WO1996027429A1 - Membrane amelioree - Google Patents

Membrane amelioree Download PDF

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Publication number
WO1996027429A1
WO1996027429A1 PCT/GB1995/002500 GB9502500W WO9627429A1 WO 1996027429 A1 WO1996027429 A1 WO 1996027429A1 GB 9502500 W GB9502500 W GB 9502500W WO 9627429 A1 WO9627429 A1 WO 9627429A1
Authority
WO
WIPO (PCT)
Prior art keywords
membrane
copolymer
propylene oxide
polysulphone
molecular weight
Prior art date
Application number
PCT/GB1995/002500
Other languages
English (en)
Inventor
John Steven Wilkes
Original Assignee
Kalsep Limited
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 Kalsep Limited filed Critical Kalsep Limited
Priority to EP95934726A priority Critical patent/EP0814898A1/fr
Priority to JP8526671A priority patent/JPH11501251A/ja
Priority to AU37039/95A priority patent/AU3703995A/en
Publication of WO1996027429A1 publication Critical patent/WO1996027429A1/fr

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Classifications

    • 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
    • B01D71/66—Polymers having sulfur in the main chain, with or without nitrogen, oxygen or carbon only
    • B01D71/68—Polysulfones; Polyethersulfones
    • 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
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/52—Polyethers
    • B01D71/521—Aliphatic polyethers
    • 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
    • B01D2323/12—Specific ratios of components used
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/30—Cross-linking
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/20—Specific permeability or cut-off range
    • 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

