Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D65/00—Accessories or auxiliary operations, in general, for separation processes or apparatus using semi-permeable membranes
  • B01D65/02—Membrane cleaning or sterilisation ; Membrane regeneration
• • 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
  • B01D71/56—Polyamides, e.g. polyester-amides
• • 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 present invention relates to a method for regenerating a semipermeable membrane.
• Membrane separation is widely used in many technical fields. For example, forward osmosis membranes, reverse osmosis membranes, nanofiltration membranes, ultrafiltration membranes, microfiltration membranes, and the like are used for the purposes of wastewater treatment, desalinization of seawater, concentration of intermediate compounds, purification of target substances, and the like.
• Patent Documents 1 to 3 disclose a technique in which, while a stock solution is flowing through the stock solution side of a forward osmosis membrane module, the flowing liquid on the draw solution side is switched from the draw solution to a cleaning liquid having a lower osmotic pressure than the stock solution, and the forward osmosis membrane is backwashed by utilizing the osmotic pressure difference between the cleaning liquid and the stock solution.
• Patent Document 4 discloses a technique for cleaning reverse osmosis membranes and nanofiltration membranes with an iodine compound.
• Patent Document 5 discloses a technique for regenerating a reverse osmosis membrane for producing ultrapure water by removing boron from a raw solution by passing hot water through the membrane.
• Patent Documents 1 to 5 relate to means for recovering performance degradation caused by fouling of a semipermeable membrane, scale generation on the semipermeable membrane, and the like, which are derived from solutes and insoluble matters contained in the raw liquid, in membrane separation of a raw liquid using water as a solvent.
• the present inventors have found that the performance of the semipermeable membrane is also deteriorated when the operation of membrane separation of a feed solution containing an organic solvent is continued for a long period of time, and further, the present inventors have found that the deterioration of the performance in this case cannot be restored by the conventionally known method for regenerating the semipermeable membrane.
• An object of the present invention is to provide a method for regenerating a semipermeable membrane whose performance has deteriorated due to continued operation in membrane separation of a feed solution containing an organic solvent as a solvent.
• membrane separation of a feed solution containing an organic solvent there has hitherto been no known method for regenerating a semipermeable membrane whose performance has deteriorated due to continued operation.
• the present invention is as follows:
• a method for regenerating a semipermeable membrane comprising the steps of: The semipermeable membrane has a history of contact with a liquid containing an organic solvent,
• the regeneration method includes contacting the semipermeable membrane with a regenerant; and
• the regenerant is selected from a liquid containing water at 50° C. or higher and a gas containing water at 80° C. or higher. How to regenerate a semipermeable membrane.
• the separation functional layer comprises polyamide.
• ⁇ Aspect 8> The method for regenerating a forward osmosis membrane according to aspect 4, wherein the regenerant is water at a temperature of 70°C or higher and 100°C or lower.
• ⁇ Aspect 9>> The method for regenerating a semipermeable membrane according to aspect 1, wherein the contact time between the semipermeable membrane and the regenerator is from 2 minutes to 10 hours.
• ⁇ Aspect 10> The method for regenerating a semipermeable membrane according to aspect 5, wherein the contact time between the semipermeable membrane and the regenerator is from 2 minutes to 10 hours.
• a treatment agent selected from a water-containing liquid at 50°C or higher and a water-containing gas at 80°C or higher before contacting the liquid.
• the semipermeable membrane is a forward osmosis membrane
• the forward osmosis performance value (F/R), which is expressed as the ratio of the salt back diffusion amount (R, unit: g/( m2 ⁇ hr)) to the water permeability (F, unit: kg/( m2 ⁇ hr))
• F/R forward osmosis performance value
• the semipermeable membrane is a forward osmosis membrane
• the forward osmosis performance value which is expressed as the ratio of the salt back diffusion amount (R, unit: g/( m2 ⁇ hr)) to the water permeability (F, unit: kg/( m2 ⁇ hr)
• F/R forward osmosis performance value
• a method for regenerating a semipermeable membrane comprising the steps of:
• the regeneration method includes an organic solvent removal step of removing the organic solvent from a liquid containing the organic solvent through a semipermeable membrane, After the organic solvent removal step, a regeneration step of contacting the semipermeable membrane with a regenerant is included;
• the regenerant is selected from a liquid containing water at 50° C. or higher and a gas containing water at 80° C. or higher. How to regenerate a semipermeable membrane.
