WO1993002782A1 - Membrane structure for osmotic concentration - Google Patents

Membrane structure for osmotic concentration Download PDF

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Publication number
WO1993002782A1
WO1993002782A1 PCT/AU1992/000396 AU9200396W WO9302782A1 WO 1993002782 A1 WO1993002782 A1 WO 1993002782A1 AU 9200396 W AU9200396 W AU 9200396W WO 9302782 A1 WO9302782 A1 WO 9302782A1
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WO
WIPO (PCT)
Prior art keywords
membrane
water
membrane structure
sheet
osmotic concentration
Prior art date
Application number
PCT/AU1992/000396
Other languages
French (fr)
Inventor
Alan Sherman Michaels
Original Assignee
Nonap Pty. Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nonap Pty. Ltd. filed Critical Nonap Pty. Ltd.
Publication of WO1993002782A1 publication Critical patent/WO1993002782A1/en

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Classifications

    • 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
    • B01D69/1213—Laminated layers
    • 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
    • A—HUMAN NECESSITIES
    • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23L—FOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
    • A23L2/00—Non-alcoholic beverages; Dry compositions or concentrates therefor; Their preparation
    • A23L2/70—Clarifying or fining of non-alcoholic beverages; Removing unwanted matter
    • A23L2/72—Clarifying or fining of non-alcoholic beverages; Removing unwanted matter by filtration
    • A23L2/74—Clarifying or fining of non-alcoholic beverages; Removing unwanted matter by filtration using membranes, e.g. osmosis, ultrafiltration
    • 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
    • B01D61/36—Pervaporation; Membrane distillation; Liquid permeation
    • 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
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12H—PASTEURISATION, STERILISATION, PRESERVATION, PURIFICATION, CLARIFICATION OR AGEING OF ALCOHOLIC BEVERAGES; METHODS FOR ALTERING THE ALCOHOL CONTENT OF FERMENTED SOLUTIONS OR ALCOHOLIC BEVERAGES
    • C12H1/00—Pasteurisation, sterilisation, preservation, purification, clarification, or ageing of alcoholic beverages
    • C12H1/12—Pasteurisation, sterilisation, preservation, purification, clarification, or ageing of alcoholic beverages without precipitation
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12H—PASTEURISATION, STERILISATION, PRESERVATION, PURIFICATION, CLARIFICATION OR AGEING OF ALCOHOLIC BEVERAGES; METHODS FOR ALTERING THE ALCOHOL CONTENT OF FERMENTED SOLUTIONS OR ALCOHOLIC BEVERAGES
    • C12H3/00—Methods for reducing the alcohol content of fermented solutions or alcoholic beverage to obtain low alcohol or non-alcoholic beverages
    • C12H3/04—Methods for reducing the alcohol content of fermented solutions or alcoholic beverage to obtain low alcohol or non-alcoholic beverages using semi-permeable membranes