Definitions

  • the present invention relates to a membrane which can be used in filtration and reverse osmosis and which has a reduced tendency to fouling.
  • Membranes are used in phase separation techniques such as filtration, micro- filtration, reverse osmosis etc. and for the recovery of solids.
  • the membranes can be made of polymeric material and a particular class of polymers are the polysulphones, such as polyether sulphones.
  • Polysulphones have been widely used because of their chemical resistance and good physical properties. "Polysulphone” is used as a generic name for a type of high molecular weight polymer containing aromatic nuclei and sulphone groups in the main chain.
  • a typical sulphone is formed as the condensation product of bisphenol 'A' and dichloro-diphenyl-sulphone. Also widely used are polyether sulphones, polyphenyl sulphones and polyarylether sulphones. However polysulphones have a surface which is hydrophobic and, in use polysulphone membranes are subject to fouling, particularly when being used to filter liquids containing organic material such as proteinaceous material. This fouling results in the build up of a layer on the surface of the membrane which blocks the pores of the membrane and causes deterioration in its performance.
  • EP Patent 0407665 Al discloses a blend of a polyether and a polysulphone and a method of making such blends by dissolving both components in n- methylpyrrolidone (NMP), dimethylformamide (DMF) or dimethylacetamide and co-precipitating the polymer blend by a phase inversion process using water.
  • These blends are disclosed as precursor membranes for forming an affinity membrane by reaction of hydroxyl groups on the precursor membrane with biological reactive compounds.
  • the precursor membranes have a pore size with a nominal molecular weight cut off of between 20,000 and 60,000. Nominal molecular weight cut off is a measure of the pore size of very small pore size filters and is measured by ASTM Method Designation El 343-90.
  • These membranes are not suitable for use as filtration membranes in applications other than in applications below 100 Angstroms (the so called reverse osmosis and nano-filtration range) this is because of the small pore size of the membranes.
  • these membranes do not have permanent hydrophilicity and the polyether copolymer continued to be leached from the membranes.
  • the precursor membrane blends are not dried but are reacted with the biologically active compound in the wet condition. Drying of these blends would cause a collapse of the membrane structure and this limits their use.
  • a membrane which comprises a blend of a polysulphone and an ethylene oxide/propylene oxide copolymer which has a pore size with a molecular weight cut off of greater than 60,000.
  • the membranes of the present invention have a pore size with a molecular weight cut off of greater than 250,000 and up to 1 micron (l ⁇ ).
  • the polysulphone can be any polysulphone which can be produced in the form of a film, membrane, hollow fibre or other configuration which is conventionally used and preferred polysulphones are polyether sulphones.
  • Polysulphones are described in US Patent 4,230,463. Polysulphones having aromatic hydrocarbyl-containing moieties generally have good thermal stability . Polysulphones and polyether sulphones are sold under the trade names UDEL, P-1700 and P-3500 by Union Carbide, ASTREL 360 Plastic by the 3M Company by ICI pic, and as Ultrasons such as Polysulphone Ultrason S and Polysulphone Ultrason E.
  • the molar ratio of polysulphone to ethylene oxide/propylene oxide copolymer is preferably from 1 : 10 to 2: 1 and more preferably from 1 : 5 to 1:1.
  • the membranes of the present invention preferably have a structure such that the ethylene oxide/propylene oxide copolymer molecules are concentrated towards the surface of the membrane, so that the more hydrophilic copolymer molecules cause the surface of the material to be rendered more hydrophilic with little or no loss in the performance of the membrane.
  • One part of the ethylene oxide/propylene oxide copolymer molecule is substantially miscible with the polysulphone polymer and one part (the more hydrophilic part) can be less miscible.
  • the properties of the final composition can be varied.
  • the ethylene oxide/propylene oxide copolymer preferably has a ratio of ethylene oxide to propylene oxide groups such that the copolymer is substantially water soluble whilst being compatible with the polysulphone in solvent solution.
  • Suitable copolymers which can be used preferably have a weight average molecular weight of 2,000 to 20,000.
  • the molar ratio of ethylene oxide to propylene oxide groups in the ethylene oxide/propylene oxide copolymer is preferably from 1 : 10 to 9: 10.
  • the blends can be prepared by dissolving both polymer components in a solvent and co-precipitating the blend by a phase inversion process.