• Aspect 19 The method for regenerating a semipermeable membrane according to aspect 18, wherein the semipermeable membrane has a support membrane and a separation functional layer.
• Aspect 20 The method for regenerating a semipermeable membrane according to aspect 19, wherein the separation functional layer comprises polyamide.
• the present invention provides a method for regenerating a semipermeable membrane whose performance has deteriorated due to continued operation in membrane separation of a raw liquid containing an organic solvent.
• present embodiment an embodiment of the present invention
• present invention is not limited to the present embodiment.
• present invention can be modified in various ways without departing from the gist of the invention.
• a method of regenerating a semipermeable membrane includes contacting the semipermeable membrane with a regenerant; and The regenerant is selected from a liquid containing water and having a temperature of 50° C. or higher and a gas containing water and having a temperature of 80° C. or higher. This is the method.
• a method for regenerating a semipermeable membrane comprising: an organic solvent removal step of removing the organic solvent from the liquid containing the organic solvent through a semipermeable membrane; After the organic solvent removal step, a regeneration step of contacting the semipermeable membrane with a regenerant is included; The method for regenerating a semipermeable membrane is provided, wherein the regenerant is selected from a liquid containing water at 50° C. or higher and a gas containing water at 80° C. or higher.
• the methods for regenerating a semipermeable membrane according to the first and second embodiments described above may be interchangeable in terms of steps or components, or the steps or components according to both embodiments may be combined.
• the components and steps common to both embodiments, as well as the components and steps preferred for both embodiments, are described below.
• the method for regenerating a semipermeable membrane may include a pre-washing treatment in which the semipermeable membrane is contacted with water at less than 50°C before contacting the semipermeable membrane with the regenerant.
• the semipermeable membrane to which the regeneration method for semipermeable membranes is applied is, for example, a semipermeable membrane whose performance has deteriorated due to continued operation in membrane separation of a raw liquid containing an organic solvent as a solvent.
• membrane separation it is considered that the membrane performance deteriorates when the semipermeable membrane comes into contact with the organic solvent and interacts with it, causing the molecular structure of the semipermeable membrane to "loosen.”
• the organic solvent solvates in the separation functional layer of the semipermeable membrane, causing the separation functional layer to swell, resulting in a deterioration in membrane performance.
• the semipermeable membrane whose membrane performance has deteriorated due to contact with an organic solvent, is contacted with a regenerant selected from a water-containing liquid at 50°C or higher and a water-containing gas at 80°C or higher, thereby removing the organic solvent in the semipermeable membrane and stabilizing the molecular structure of the semipermeable membrane, thereby regenerating the semipermeable membrane.
• a regenerant selected from a water-containing liquid at 50°C or higher and a water-containing gas at 80°C or higher
• the semipermeable membrane to which the regeneration method according to the present embodiment is applied may be one whose molecular structure is "loosened” upon contact with an organic solvent. Therefore, the semipermeable membrane may include a portion at least partially composed of an organic material.
• the organic material constituting at least a part of the semipermeable membrane in this embodiment include polyolefins, polysulfones, polyethersulfones, cellulose acetate, polyacrylonitrile, polyacrylic acid esters, polymethacrylic acid esters, polyesters, polyamides, ceramics, and fluorine-based resins, and the organic material may be one or more selected from these.
• the semipermeable membrane in this embodiment may be a semipermeable membrane having a support membrane and a separation functional layer.
• the separation functional layer does not have to be located directly above the support membrane, as long as it is on the semipermeable membrane surface that is exposed to water vapor, or it may be located directly above the support membrane.
• the semipermeable membrane may be composed of a support membrane and a separation functional layer, and the separation functional layer may be located on one or both sides of the support membrane, or there may be a single layer or multiple layers between the support membrane and the separation functional layer.
• Materials constituting the support film include, for example, polyethersulfone, polysulfone, polyketone, polyetheretherketone, polyphenylene ether, polyvinylidene fluoride, polyacrylonitrile, polyimine, polyimide, polybenzoxazole, polybenzimidazole, sulfonated tetrafluoroethylene, polyamide, etc., and it is preferable to use one or more types selected from the group consisting of these.