Definitions

  • This invention relates to a membrane arrangement for use in the osmotic concentration of aqueous solutions.
  • osmotic concentration of aqueous solutions is in the concentration of juices and beverages.
  • a desirable membrane structure for use in the osmotic concentration of aqueous solutions via osmotic transfer of water to concentrated aqueous saline solutions is a microporous, non-water-wettable membrane, contacted on its opposite surfaces by the solution to be concentrated and the brine into which the water is to be transferred.
  • the membrane operates such that the pores thereof are filled only with water vapour, and water transport occurs only by molecular transport through the vapour phase.
  • Membranes of such properties are well-known to those skilled in the membrane art, and include microporous structures fabricated from poly tetrafluorethylene, for example GORE-TEX (trade mark of W.L. Gore & Associates, Inc.), from polypropylene, for example CELGARD (Registered Trade Mark), ACCUREL (Registered Trade Mark) and the like.
  • Contaminants or other components present in the feed liquid which are likely to cause this problem include emulsified oil droplets, colloidal hydrogel particles, proteins and other biological macromolecules, and surface active agents. These components are, for the most part, non-volatile under the conditions of osmotic concentration, with the result that they remain behind in the feed liquid and may preferentially and adversely accumulate at the upstream membrane surface.
  • Components of solutions used to clean membrane devices often contain surface active agents, and that residual from these solutions, rather than feed components, might also promote membrane wetting.
  • the invention provides a membrane structure for use in the osmotic concentration of liquids, said structure including a water-permeable sheet attached to a non-water- wettable, microporous membrane.
  • the invention also provides a membrane structure for use in the osmotic concentration of liquids, wherein the feed liquid contains volatile and/or fragrance and/or flavour components, said structure including a liquid impermeable but vapour permeable sheet or film associated with a non-wettable membrane, said sheet separating said feed liquid from said membrane.
  • the invention further provides an osmotic concentration method, using the membrane structure of either of the two preceding paragraphs.
  • a barrier film which is substantially freely permeable to water (and which may be permeable also to other microsolutes present), but which is essentially impermeable to macrosolutes and colloids. If such a barrier were deposited on the feed-liquid side of the membrane, then none of the wettabil ⁇ ty-altering components of the feed solution would contact the membrane surface, but water transporting across that barrier would be free to evaporate and migrate through the vapour-filled membrane pores and condense in the brine on the opposite surface.
  • any (non-volatile) microsolutes such as sugar, which can migrate into the barrier layer, will be concentrated at the layer/membrane boundary, and must then migrate by molecular diffusion back through the barrier into the feed solution.
  • this barrier film be as thin as possible, commensurate with the rate of transport of water from the feed liquid into the brine.
  • the membrane structure could be a laminate comprising the microporous membrane described hereinabove with a thin, hydrophilic gel- type membrane of high intrinsic water-permeability but very low permeability to macrosolutes.
  • a thin, hydrophilic gel- type membrane of high intrinsic water-permeability but very low permeability to macrosolutes.
  • dialysis grade cellophane or CUPROPHAN (Registered Trade Mark) as is used in the fabrication of hemodialyzers.
  • This film might simply be laid on the surface of the microporous membrane, and the assembly mounted in the same module as is currently used for osmotic concentration.
  • Cellophane membranes as thin as 12.5 microns (0.5 mil) are commercially available, and would probably be suitable for this purpose.
  • hydrogel-film-side of the laminate be in contact with the feed liquid or solution to be concentrated.
  • a hydrogel film for fabrication of such a laminate is an asymmetric, ultramicroporous, water-wettable membrane, such as an ultrafiltration membrane, the pore size of which is too small to admit the objectionable macrosolutes or colloids.
  • the film should be as thin as possible to minimise polarization within the film, and consequent impedance to water transport.
  • a number of commercially available asymmetric ultrafiltration membranes are useful for this purpose, including (but not limited to) those comprised of cellulose acetate, polyacrylonitrile, Dynel (trade mark), polycarbonate, polyamide, polysulfone, polyolefin, and polyvinylidene difluoride.
  • Yet another embodiment of such a laminate involves coating the microporous membrane with a solution of a highly water-permeable polymer in a volatile, non-wetting solvent which, upon evaporation, leaves a very thin (but defect-free) coating of that polymer on the membrane.
  • a highly water-permeable polymer in a volatile, non-wetting solvent which, upon evaporation, leaves a very thin (but defect-free) coating of that polymer on the membrane.
  • ESTANE Registered Trade Mark
  • film-forming coating formulations suitable for this purpose include (but are not limited to) (1) aqueous solutions of thermally curable or cross-linkable polymers such as polyvinyl alcohol/glyoxal; ammonium carboxymethylcellulose; zinc ammonium alginate; gelatin/formaldehyde; chitosan formate; (2) alcohol or acetone solutions of hydroxyethylated or hydroxypropylated cellulose esters or ethers; (3) alcohol solutions of polyhydroxyethyl methacrylate; and the like.
  • thermally curable or cross-linkable polymers such as polyvinyl alcohol/glyoxal; ammonium carboxymethylcellulose; zinc ammonium alginate; gelatin/formaldehyde; chitosan formate
  • alcohol or acetone solutions of hydroxyethylated or hydroxypropylated cellulose esters or ethers (3) alcohol solutions of polyhydroxyethyl methacrylate; and the like.
  • the membrane structure of this invention is an improvement on existing osmotic concentration structures, which will permit direct osmotic concentration processing of juices and beverages, with or without pulp, and without pretreatment.
  • the invention is considered to be additionally suitable for the processing of aqueous solution of surface active solutes which are volatile, such as ethyl alcohol, and flavor and fragrance components such as aliphatic and aromatic esters, ethers, ketone, alcohols, and aldehydes.
  • surface active solutes which are volatile, such as ethyl alcohol, and flavor and fragrance components such as aliphatic and aromatic esters, ethers, ketone, alcohols, and aldehydes.

