件为在30-50℃的温度下搅拌12-48h，使其混合均匀；优选为40-50℃的温度下搅拌12-32h；更优选为40℃温度下搅拌24小时；所述 脱泡方式为静置12-36h充分脱泡或辅助超声脱泡；优选静置24h；所述在空气中静置的条件是不高于温度25℃和不低于湿度90％的环境，静置时间为30-90秒使其形成致密的致密皮层，优选为温度25℃和湿度90％的环境，静置时间为30-60秒。
其中，所述制备方法的步骤(e)中，膜在去离子水中浸泡前，先将膜放入40-50℃的水浴中热处理5-20分钟，放入去离子水中去除残留的有机溶剂的浸泡时间为12-36小时；优选50℃水浴中热处理15分钟后放入离子水中浸泡24小时；所述制备方法的步骤(f)中的偏重亚硫酸钠的浓度为0.5-2％之间。
本发明的提供的正渗透膜可用于强氧化性的废水处理、水净化、食品、药品的过滤、净化。
本发明提供的正渗透膜及其制备方法中，所发明的正渗透膜是一种改性膜，通过在亲水聚合物层中混合抗氧化剂特别是加入位阻酚类抗氧化剂共混，获得强耐氧化性效果，从而制得可以在较强氧化性条件下，仍然可以安全稳定使用的耐氧化性正渗透膜。
同时，本发明的另一方案中在无纺布或聚酯筛网上形成高亲水性的亲水性聚合物层能够提高渗水性和水通量及盐截留率，而亲水性聚合物膜层中的抗氧化剂特别是位阻酚类抗氧化剂如选自2,6-二叔丁基-4-甲基苯酚保证了正渗透膜的耐氧化性和化学品耐受性，可以有效降低原水的氧化性限制，减少前处理的还原剂的投入，从而降低运行成本，同时提高了正渗透膜的运行稳定性，提高了净化分离水的效率，延长了正渗透膜的使用寿命，为整个渗透膜系统的使用降低成本。
同时，本发明的正渗透膜的制备方法包括在优化条件下形成具有耐氧化性的亲水性聚合物膜层，不仅具有高的膜通量，高的盐截留率，同时还具有高的耐氧化性，降低进膜原水的氧化性限制，提高了正渗透膜的运行稳定性，从而提高了净化分离水的效率，延长了正渗透膜的使用寿命，为整个渗透膜系统的使用降低成本。
附图的简要说明
图1为本发明正渗透膜制备工艺流程图。
本发明的实施方式
为更进一步阐述本发明为达成预定目的所采取的技术手段及功效,以下结合附图及较佳实施例，对依据本发明提出的正渗透膜及其制备方法，其具体实施方式、结构、制备方法、 特征及其功效，说明如后。本发明提供以下的实施例为进一步描述本发明，但所描述的实施例仅用于说明本发明不是限制本发明。
如图1所示，为本发明正渗透膜制备工艺流程图，具体工艺流程说明如下：
(1)支撑网格预准备：将聚酯筛网除杂质、冲洗干净处理后烘干备用；根据需要是否进行聚酯筛网的预准备；
(2)制备铸膜液：将亲水性聚合物材料、抗氧化剂和有机溶剂系统进行均匀混合。本发明进一步为亲水性聚合物材料、位阻酚类抗氧化剂加入到水溶性有机溶剂系统混合液中，在30℃-50℃的温度下搅拌12-48h之后得到均匀的铸膜液；
(3)脱泡：将步骤2所得到的铸膜液静置12-36h充分脱泡或辅助超声脱泡；
(4)初生态正渗透膜制备：将完全脱泡的铸膜液倒在铺有预处理干净的聚酯筛网的玻璃板或直接倒在光玻璃板上，用刮膜机制得一定厚度的初生态正渗透膜；
(5)成膜：将步骤4所得到的膜在一定温度和湿度环境下，静置在空气中数秒使其形成致密的皮层，之后浸入到去离子水中使其凝胶分相成膜；本发明中优选为温度不高于25℃，湿度不低于90％的空气中静置30-90秒；
(6)优化处理：将步骤5所得到的膜放入40-50℃的水浴中热处理5-20分钟，随后浸泡在去离子水中24h去除残留的有机溶剂，得到进一步优化的正渗透膜；
(7)保存备用：取出正渗透膜用去离子水冲洗后，放在0.5-2％偏重亚硫酸钠的溶液中保存备用。根据需要是否进行保存备用。