• the separation functional layer preferably contains polyamide, and more preferably consists of polyamide.
• a separation functional layer consisting of polyamide can be formed, for example, by performing interfacial polymerization of a polyfunctional acid halide and a polyfunctional aromatic amine on a support membrane, or by positioning a separation functional layer consisting of polyamide so that it becomes the surface of the semipermeable membrane.
• a polyfunctional aromatic acid halide is an aromatic acid halide compound having two or more acid halide groups in one molecule.
• Specific examples include trimesic acid halide, trimellitic acid halide, isophthalic acid halide, terephthalic acid halide, pyromellitic acid halide, benzophenonetetracarboxylic acid halide, biphenyldicarboxylic acid halide, naphthalenedicarboxylic acid halide, pyridinedicarboxylic acid halide, and benzenedisulfonic acid halide, and these can be used alone or in mixtures.
• halide ions in these aromatic acid halide compounds include chloride ions, bromide ions, and iodide ions.
• trimesic acid chloride alone, a mixture of trimesic acid chloride and isophthalic acid chloride, or a mixture of trimesic acid chloride and terephthalic acid chloride is preferably used.
• the polyfunctional aromatic amine is an aromatic amino compound having two or more amino groups in one molecule.
• Specific examples include m-phenylenediamine, p-phenylenediamine, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylamine, 4,4'-diaminodiphenylether, 3,4'-diaminodiphenylether, 3,3'-diaminodiphenylamine, 3,5-diaminobenzoic acid, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 1,3,5-triaminobenzene, and 1,5-diaminonaphthalene, and these can be used alone or in mixtures.
• one or more selected from m-phenylenediamine and p-phenylenediamine are particularly preferably used.
• the interfacial polymerization of the polyfunctional acid halide and the polyfunctional aromatic amine can be carried out according to a conventional method.
• the semipermeable membrane to which the regeneration method according to this embodiment is applied may have a history of contact with a treatment agent selected from a water-containing liquid at 50°C or higher and a water-containing gas at 80°C or higher before contacting with a liquid containing an organic solvent. If the semipermeable membrane has a history of contact with such a treatment agent, the molecular structure is less likely to loosen when it comes into contact with a liquid containing an organic solvent, and the frequency of carrying out the regeneration method according to the present embodiment can be reduced. In particular, in the case of a semipermeable membrane having a support membrane and a separation functional layer on the support membrane, there is an advantage that the molecular structure of the separation functional layer becomes robust by contact with the treatment agent. When the semipermeable membrane has no history of contact with the above-mentioned treatment agent, application of the regeneration method according to this embodiment may improve the membrane performance of the semipermeable membrane compared to the initial performance.
• a treatment agent selected from a water-containing liquid at 50
• the semipermeable membrane to which the regeneration method according to this embodiment is applied may be, for example, a microfiltration membrane, an ultrafiltration membrane, a nanofiltration membrane, a reverse osmosis membrane, a forward osmosis membrane, or the like, and in particular may be a forward osmosis membrane.
• the semipermeable membrane may have any structure, for example, a hollow fiber membrane, a tubular membrane, or a flat membrane.
• the semi-permeable membrane may be in the form of a membrane module, which comprises a plurality of semi-permeable membranes housed within a suitable housing.
• the semipermeable membrane to which the regeneration method according to the present embodiment is applied has a history of contact with a liquid containing an organic solvent, i.e., the semipermeable membrane to which the regeneration method according to the present embodiment is applied is a semipermeable membrane that has been used for membrane separation of a raw liquid containing an organic solvent as at least a part of the solvent.
• the organic solvent contained in the liquid may be one or more selected from, for example, aliphatic hydrocarbons, aromatic hydrocarbons, ketones, ethers, alcohols, carboxylic acids, aldehydes, nitrile compounds, amide compounds, halogenated hydrocarbons, sulfoxide compounds, ester compounds, and the like.