Abstract

A membrane structure for osmotic concentration of aqueous solutions such as juices and other beverages, is constituted by a water-permeable sheet attached to a non-water-wettable microporous membrane. Preferably, the structure is in the form of a laminate in which the sheet is laid upon or bonded to the membrane.

Description

MEMBRANE STRUCTURE FOR OSMOTIC CONCENTRATION
This invention relates to a membrane arrangement for use in the osmotic concentration of aqueous solutions.
One use for osmotic concentration of aqueous solutions is in the concentration of juices and beverages.
A desirable membrane structure for use in the osmotic concentration of aqueous solutions via osmotic transfer of water to concentrated aqueous saline solutions, is a microporous, non-water-wettable membrane, contacted on its opposite surfaces by the solution to be concentrated and the brine into which the water is to be transferred. The membrane operates such that the pores thereof are filled only with water vapour, and water transport occurs only by molecular transport through the vapour phase. Membranes of such properties are well-known to those skilled in the membrane art, and include microporous structures fabricated from poly tetrafluorethylene, for example GORE-TEX (trade mark of W.L. Gore & Associates, Inc.), from polypropylene, for example CELGARD (Registered Trade Mark), ACCUREL (Registered Trade Mark) and the like.
In many instances, however, the proper functioning of such a membrane is prevented by the presence of contaminants or other components of the feed liquid which promote wetting of the membrane by that solution, and the subsequent penetration of the membrane pores by the wetting liquid. In such a situation, there may be leakage of the feed liquid into the brine-compartment, or of brine into the feed liquid.
Contaminants or other components present in the feed liquid which are likely to cause this problem include emulsified oil droplets, colloidal hydrogel particles, proteins and other biological macromolecules, and surface active agents. These components are, for the most part, non-volatile under the conditions of osmotic concentration, with the result that they remain behind in the feed liquid and may preferentially and adversely accumulate at the upstream membrane surface.
Components of solutions used to clean membrane devices often contain surface active agents, and that residual from these solutions, rather than feed components, might also promote membrane wetting.
It is an object of the invention to provide an improved membrane structure for osmotic concentration.
The invention provides a membrane structure for use in the osmotic concentration of liquids, said structure including a water-permeable sheet attached to a non-water- wettable, microporous membrane.
The invention also provides a membrane structure for use in the osmotic concentration of liquids, wherein the feed liquid contains volatile and/or fragrance and/or flavour components, said structure including a liquid impermeable but vapour permeable sheet or film associated with a non-wettable membrane, said sheet separating said feed liquid from said membrane.
The invention further provides an osmotic concentration method, using the membrane structure of either of the two preceding paragraphs.
Embodiments of the invention, which may be preferred, will be described in detail hereinafter.
The previously-described problem, of the proper function of the membrane used in osmotic concentration being prevented by wetting of the membrane taking place, is believed to be overcome by the present invention.
In one general embodiment, it is suggested to impose, between the feed liquid and the microporous hydrophobic membrane described herein above, a barrier film which is substantially freely permeable to water (and which may be permeable also to other microsolutes present), but which is essentially impermeable to macrosolutes and colloids. If such a barrier were deposited on the feed-liquid side of the membrane, then none of the wettabilϊty-altering components of the feed solution would contact the membrane surface, but water transporting across that barrier would be free to evaporate and migrate through the vapour-filled membrane pores and condense in the brine on the opposite surface.
Any (non-volatile) microsolutes, such as sugar, which can migrate into the barrier layer, will be concentrated at the layer/membrane boundary, and must then migrate by molecular diffusion back through the barrier into the feed solution. In order to minimize the additional resistance to water transport imposed by this back-transport of solutes (so called solute-polarization), it is desirable that this barrier film be as thin as possible, commensurate with the rate of transport of water from the feed liquid into the brine.