实施例1
(1)将厚度为30μm，200目的聚酯筛网分别用2％的盐酸、10％的氢氧化钠浸泡处理1小时去除表面吸附的杂质，然后用去离子水冲洗，烘干备用；
(2)将三醋酸纤维素质量百分比13wt.％加入到1，4-二氧六环质量百分比53.5wt.％、丙酮质量百分比19wt.％、甲醇质量百分比8wt.％、2,6-二叔丁基-4-甲基苯酚质量百分比0.5wt.％及乳酸质量百分比6％的混合液中，在40℃的温度下搅拌24h之后得到均匀的铸膜液；
(3)将步骤2所得到的铸膜液静置24h充分脱泡或辅助超声脱泡；
(4)将完全脱泡的铸膜液倒在铺有聚酯筛网(厚度30μm)的玻璃板上，用刮膜机制得厚度50μm初生态正渗透膜；
(5)将步骤4所得到的膜在温度25℃和湿度90％环境中，静置在空气中60秒使其形成致密的皮层，之后浸入到去离子水中使其凝胶分相成膜；
(6)将步骤5所得到的膜放入40-50℃的水浴中热处理5-15分钟，随后浸泡在去离子水中24h去除残留的有机溶剂。
膜性能：
上述步骤制备的正渗透膜厚度为50μm，以0.5mol/L氯化钠、添加双氧水的ORP值为+800mv的0.01mol/L硫酸镁分别作为汲取液和料液，其膜通量可以达到11.5L/(m 2*h),硫酸镁的截留率大于98％，在以双氧水模拟的ORP值为+800mv的条件下浸泡30天膜性能未下降。具体性能测试参见表1。
实施例2
(1)将三醋酸纤维质量百分比13wt.％加入到1，4-二氧六环质量百分比53.8wt.％、丙酮质量百分比19wt.％、甲醇质量百分比8wt.％、2,6-二叔丁基-4-甲基苯酚质量百分比0.2wt.％及乳酸质量百分比6％的混合液中，在40℃的温度下搅拌24h之后得到均匀的铸膜液；
(2)将步骤1所得到的铸膜液静置24h充分脱泡或辅助超声脱泡；
(3)将完全脱泡的铸膜液倒在玻璃板上，用刮膜机制得厚度50μm初生态正渗透膜；
(4)将步骤3所得到的膜在温度25℃和湿度90％环境中，静置在空气中60秒使其形成致密的皮层，之后浸入到去离子水中使其凝胶分相成膜；
(5)将步骤4所得到的膜放入40-50℃的水浴中热处理5-15分钟，随后浸泡在去离子水中24h去除残留的有机溶剂。
膜性能：
上述步骤制备的正渗透膜厚度为50μm，以0.5mol/L氯化钠、添加双氧水的ORP值为+800mv的0.01mol/L硫酸镁分别作为汲取液和料液，其膜通量可以达到11.2L/(m 2*h),硫酸镁的截留率大于98％，在以双氧水模拟的ORP值为+800mv的条件下浸泡30天膜性能未下降。具体性能测试参见表1。
实施例3
(1)将三醋酸纤维质量百分比13wt.％加入到1，4-二氧六环质量百分比53.8wt.％、丙酮质量百分比19wt.％、甲醇质量百分比8wt.％、四(3,5-二叔丁基-4-羟基)苯丙酸季戊四醇酯质量百分比0.2wt.％及乳酸质量百分比6％的混合液中，在40℃的温度下搅拌24h之后得到均匀的铸膜液；
(2)将步骤1所得到的铸膜液静置24h充分脱泡或辅助超声脱泡；
(3)将完全脱泡的铸膜液倒在玻璃板上，用刮膜机制得厚度50μm初生态正渗透膜；
(4)将步骤3所得到的膜在温度25℃和湿度90％环境中，静置在空气中60秒使其形成致密的皮层，之后浸入到去离子水中使其凝胶分相成膜；
(5)将步骤4所得到的膜放入40-50℃的水浴中热处理5-15分钟，随后浸泡在去离子水中24h去除残留的有机溶剂。
膜性能：
上述步骤制备的正渗透膜厚度为50μm，以0.5mol/L氯化钠、添加双氧水的ORP值为+800mv的0.01mol/L硫酸镁分别作为汲取液和料液，其膜通量可以达到11.3L/(m 2*h),硫酸镁的截留率大于98％，在以双氧水模拟的ORP值为+800mv的条件下浸泡30天膜性能未下降。具体性能测试参见表1。