  • the solvent for the polymers should be one which is inert to the polymers and will dissolve both polymers for example n-methlpyrolidone, dimethylformamide, dimethylacetamide and similar compounds.
  • pore modifying agents which can be used are non-solvents such as water, alcohols such as n-butanol, polyethylene glycols (PEG), glycerols, polyvinylpyrrolidones (PNP).
  • PEG polyethylene glycols
  • PNP polyvinylpyrrolidones
  • the polyethylene glycols which have been found particularly useful in forming polymer blends of the appropriate pore size are those of molecular weight of 200,000 - 800,000.
  • the polyethylene glycol is preferably present in an amount up to 80% of the liquid, the PVP up to 50%, the butanol up to 20%, the glycerols up to 20% and the water up to 15%
  • the process which is used to precipitate the polymer blend from the solution is precipitation by the phase inversion process from the solution of the components (polyblend solution) using a precipitation liquid.
  • the ethylene oxide/propylene oxide copolymer is enriched at the surface of the membrane linking in the phase inversion process, because of the migration of the water soluble component to the colloidal interface.
  • the ethylene oxide/propylene oxide copolymer and polysulphone are co-precipitated from the solvent and, because of the more hydrophilic nature of the ethylene oxide/propylene oxide copolymer, the copolymer migrates to the solvent/precipitation liquid interface thus enriching the surface of the membrane formed. It is thought that the ethylene oxide/propylene oxide copolymer molecules align themselves with their hydrophilic component aligned towards the precipitation liquid and the non-hydrophilic part aligned towards the hydrophobic polysulphone polymer matrix enriching the surface of the membrane to make it more hydrophilic.
  • the incorporation of the ethylene oxide/propylene oxide copolymer within the polysulphone polymer matrix is indicated by the fact that the ethylene oxide/propylene oxide copolymer cannot be removed by repeated washing and also gives a permanent change of physical characteristics such as strength and pore size.
  • EP04076651A1 water is disclosed as the precipitation liquid, but we have surprisingly found that, if pore enlarging agents are added to the precipitation liquid membranes are produced with a larger pore size.
  • the pore enlarging agents which can be used are low molecular weight alcohols such as methanol, ethanol, polyethylene glycols, glycerols, solvents such as NMP, DMF, dimethyl acetamide and the like.
  • the polyethylene glycols which have been found particularly useful in forming polymer blends of the appropriate pore size are those of molecular weight of 200,000 - 800,000.
  • the amount of these pore enlarging agents present in the precipitation liquid can be up to 100% (i.e.
  • the ethylene oxide/propylene oxide copolymer can be made by conventional methods.
  • the copolymer may be cross-linked.
  • cross-linking can be carried out using an appropriate cross-linking agent.
  • Cross-linking agents which can be used are isocyanates, dicarboxlic acid halides, chlorinated epoxides such as epichlorohydrin, cross-linking can also be achieved by UN radiation, for example by use of iso-butronitrile and subsequent reaction with a suitable divalent species.
  • the degree of cross-linking can be controlled by the type and concentration of the cross-linking agent, the duration of the treatment and the temperature. The more severe the cross-linking treatment, the higher the molecular weight of the final cross-linked product.
  • the membrane is preferably washed to remove excess unreacted ethylene oxide/propylene oxide copolymer. The cross linking virtually eliminated leaching of the copolymer.
  • the membranes of the invention can be of conventional type e.g. in the form of sheets, tubes, hollow fibres etc.
  • hydrophilicity of a polysulphone membrane can be permanently increased with little or no deleterious effect on its performance in filtration. This increase hydrophilicity will reduce the tendency of the membrane to foul.
  • a further feature of the membranes of the invention is that they have advantages when they are used in microfiltration or ultrafiltration.
  • microfiltration and ultrafiltration it is important that the membranes are wetted before use i.e. the pores which are filled with air become filled with liquid.
  • polysulphones this is not possible as they have a low hydrophilicity and in use can involve difficult pre-wetting of the polysulphone membrane with a liquid with a low surface tension e.g. alcohol and trying to ensure that the membrane is completely pre- wetted before it can be used in aqueous filtration.
  • the membranes of the present invention because of the more hydrophilic nature of the membrane, can be wetted with water and so can be used in microfiltration and, in particular microfiltration membranes are wetted instantaneously on contact with water, and after repeated drying.