In one particular embodiment, the membrane structure could be a laminate comprising the microporous membrane described hereinabove with a thin, hydrophilic gel- type membrane of high intrinsic water-permeability but very low permeability to macrosolutes. One such likely candidate for this laminate is dialysis grade cellophane or CUPROPHAN (Registered Trade Mark) as is used in the fabrication of hemodialyzers. This film might simply be laid on the surface of the microporous membrane, and the assembly mounted in the same module as is currently used for osmotic concentration. Cellophane membranes as thin as 12.5 microns (0.5 mil) are commercially available, and would probably be suitable for this purpose. To be functional for this embodiment, it is essential that the hydrogel-film-side of the laminate be in contact with the feed liquid or solution to be concentrated. Any other hydrophilic polymer film of adequately high intrinsic water permeability and virtual impermeability to macrosolutes and colloids, which can be fabricated in sufficient thinness, is suitable for this purpose, such films including (but not limited to) those comprised of esters and ethers of cellulose; crosslinked gelatin; gelatinized starch; chitin; agar; alginic acid; crosslinked polyacrylamide; poly (hydroxyethyl) methacrylate; crosslinked polyvinyl alcohol; and the like.
In another embodiment, as an alternative to a hydrogel film for fabrication of such a laminate, is an asymmetric, ultramicroporous, water-wettable membrane, such as an ultrafiltration membrane, the pore size of which is too small to admit the objectionable macrosolutes or colloids. In this case also (since such membranes are permeable to microsolutes), the film should be as thin as possible to minimise polarization within the film, and consequent impedance to water transport. A number of commercially available asymmetric ultrafiltration membranes are useful for this purpose, including (but not limited to) those comprised of cellulose acetate, polyacrylonitrile, Dynel (trade mark), polycarbonate, polyamide, polysulfone, polyolefin, and polyvinylidene difluoride.
Yet another embodiment of such a laminate, involves coating the microporous membrane with a solution of a highly water-permeable polymer in a volatile, non-wetting solvent which, upon evaporation, leaves a very thin (but defect-free) coating of that polymer on the membrane. One class of polymers useful for this purpose are the hydrophilic thermoplastic polyurethanes, for example, ESTANE (Registered Trade Mark) which are soluble in such solvents as tetrahydrofuran, DMF, and N-methyl pyrrolidone, from which thin films are easily cast.
Other film-forming coating formulations suitable for this purpose include (but are not limited to) (1) aqueous solutions of thermally curable or cross-linkable polymers such as polyvinyl alcohol/glyoxal; ammonium carboxymethylcellulose; zinc ammonium alginate; gelatin/formaldehyde; chitosan formate; (2) alcohol or acetone solutions of hydroxyethylated or hydroxypropylated cellulose esters or ethers; (3) alcohol solutions of polyhydroxyethyl methacrylate; and the like.
It can be seen that the membrane structure of this invention is an improvement on existing osmotic concentration structures, which will permit direct osmotic concentration processing of juices and beverages, with or without pulp, and without pretreatment.
The invention is considered to be additionally suitable for the processing of aqueous solution of surface active solutes which are volatile, such as ethyl alcohol, and flavor and fragrance components such as aliphatic and aromatic esters, ethers, ketone, alcohols, and aldehydes. These components, if present in solution in the liquid feed contacting the non- water-wettable membrane, will tend to promote wetting and liquid penetration. On the other hand, if a liquid impermeable but vapor permeable film separates the feed liquid from the membrane, then none of the surface active components will be present as a liquid phase in the membrane, and wetting will not occur. This particular situation is likely to be encountered in osmotic concentration of alcoholic beverages, or of fruit or vegetable extracts rich in flavor/fragrance components. So long as the brine into which these volatiles will condense is sufficiently rich in salt, the brine phase will not be capable of wetting the pores of the membrane, and establishing a liquid pathway for transport.