• Examples of aliphatic hydrocarbons include propane, butane, pentane, hexane, heptane, octane, decane, undecane, and cyclooctane;
• aromatic hydrocarbons include benzene, toluene, xylene, biphenyl, pyridine, and pyrrole;
• ketones include acetone, methyl ethyl ketone, diethyl ketone, methyl propyl ketone, methyl isobutyl ketone, methyl amyl ketone, cyclohexanone, acetophenone, and benzophenone;
• Examples of ethers include dimethyl ether, ethyl methyl ether, diethyl ether, diphenyl ether, ethylene oxide, tetrahydrofuran, 1,4-dioxane, and anisole;
• Examples of alcohols include methanol, ethanol, 1-propan
• the organic solvent contained in the liquid may be a hydrophilic organic solvent, which may be, for example, one or more selected from alcohols having 1 to 3 carbon atoms and nitrile compounds, and may be one or more selected from methanol, ethanol, 1-propanol, 2-propanol, and acetonitrile.
• the liquid may be an aqueous solution containing a hydrophilic organic solvent.
• the content of the hydrophilic organic solvent in the liquid may be 1% by mass or more, 5%, 10%, 20%, 40%, or 50% by mass or more, based on the total mass of the liquid.
• the content of the hydrophilic organic solvent in the liquid is 5% by mass or more, the performance of the semipermeable membrane is likely to decrease, so that the effect of applying the regeneration method according to the present embodiment can be more greatly enjoyed.
• the content of the hydrophilic organic solvent in the liquid may be less than 100% by mass, 95% by mass or less, 90% by mass or less, 85% by mass or less, or 80% by mass or less.
• the semipermeable membrane to which the regeneration method according to the present embodiment is applied has its membrane performance deteriorated due to contact with a liquid containing an organic solvent.
• the degree of deterioration in membrane performance can be estimated by the forward osmosis performance value (F/R), which is expressed as the ratio of the salt back diffusion amount (R, unit: g/( m2 ⁇ hr)) to the water permeability (F, unit: kg/( m2 ⁇ hr)).
• the forward osmosis performance value (F/R), which is expressed as the ratio of the salt back diffusion amount (R, unit: g/( m2 x hr)) to the water permeability (F, unit: kg/( m2 x hr)), is 0.90 times or less compared to the forward osmosis performance value (initial forward osmosis performance value) ( F0 / R0 ) when the semipermeable membrane has no history of contact with the liquid, the benefits of the present invention can be effectively enjoyed.
• the semipermeable membrane to which the regeneration method according to this embodiment is applied may have a forward osmosis performance value (F/R) that is 0.10 times or more, or 0.20 times or more, compared to the initial forward osmosis performance value (F 0 /R 0 ).
• the regeneration method according to the present embodiment includes contacting a semipermeable membrane whose membrane performance has been reduced by contact with a liquid containing an organic solvent with at least one regenerant selected from a water-containing liquid at 50° C. or higher and a water-containing gas at 80° C. or higher.
• the semipermeable membrane whose membrane performance has been reduced is contacted with a regenerant selected from a water-containing liquid at 50° C. or higher or a water-containing gas at 80° C. or higher.
• a pre-cleaning treatment may be performed in which the semipermeable membrane is brought into contact with water at a temperature of less than 50° C. before the semipermeable membrane is brought into contact with the regenerant.
• the organic solvent can be more easily removed from the semipermeable membrane by carrying out a pre-cleaning treatment.
• the temperature of the water in the pre-washing treatment may be 45° C. or less, 40° C. or less, or 30° C. or less, and may be 0° C. or more, 10° C. or more, or 15° C. or more, and may typically be room temperature.
• the contact of the semipermeable membrane with water in the pre-cleaning treatment may be any of an immersion method in which the semipermeable membrane is immersed in water, a forward washing method in which water is passed through the semipermeable membrane from the stock solution side to the opposite side, and a backwashing method in which water is passed through the semipermeable membrane from the opposite side to the stock solution side to the stock solution side, and two or more of these may be performed sequentially.
• the time for the pre-cleaning treatment may be 10 minutes or more, 30 minutes or more, or 1 hour or more, and may be 24 hours or less, 12 hours or less, 8 hours or less, 6 hours or less, 4 hours or less, or 2 hours or less.
• the above pre-cleaning treatment time is the time for each of the immersion method, the forward washing method, and the backwashing method.
• a process of drying the semipermeable membrane by flowing dry air through it may be performed before contacting the semipermeable membrane with the regenerant.