实施例4
(1)将三醋酸纤维质量百分比11wt.％加入到1，4-二氧六环质量百分比55.7wt.％、丙酮质量百分比19wt.％、甲醇质量百分比8wt.％、2,6-二叔丁基-4-甲基苯酚质量百分比0.3wt.％及乳酸质量百分比6％的混合液中，在40℃的温度下搅拌24h之后得到均匀的铸膜液；
(2)将步骤1所得到的铸膜液静置24h充分脱泡或辅助超声脱泡；
(3)将完全脱泡的铸膜液倒在玻璃板上，用刮膜机制得厚度70μm初生态正渗透膜；
(4)将步骤3所得到的膜在温度25℃和湿度90％环境中，静置在空气中60秒使其形成致密的皮层，之后浸入到去离子水中使其凝胶分相成膜；
(5)将步骤4所得到的膜放入50℃的水浴中热处理15分钟，随后浸泡在去离子水中24h去除残留的有机溶剂。
膜性能：
上述步骤制备的正渗透膜厚度为70μm，以0.5mol/L氯化钠、添加双氧水的ORP值为+800mv的0.01mol/L硫酸镁分别作为汲取液和料液，其膜通量可以达到12.5L/(m 2*h),硫酸镁的截留率大于98％，在以双氧水模拟的ORP值为+800mv的条件下浸泡30天膜性能未下降。具体性能测试参见表1。
表1使用0.5mol/L氯化钠抽取液、添加双氧水的ORP值为+800mv的0.01mol/L硫酸镁作为料液的膜性能评估。
Figure PCTCN2022078220-appb-000001
通过表1可以看出，添加了抗氧化剂的本发明正渗透膜具有强的耐氧化性，即使在经过30天的较强氧电位水中浸泡，其膜的性能也没有受到影响。而对于现有的三醋酸纤维素构成的正渗透膜及现有产品的正渗透膜，其耐氧化性不强，随着浸泡时间越长，膜性能下降越厉害。
本发明实施例中氢氧化钠、盐酸及偏重亚硫酸钠的浓度按质量比算。
本发明提供的正渗透膜及其制备方法中，所发明的正渗透膜是一种改性膜，通过在亲水聚合物层中混合抗氧化剂特别是加入位阻酚类抗氧化剂共混，获得强耐氧化性效果，从而制得可以在较强氧化性条件下，仍然可以安全稳定使用的耐氧化性正渗透膜。
在此说明书中，本发明已参照其特定的实施例作了描述，但是，很显然仍可以做出各种修改和变换而不背离本发明的精神和范围。因此，本发明的说明书和附图被认为是说明性的而非限制性的。

Claims (12)

  1. 一种正渗透膜，其特征在于：包括改性的亲水性聚合物膜层，所述的亲水性聚合物膜层中含有亲水性聚合物和抗氧化剂；所述的亲水性聚合物膜层通过混合亲水性聚合物材料到含有抗氧化剂的溶剂系统中混合获得铸膜液、并对铸膜液进行成膜、去除溶剂工艺制备而成；所述铸膜液中亲水性聚合物为三醋酸纤维素，其质量占比为11-13wt.％；抗氧化剂为位阻酚类抗氧化剂2,6-二叔丁基-4-甲基苯酚，其质量占比为0.2-0.7wt.％；所述正渗透膜以0.5mol/L氯化钠、添加双氧水的ORP值为+800mv的0.01mol/L硫酸镁分别作为汲取液和料液，在经过以双氧水模拟的ORP值为+800mv的强氧电位水中浸泡30天后测试，膜性能未下降。
  2. 如权利要求1所述的正渗透膜，其特征在于：所述抗氧化剂在铸膜液中的质量占比为：0.3-0.5wt.％。
  3. 如权利要求1所述的正渗透膜，其特征在于：还包括亲水性聚酯筛网或无纺布构成的支撑网格，所述的亲水性聚合物膜层叠层于支撑网格上，当所述支撑网格为聚酯筛网时其具有30μm-80μm的厚度，100-200目的孔径；所述正渗透膜具有30μm-150μm厚度。
  4. 如权利要求1所述的正渗透膜，其特征在于：所述的铸膜液中，其溶剂系统包括5-20wt.％丙酮、5-10wt.％甲醇及6-8wt.％乳酸、其余为1,4-二氧六环。