  • micro-filtration membranes are supplied dry and wetted for use, and it is a feature of the invention that it can produce micro-filtration membranes which can be dried and subjected to repeated drying without collapse of the structure, which happens with membranes produced by the prior art methods.
  • micro-filtration membranes of the present invention generally have a pore size of 0. l ⁇ to 1 micron and are hydrophilic.
  • the membranes of the present invention can be dried without loss of membrane structure.
  • the process of the present invention can also produce membranes with a "tortuous" structure, this means that the membranes have a sponge like structure rather than a macrovoidal structure and enables greater filtration capacity to be obtained.
  • a tortuous structure there is an interconnecting of polymer strands which form a reticulated open cell matrix and so the membranes have a high void space.
  • contaminants can penetrate into the membrane matrix.
  • the dirt holding capacity of the membrane which is associated with assymetry and void space, is the principle determining factor affecting its performance.
  • the tortuous structure is therefore preferred and the interconnecting of the of the matrix gives enhanced mechanical strength to the membrane (burst strength) compared with the macrovoidal structure.
  • Example 1 is an example of a membrane prepared by the process of EP 0407 665A1
  • Example 1 is an example of a membrane prepared by the process of EP 0407 665A1
  • a polyether sulphone sold under the Trade Name Ultrason E and an ethylene oxide/propylene oxide copolymer of molecular weight 9800 (Pluronic F82) were dissolved in n-methylpyrolidone (NMP) and stirred until a clear solution was obtained.
  • NMP n-methylpyrolidone
  • the solution was cast into a membrane by the phase inversion process by casting the solution on to a plate using water as the precipitant liquid.
  • the weight composition of the solution was 30% polyether sulphone(PES), 10% ethylene oxide/propylene oxide copolymer and 60% n-methylpyrolidone.
  • the membranes formed were left to soak in water for one hour after formation. This membrane was tested and it had a molecular weight cut off of 18,000.
  • the membrane was dried by blowing air over it and the structure collapsed and was unable to be used as a membrane.
  • the structure of the membrane was examined under a microscope at a magnification of 300 and it was found to have a macrovoidal structure. Repeated washing with pure water at 20°C led to leaching of copolymer from the surface.
  • Example 1 The process of Example 1 was repeated with various pore modifying agents added to the solution of polysulphone and copolymer in NMP and using different precipitant liquid compositions. The results shown in Table 1
  • the pore size in the Examples 1 to 7 was measured as the molecular weight cut off and measured by ASTM method El 343-90.
  • the pore size in Examples to 11 is the average pore size measured in microns.
  • the temperature measured is the temperature of the quenching liquid.
  • Example 7 The membranes of Examples 7 - 1 1 were dried by blowing air over them and the membrane structure remained intact enabling them to be handled in the dried state. Repeated washing with pure water at 20 °C did not leach any copolymer from the membrane surface.
  • Example 13 The membranes of Examples 7 - 1 1 were dried by blowing air over them and the membrane structure remained intact enabling them to be handled in the dried state. Repeated washing with pure water at 20 °C did not leach any copolymer from the membrane surface.
  • Epichlorohydrin was solubiUsed in an aqueous n-methylpyrolidone blend comprising by weight 75% n-methylpyrolidone, 25% water.
  • the solution was rendered alkaline by the addition of sodium hydroxide until a pH of 13 was achieved.
  • This solution had a composition by weight of 5% epichlorohydrin, 70% n-methylpyrolidone and 25% water.
  • a membrane prepared as in Example 3 with a molecular weight cut off of 150,000 was contacted with the cross-linking agent of (b) for 12 hrs. at a temperature of 20°C.
  • the membrane was washed with water and it could be shown that cross-linking had taken place by the increase in density and reduction in flexibility of the membrane and the fact that no more ethylene oxide/propylene oxide copolymer could be removed with repeated washing.
  • the cross-linked copolymer formed as in Example 1 was compared with the uncross-linked membrane for various fluxes of clean water at varying pressures and the results shown in the accompanying drawing.
  • the cross-linked copolymer was compared with the uncross-linked membrane for various fluxes of clean water at varying pressures and the results shown in accompanying drawing in which the flux of water in litres per square metre per hour is plotted against the time in minutes. As can be seen the cross-linking produces a membrane with an improved flux.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Dispersion Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)
  • Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)