• the regeneration method according to the present embodiment includes contacting a semipermeable membrane whose membrane performance has been reduced by contact with a liquid containing an organic solvent with a regenerant selected from a water-containing liquid at 50° C. or higher and a water-containing gas at 80° C. or higher.
• the semipermeable membrane whose membrane performance has been reduced may be contacted with a regenerant selected from a water-containing liquid at 50° C. or higher or a water-containing gas at 80° C. or higher.
• the water-containing liquid as the regenerant does not need to contain an organic solvent.
• the water-containing liquid may contain a solute.
• the solute include sodium chloride, magnesium chloride, and chlorine. Therefore, the aqueous liquid may be water or an aqueous solution containing the above-mentioned solute.
• the electrical conductivity of the water-containing liquid may be 500 ⁇ S/cm or less, and preferably water having a purity equal to or higher than that of purified water prescribed in the Japanese Pharmacopoeia may be used.
• the temperature of the liquid containing water as a regenerant is 50° C. or higher, and may be 60° C. or higher, 70° C. or higher, 80° C. or higher, 90° C. or higher, 95° C. or higher, or 100° C. or higher, from the viewpoint of removing the organic solvent in the semipermeable membrane and effectively stabilizing the molecular structure of the semipermeable membrane.
• the temperature of the liquid may be 140° C. or less, 130° C. or less, 120° C. or less, 110° C. or less, or 100° C. or less.
• the temperature of the liquid may be equal to or less than the boiling point of the liquid. Note that the boiling point of the liquid may vary depending on the amount of solute contained in the liquid, the pressure, etc.
• the contact between the semipermeable membrane and the liquid containing water may be any of an immersion method in which the semipermeable membrane is immersed in the liquid, a forward washing method in which a liquid is passed through the semipermeable membrane from the stock liquid side to the opposite side, and a backwash method in which a liquid is passed through the semipermeable membrane from the opposite side to the stock liquid side to the stock liquid side, and two or more of these may be performed sequentially.
• the contact time between the semipermeable membrane and the liquid containing water may be 30 minutes or more, 45 minutes or more, 1 hour or more, or 2 hours or more, and may be 24 hours or less, 12 hours or less, 8 hours or less, 6 hours or less, or 4 hours or less.
• the type of water-containing gas used as the regenerant is not particularly limited, but from the viewpoint of ease of handling, water vapor is preferred.
• the temperature of the gas containing water as a regenerant is, from the viewpoint of removing the organic solvent in the semipermeable membrane and effectively stabilizing the molecular structure of the semipermeable membrane, 80° C. or more, and may be 90° C. or more, 100° C. or more, more than 100° C., 110° C. or more, or 120° C. or more, and may be 150° C. or less, 140° C. or less, 135° C. or less, 130° C. or less, or 125° C. or less, from the viewpoint of thermal efficiency during heating.
• the gas containing water as a regenerant is preferably superheated steam having a temperature of more than 100° C., from the viewpoint of the regeneration efficiency of the semipermeable membrane.
• the contact between the semipermeable membrane and the water-containing gas may be any of a static method in which the semipermeable membrane is placed in a sealed container, and gas is supplied into the container and allowed to stand; a forward washing method in which gas is passed through the semipermeable membrane from the raw liquid side to the opposite side; and a backwash method in which gas is passed through the semipermeable membrane from the opposite side to the raw liquid side to the raw liquid side, and two or more of these may be performed sequentially.
• the contact time between the semipermeable membrane and the water-containing gas may be 2 minutes or more, 5 minutes or more, 10 minutes or more, 20 minutes or more, 30 minutes or more, or 45 minutes or more, and may be 10 hours or less, 8 hours or less, 6 hours or less, 4 hours or less, or 2 hours or less.
• the above contact time is the time for each of the standing method, forward washing method, and backwashing method.
• the semipermeable membrane whose membrane performance has been deteriorated due to contact with a liquid containing an organic solvent can have its membrane performance restored by applying the regeneration method of the present invention.
• the degree of recovery of membrane performance can be such that the forward osmosis performance value after recovery (F/R) is 0.85 times or more as compared with the forward osmosis performance value (initial forward osmosis performance value) ( F0 / R0 ) when the semipermeable membrane has no history of contact with a liquid containing an organic solvent.