  5. 一种正渗透膜的制备方法，其特征在于：所述膜包括改性的亲水性聚合物膜层，所述方法包括：(a)制备铸膜液：将亲水性聚合物材料、抗氧剂、水溶性有机溶剂系统进行混合，获得铸膜液；(b)将所述的铸膜液涂布到铺有亲水性支撑网格的玻璃板或光玻璃板上，获得初生态正渗透膜；(c)对初生态正渗透膜进行外层处理，去除溶剂，在初生态正渗透膜的外层上形成致密皮层，获得第二初生态正渗透膜；(d)对第二初生态正渗透膜进行分相成膜或界面成膜，获得所述的正渗透膜；所述铸膜液中亲水性聚合物为三醋酸纤维素，其质量占比为11-13wt.％；抗氧化剂为位阻酚类抗氧化剂2,6-二叔丁基-4-甲基苯酚，其质量占比为0.2-0.7wt.％；所述正渗透膜以0.5mol/L氯化钠、添加双氧水的ORP值为+800mv的0.01mol/L硫酸镁分别作为汲取液和料液，在经过以双氧水模拟的ORP值为+800mv的强氧电位水中浸泡30天后测试，膜性能未下降。
  6. 如权利要求5所述的正渗透膜的制备方法，其特征在于，还包括如下步骤:(a-1)将步骤(a)所得到的铸膜液进行脱泡；所述步骤(b)进一步为：将步骤(a-1)脱泡后的铸膜 液倒在铺有亲水性支撑网格的玻璃板或光玻璃板上，用刮膜机制得一定厚度的初生态正渗透膜；所述步骤(c)的外层处理及去除溶剂通过将所得到的初生态正渗透膜在空气中静置,使溶剂挥发并在外层形成致密皮层；所述步骤(d)中通过将第二初生态正渗透膜浸入到去离子水中使其凝胶分相成膜；(e)将步骤(d)所得到的正渗透膜浸泡在去离子水中去除残留的有机溶剂；(f)取出正渗透膜用去离子水冲洗后，放于偏重亚硫酸钠的溶液中保存备用。
  7. 如权利要求6所述的正渗透膜的制备方法，其特征在于：所述的亲水性支撑网格材料为聚酯筛网或无纺布；当为聚酯筛网时，其厚度为30μm-80μm、孔径为100目-200目；所述水溶性有机溶剂系统为1，4-二氧六环、丙酮、甲醇、乳酸的混合液。
  8. 如权利要求5所述的正渗透膜的制备方法，其特征在于：抗氧化剂的质量占比为0.3-0.5wt.％。
  9. 如权利要求5所述的正渗透膜的制备方法，其特征在于：所述铸膜液中溶剂系统组分及质量占比为：丙酮质量百分比5-20wt.％，甲醇质量百分比5-10wt.％，乳酸质量百分比6-8wt.％，其余为1,4-二氧六环。
  10. 如权利要求7所述的正渗透膜的制备方法，其特征在于：所述的亲水性支撑网格为聚酯筛网，其厚度为30μm或50μm或60μm或70μm、孔径为100目或150目，经过预清洁处理后使用；预清洁处理步骤为：聚酯筛网分别用10％的氢氧化钠、2％的盐酸浸泡处理1小时去除表面吸附的杂质，然后用去离子水冲洗，烘干备用；所述用刮膜机制得初生态正渗透膜厚度为30μm-150μm。
  11. 如权利要求6中所述的正渗透膜的制备方法，其特征在于：所述制备方法的步骤(a)中，混合条件为在30-50℃的温度下搅拌12-48h，使其混合均匀；所述脱泡方式为静置12-36h充分脱泡或辅助超声脱泡；所述在空气中静置的条件是温度不高于25℃和湿度不低于90％的环境，静置时间为30-90秒使其形成致密的致密皮层。
  12. 如权利要求6所述的正渗透膜的制备方法，其特征在于：所述制备方法的步骤(e)中，膜在去离子水中浸泡前，先将膜放入50℃的水浴中热处理15分钟，放入去离子水中去除残留的有机溶剂的浸泡时间为12-36小时；所述制备方法的步骤(f)中的偏重亚硫酸钠的浓度为0.5-2％之间。
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