Claims

1. A membrane structure for use in the osmotic concentration of liquids, said structure including a water-permeable sheet attached to a non-water-wettable, microporous membrane.
2. A membrane structure according to claim 1, wherein said sheet and said membrane form a laminate in which said sheet is laid upon or bonded to said membrane.
3. A membrane structure according to claim 1 or claim 2, wherein said sheet is a thin film.
4. A membrane structure according to claim 3, wherein said thin film is a water- insoluble but water-absorptive (hydrophilic) polymeric membrane such as regenerated cellulose (cellophane).
5. A membrane structure according to claim 3, wherein said thin film is an ultramicroporous, water-wettable ultrafiltration membrane.
6. A membrane structure according to claim 3, wherein said thin film is a thin coating which includes or consists of a water-permeable polymer.
7. A membrane structure according to any preceding claim, wherein said osmotic concentration is of macrosolute-containing, oil-containing or colloid-containing aqueous solutions.
8. A membrane structure according to any preceding claim, wherein said sheet is freely permeable to water, but substantially impermeable to all components or contaminants in the feed liquid which are likely to promote wetting of the microporous membrane.
9. A membrane structure for use in the osmotic concentration of liquids, wherein the feed liquid contains volatile and/or fragrance and/or flavour components, said structure including a liquid impermeable but vapour permeable sheet or film associated with a non- wettable membrane, said sheet separating said feed liquid from said membrane.
10. A method of osmotic concentration, in which a membrane structure, as described in any one of the preceding claims is used.
PCT/AU1992/000396 1991-08-01 1992-07-31 Membrane structure for osmotic concentration WO1993002782A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AUPK7553 1991-08-01
AUPK755391 1991-08-01

Publications (1)

Publication Number Publication Date
WO1993002782A1 true WO1993002782A1 (en) 1993-02-18

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100432273C (en) * 2000-07-14 2008-11-12 3M创新有限公司 Metal matrix composite wires, cables and preparing method

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0394193A2 (en) * 1989-04-14 1990-10-24 Membrane Products Kiryat Weizmann Ltd. Coated membranes
EP0401486A1 (en) * 1989-06-08 1990-12-12 Japan Gore-Tex, Inc. Selectively permeable membrane
EP0456939A1 (en) * 1990-05-18 1991-11-21 Japan Gore-Tex, Inc. Hydrophilic porous fluoropolymer membrane
AU8517491A (en) * 1990-08-30 1992-03-30 E.I. Du Pont De Nemours And Company Gas separation membrane with ultrathin layer

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0394193A2 (en) * 1989-04-14 1990-10-24 Membrane Products Kiryat Weizmann Ltd. Coated membranes
EP0401486A1 (en) * 1989-06-08 1990-12-12 Japan Gore-Tex, Inc. Selectively permeable membrane
EP0456939A1 (en) * 1990-05-18 1991-11-21 Japan Gore-Tex, Inc. Hydrophilic porous fluoropolymer membrane
AU8517491A (en) * 1990-08-30 1992-03-30 E.I. Du Pont De Nemours And Company Gas separation membrane with ultrathin layer

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100432273C (en) * 2000-07-14 2008-11-12 3M创新有限公司 Metal matrix composite wires, cables and preparing method

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