• the forward osmosis performance value (F/R) after regeneration can be 0.90 times or more, 0.95 times or more, 0.98 times or more, or 0.99 times or more, compared to the initial forward osmosis performance value (F 0 /R 0 ), and can also be 1.00 times.
• the membrane performance of the semipermeable membrane may be improved from the initial performance by applying the regeneration method of the present invention.
• the forward osmosis performance value (F/R) after regeneration can be increased to about 1.00 times or more and 1.20 times or less compared to the initial forward osmosis performance value (F 0 /R 0 ).
• the water permeability (F) and the salt back-diffusion rate (R) are expressed by the following formulas (1) and (2), respectively:
• F L / (M ⁇ H) (1)
• L is the amount of water (kg) that has permeated the forward osmosis membrane
• M is the effective surface area of the forward osmosis membrane (m2)
• H is time (hr).
• R G / (M ⁇ H) (2)
• G the amount of salt (kg) that has permeated the forward osmosis membrane
• M is the effective surface area of the forward osmosis membrane (m 2 )
• H time (hr). ⁇ It was calculated by:
• a forward osmosis performance value (F/R), which is expressed as the ratio of the salt back diffusion amount (R) to the water permeability (F), was calculated and used as an index of forward osmosis performance. It can be seen that the larger the forward osmosis performance value (F/R), the more excellent the forward osmosis performance of the forward osmosis membrane module.
• F/R forward osmosis performance value
• the water permeability (F) and salt back-diffusion rate (R) of the module were measured under the following conditions.
• Purified water was used as the stock solution, and an aqueous solution of sodium chloride with a concentration of 3.5% by mass was used as the draw solution.
• the stock solution was circulated in the space inside (the separation functional layer side) of the hollow fibers of the forward osmosis membrane module, and the draw solution was circulated in the space outside so that the flow directions of both solutions were parallel, and the draw solution side was pressurized to a pressure of 20 kPaG to perform forward osmosis treatment for 20 minutes.
• the sodium chloride concentration in the draw solution was tracked, and a saturated aqueous solution of sodium chloride was appropriately dropped to maintain the sodium chloride concentration in the draw solution constant.
• the temperatures of the stock solution and the induction solution were both set to 25° C., and the linear velocities of the stock solution and the induction solution on the surface of the hollow fiber membrane were both set to 3.0 cm/sec.
• acetonitrile aqueous solution 15% by weight acetonitrile aqueous solution (MeCN 15%) 50% by weight acetonitrile aqueous solution (MeCN50%) Ethanol (EtOH) Toluene Ethyl Acetate
• the acetonitrile used was a 99.5% pure product manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.
• the ethanol used was a 99.5% pure product manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.
• the toluene used was a 99.5% pure product manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.
• the ethyl acetate used was a 99.5% pure product manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.
• Purified water was used as the solvent (water) for the aqueous solution.
• Both the inner and outer spaces of the hollow fibers in the forward osmosis membrane module were filled with a liquid containing an organic solvent, and the module was left to stand at 25° C. for 168 hours to carry out a contact treatment.
• the module was held so that its axial direction was approximately vertical, and the liquid containing the organic solvent was drained by gravity from the liquid inlet/outlet at the bottom of the module.
• water was circulated through both the inner and outer spaces of the hollow fibers in the forward osmosis membrane module to wash the forward osmosis membrane. After washing with water, the module was subjected to measurement of the water permeability (F) and the amount of salt back diffusion (R).
• Example 1 The forward osmosis membrane housed in the hollow fiber forward osmosis membrane module in Example 1 was a forward osmosis membrane that used a hollow fiber membrane made of polysulfone (PSf) as a hollow fiber porous support membrane and had a separation functional layer made of polyamide on the inner surface of the hollow fiber membrane.
• the hollow fiber forward osmosis membrane module of Example 1 was produced as follows.
• spinning dope a uniform polymer solution (spinning dope) consisting of 19% by mass of polysulfone (Solvay Specialty Polymers, Udel-P3500), 61% by mass of N-methyl-2-pyrrolidone (Fujifilm Wako Pure Chemical Industries, Ltd.), and 20% by mass of tetraethylene glycol (Tokyo Chemical Industry Co., Ltd.) was prepared.
• the spinning dope was filled into a wet hollow fiber spinning machine equipped with a double spinneret.