Abstract

Une membrane, avec une surface hydrophile formée à partir d'un mélange polymère de polysulfone et de copolymère d'oxyde d'éthylène et d'oxyde de propylène avec une limite inférieure du poids moléculaire de plus 20000, peut être formée par addition d'agents modifiant la porosité au mélange de polymères et/ou d'agents capables d'élargir les pores au liquide de précipitation utilisé, lors de la formation de la membrane à partir d'une solution des polymères.
PCT/GB1995/002500 1995-03-03 1995-10-23 Membrane amelioree WO1996027429A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
EP95934726A EP0814898A1 (fr) 1995-03-03 1995-10-23 Membrane amelioree
JP8526671A JPH11501251A (ja) 1995-03-03 1995-10-23 改良膜
AU37039/95A AU3703995A (en) 1995-03-03 1995-10-23 Improved membrane

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9504251.1 1995-03-03
GBGB9504251.1A GB9504251D0 (en) 1995-03-03 1995-03-03 Improved membrane

Publications (1)

Publication Number Publication Date
WO1996027429A1 true WO1996027429A1 (fr) 1996-09-12

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ID=10770556

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1995/002500 WO1996027429A1 (fr) 1995-03-03 1995-10-23 Membrane amelioree

Country Status (7)

Country Link
EP (1) EP0814898A1 (fr)
JP (1) JPH11501251A (fr)
CN (1) CN1177308A (fr)
AU (1) AU3703995A (fr)
CA (1) CA2212526A1 (fr)
GB (1) GB9504251D0 (fr)
WO (1) WO1996027429A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999055449A1 (fr) * 1998-04-23 1999-11-04 Kalsep Limited Membrane faite d'un melange de polysulfone ou de polyether sulfone et d'une ethylenediamine a substitution oxyde de polyethylene, oxyde de polypropylene
US20130313182A1 (en) * 2012-05-24 2013-11-28 Iucf-Hyu (Industry-University Cooperation Foundation Hanyang University) Separation membrane and water treatment device including the same
WO2017045983A1 (fr) * 2015-09-17 2017-03-23 Basf Se Procédé de fabrication de membranes

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR102002367B1 (ko) * 2016-10-20 2019-07-23 주식회사 엘지화학 역삼투막 보호층 형성용 조성물, 이를 이용한 역삼투막 제조방법, 역삼투막 및 수처리 모듈
CN106674580B (zh) * 2017-01-04 2019-04-16 南京工业大学 一种聚砜类纳米多孔聚合物的制备方法
EP3756754A1 (fr) * 2019-06-27 2020-12-30 3M Innovative Properties Company Additifs réactifs dans la préparation de membranes

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4046843A (en) * 1974-09-05 1977-09-06 Sumitomo Chemical Company, Limited Process for preparing membranes for separation of substances
EP0037181A1 (fr) * 1980-03-25 1981-10-07 Imperial Chemical Industries Plc Compositions à base d'un mélange de polymères compatibles en forme de films contentant des oxides de polyalkylène et des sulfones de polyéther aromatique
DE4000825A1 (de) * 1990-01-13 1990-05-03 Horst Dipl Chem Dr Perl Hydrophile membranfilter aus polysulfon fuer mikrofiltration und verfahren zur herstellung dieser filter
EP0407665A1 (fr) * 1988-01-14 1991-01-16 The Standard Oil Company Membranes d'affinité portant des groupes terminaux et leurs procédé de préparation et d'application

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4906375A (en) 1984-07-14 1990-03-06 Fresenius, Ag Asymmetrical microporous hollow fiber for hemodialysis

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4046843A (en) * 1974-09-05 1977-09-06 Sumitomo Chemical Company, Limited Process for preparing membranes for separation of substances
EP0037181A1 (fr) * 1980-03-25 1981-10-07 Imperial Chemical Industries Plc Compositions à base d'un mélange de polymères compatibles en forme de films contentant des oxides de polyalkylène et des sulfones de polyéther aromatique
EP0407665A1 (fr) * 1988-01-14 1991-01-16 The Standard Oil Company Membranes d'affinité portant des groupes terminaux et leurs procédé de préparation et d'application
DE4000825A1 (de) * 1990-01-13 1990-05-03 Horst Dipl Chem Dr Perl Hydrophile membranfilter aus polysulfon fuer mikrofiltration und verfahren zur herstellung dieser filter

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP0814898A1 *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999055449A1 (fr) * 1998-04-23 1999-11-04 Kalsep Limited Membrane faite d'un melange de polysulfone ou de polyether sulfone et d'une ethylenediamine a substitution oxyde de polyethylene, oxyde de polypropylene
US6495043B1 (en) 1998-04-23 2002-12-17 Kalsep Limited Membrane which comprises a blend of a polysulphone or a polyether sulphone and polyethylene oxide/polypropylene oxide substituted ethylene diamine
US20130313182A1 (en) * 2012-05-24 2013-11-28 Iucf-Hyu (Industry-University Cooperation Foundation Hanyang University) Separation membrane and water treatment device including the same
US9540255B2 (en) * 2012-05-24 2017-01-10 Samsung Electronics Co., Ltd. Separation membrane and water treatment device including the same
WO2017045983A1 (fr) * 2015-09-17 2017-03-23 Basf Se Procédé de fabrication de membranes

Also Published As

Publication number Publication date
JPH11501251A (ja) 1999-02-02
MX9706645A (es) 1998-06-28
GB9504251D0 (en) 1995-04-19
CA2212526A1 (fr) 1996-09-12
EP0814898A1 (fr) 1998-01-07
CN1177308A (zh) 1998-03-25
AU3703995A (en) 1996-09-23

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