• the spinning dope was discharged from the outer spinneret of the double spinneret and the internal coagulation liquid (water) was discharged from the inner spinneret, and the dope was introduced into a coagulation bath filled with water as the external coagulation liquid to coagulate, thereby obtaining a hollow fiber fibrous porous support membrane.
• the obtained hollow fiber porous support membrane had an outer diameter of 1.00 mm, an inner diameter of 0.60 mm, and a membrane thickness of 0.20 mm.
• the internal space of this supported membrane module was divided into two by the membrane wall of the hollow fibers, and the two spaces were fluidically isolated except for the passage of liquid through the membrane wall.
• the housing had liquid inlets and outlets (liquid inlet and liquid outlet) communicating with the space inside the hollow fibers, and liquid inlets and outlets (liquid inlet and liquid outlet) communicating with the space outside the hollow fibers.
• the space outside the hollow fiber of the support membrane module was reduced in pressure to 90 kPaG and this reduced pressure state was maintained for 1 minute. After that, air was circulated through the space inside the hollow fiber for 1 minute to remove excess first solution.
• an n-hexane solution (second solution) containing 0.20% by mass of trimesoyl chloride (TMC) was passed through the space inside the hollow fibers of the support membrane module at a flow rate of 40 mL/min for 2 minutes to carry out interfacial polymerization, thereby forming a polyamide layer on the inner surface of the hollow fibers.
• nitrogen was circulated through the space inside the hollow fibers for 1 minute to remove excess second solution, and then water at 70°C was circulated through the space inside the hollow fibers for 20 minutes to wash the inner surface of the hollow fibers.
• the module was placed in an autoclave (SX-500, manufactured by Tommy Seiko Co., Ltd.) Superheated steam at 121° C. was circulated in the autoclave for 20 minutes to cure the polyamide layer.
• water was circulated through the space inside the hollow fibers of the module for 30 minutes to clean the surface of the polyamide layer after the wet heat treatment.
• a 15% by mass aqueous acetonitrile solution (MeCN 15%) was used as the liquid containing an organic solvent, and the hollow fiber forward osmosis membrane module after the initial F/R measurement was contacted with the liquid containing an organic solvent by the above-mentioned method, and then the water permeability (F) and the salt back diffusion amount (R) were measured, and the forward osmosis performance value (F/R) (F/R after contact with the organic solvent) was calculated.
• the module after contact with the liquid containing the organic solvent was subjected to a regeneration treatment using superheated steam as a regenerant by the following method.
• the module after contact with the liquid containing the organic solvent was placed in an autoclave (SX-500, manufactured by Tommy Seiko Co., Ltd.) with the two liquid inlets and outlets open.
• Superheated steam at 121°C was circulated in the autoclave for one hour to carry out a regeneration treatment.
• water at 25°C was circulated for 30 minutes into the spaces both inside and outside the hollow fibers of the module to wash both surfaces of the hollow fibers after the regeneration treatment, thereby completing the regeneration treatment.
• the water permeability (F) and salt back diffusion rate (R) were measured by the above-mentioned method, and the forward osmosis performance value (F/R) (F/R after regeneration treatment) was calculated.
• the ratio of F/R after the regeneration treatment to the initial F/R value was expressed as a percentage and evaluated as the "performance recovery rate.” The evaluation results are shown in Table 1.
• Example 2 The evaluation was carried out in the same manner as in Example 1, except that 50% MeCN was used as the liquid containing the organic solvent. The evaluation results are shown in Table 1.
• Example 3 The forward osmosis membrane housed in the hollow fiber forward osmosis membrane module in Example 3 was a forward osmosis membrane that used a hollow fiber membrane made of polyketone (PK) as a hollow fiber porous support membrane and had a separation functional layer made of polyamide on the inner surface of the hollow fiber membrane.
• PK polyketone
• a hollow fiber-shaped forward osmosis membrane module was produced in the same manner as in the Examples, except that a hollow fiber-shaped porous support membrane and a support membrane module made of polyketone (PK) were produced as follows.
• the spinning stock solution was discharged from the outer spinneret of the double spinneret and the internal coagulation liquid (water) was discharged from the inner spinneret, and the spinning stock solution was introduced into a coagulation bath filled with a 40% by mass aqueous methanol solution as the external coagulation liquid to obtain a hollow fiber fibrous porous support membrane.
• the obtained hollow fiber porous support membrane had an outer diameter of 0.60 mm, an inner diameter of 0.35 mm, and a membrane thickness of 0.125 mm.
• Example 4 The forward osmosis membrane housed in the hollow fiber forward osmosis membrane module in Example 4 is a forward osmosis membrane that uses a hollow fiber membrane made of polyethersulfone (PES) as a hollow fiber porous support membrane and has a separation functional layer made of polyamide on the inner surface of the hollow fiber membrane.
• a hollow fiber forward osmosis membrane module was produced in the same manner as in the Examples, except that a hollow fiber porous support membrane and a support membrane module made of polyethersulfone (PES) were produced as follows.
• polyethersulfone 55 parts by mass of BASF's product name "Ultrason E 2020 P” and 45 parts by mass of hydroxylated polyethersulfone (BASF's product name "Ultrason E 2020 P SR”) were mixed and used. These polymer mixtures were dissolved in N-methyl-2-pyrrolidone (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) to prepare a polymer solution (spinning stock solution) with a polymer concentration of 18.5% by mass. The spinning stock solution was filled into a wet hollow fiber spinning machine equipped with a double spinneret.
• N-methyl-2-pyrrolidone manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.
• the spinning stock solution was discharged from the outer spinneret of the double spinneret and the internal coagulation liquid (water) was discharged from the inner spinneret, respectively, and introduced into a coagulation bath filled with water as the external coagulation liquid to coagulate, thereby obtaining a hollow fiber fibrous porous support membrane.
• the obtained hollow fiber porous support membrane had an outer diameter of 1.0 mm, an inner diameter of 0.70 mm, and a membrane thickness of 0.15 mm.
• Example 5 The evaluation was carried out in the same manner as in Example 1, except that EtOH was used as the liquid containing the organic solvent. The evaluation results are shown in Table 1.
• Example 6 The evaluation was carried out in the same manner as in Example 1, except that regeneration treatment using hot water as a regenerant was carried out in the following manner instead of the regeneration treatment using superheated steam.
• the evaluation results are shown in Table 1.
• the procedure for regeneration treatment using hot water is as follows. After contact with the liquid containing the organic solvent, hot water at a temperature of 85° C. was circulated through the space inside the hollow fibers of the module at a flow rate of 100 mL/min for 0.5 hours to carry out a regeneration treatment. Thereafter, water at 85° C. was circulated through the space inside the hollow fibers of the module for 30 minutes to wash the inner surfaces of the hollow fibers after the regeneration treatment, thereby completing the regeneration treatment.
• Example 7 The evaluation was performed in the same manner as in Example 6, except that the type of liquid containing an organic solvent, and the temperature and flow time of the hot water were each as shown in Table 1. The evaluation results are shown in Table 1.
• Comparative Example 1 The evaluation was carried out in the same manner as in Example 6, except that the regeneration treatment was carried out using water at 25° C. instead of hot water and the flow time was set to 24 hours. The evaluation results are shown in Table 1.
• Example 9 Evaluation was carried out in the same manner as in Example 3, except that toluene was used as the liquid containing an organic solvent, and the module after contact was dried by flowing dry air through it. The evaluation results are shown in Table 2.
• Example 10 The evaluation was carried out in the same manner as in Example 9, except that ethyl acetate was used as the liquid containing an organic solvent, and the module after contact was dried by flowing dry air through it. The evaluation results are shown in Table 2.
• Example 11 The module was evaluated in the same manner as in Example 5, except that after contact with EtOH as a liquid, the module was dried by flowing dry air through it. The evaluation results are shown in Table 2.

Landscapes

• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Separation Using Semi-Permeable Membranes (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=91378954

Family Applications (1)

Country Status (3)

Citations (11)

Family Cites Families (3)

• 2023
  • 2023-12-06 EP EP23900678.6A patent/EP4631608A4/en active Pending
  • 2023-12-06 JP JP2024562958A patent/JPWO2024122564A1/ja active Pending
  • 2023-12-06 WO PCT/JP2023/043587 patent/WO2024122564A1/ja not_active Ceased

Patent Citations (12)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events