WO2000004985A1 - Membrane poreuse multilumiere et procede de fabrication correspondant - Google Patents

Membrane poreuse multilumiere et procede de fabrication correspondant Download PDF

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Publication number
WO2000004985A1
WO2000004985A1 PCT/US1999/012159 US9912159W WO0004985A1 WO 2000004985 A1 WO2000004985 A1 WO 2000004985A1 US 9912159 W US9912159 W US 9912159W WO 0004985 A1 WO0004985 A1 WO 0004985A1
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WO
WIPO (PCT)
Prior art keywords
membrane
set forth
lumens
lumen
membrane element
Prior art date
Application number
PCT/US1999/012159
Other languages
English (en)
Inventor
John P. Puglia
Original Assignee
Koch Membrane Systems, Inc.
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 Koch Membrane Systems, Inc. filed Critical Koch Membrane Systems, Inc.
Priority to AU42273/99A priority Critical patent/AU4227399A/en
Publication of WO2000004985A1 publication Critical patent/WO2000004985A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
    • B29C43/02—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles
    • B29C43/18—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles incorporating preformed parts or layers, e.g. compression moulding around inserts or for coating articles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
    • B29C43/006—Pressing and sintering powders, granules or fibres
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2031/00—Other particular articles
    • B29L2031/755—Membranes, diaphragms

Definitions

  • the present invention relates in general to filtration devices and, more particularly, to multi-lumen membranes and a method of construction thereof.
  • Membranes are linings or partitions which are able to divide or separate two phases, e.g., a liquid phase from a gas phase, a solid from a liquid, or multiple components of a liquid from each other. These membranes are typically formed from polymers and are semipermeable, allowing a transfer between the phases which are to be separated.
  • the specific physical shape or form of the membranes can vary, and can include flat sheets, tubular membranes, and hollow fibers. The specific use to which the membrane is to be put dictates the form selected for its construction.
  • filtration membranes are used in a variety of applications, including dialysis, gas separation, ultraflltration, macrofiltration, microfiltration, nanofiltration, and reverse osmosis. These membranes use hydraulic pressure to separate the components of a fluid due to differences in the size, shape or physical characteristics of such components. During this filtration, the component which is sized or shaped to pass through the membrane is thereby separated from the rest of the fluid.
  • membranes which are spun can be self- supporting, such as hollow fiber membranes. When the membranes are cast, they are often cast onto porous supports or substrates. The porous substrates are designed so that the fluid component which passes through the membrane can then pass through the porous substrate for collection.
  • polymeric membranes have been constructed from thermoplastic resins. When a thermoplastic resin is used for the membrane, it typically is dissolved in a solvent along with a pore forming additive.
  • some solution- produced membranes are limited in the feed streams which they can process, as the fluid streams processed cannot include solvents that can swell or dissolve the polymers.
  • thermoplastics do not readily form solutions, if at all, thus limiting the polymers which can be used to form the membranes.
  • sintered thermoplastics have been used extensively as . macro porous membranes, as well as microfiltration and ultraflltration membrane supports, in both flat sheet and tubular configurations.
  • Sintered plastics typically comprise thermoplastic polymeric materials which are presented in powdered form, and are then processed into a solid, rigid form with a combination of pressure and heat. All thermoplastic polymers melt, and thus essentially all thermoplastics are suitable for use as sintered plastic membranes, eliminating the problems associated with the solution- driven membrane formation. These products, however, are deficient in that the available contact surface area is relatively small as compared to hollow fiber or small diameter tubular products, which maintain a large membrane area to product volume ratio.
  • inorganic ceramic products have been developed in the industry such as are disclosed in U.S. Patent Nos. 4,069,157, 4,119,503, and 4,251,377.
  • These patents disclose ceramic supports having a multiplicity of parallel passageways or lumens therethrough, wherein the passageways are coated with an ultraflltration membrane. In this manner, the support can achieve a specific area to volume ratio and defined permeability characteristics.
  • These membranes advantageously maintain superior chemical, thermal, and abrasion resistance when compared to conventional polymeric membranes.
  • such supports tend to have unacceptable fragility and pore symmetry, which translate to high pressure drops and a high propensity toward fouling at the separation interface.
  • ceramic supports when positioned in the filtration housing, must have an associated gasket to secure the support within the housing.
  • the associated gaskets cannot, thereby limiting the temperature processing ranges of such ceramic supports due to the temperatures which the gasket can withstand.
  • ceramic supports are limited in their feed stream compatibility, as they cannot effectively process highly hydrophilic materials.
  • the invention is a method for constructing a multi-lumen porous plastic membrane, comprising the steps of providing a thermoplastic resin in powdered form, packing the resin into a mold having a plurality of spaced apart rods extending longitudinally axially through the length thereof to create a plurality of lumens throughout the length of the membrane element to be formed, subjecting the resin to a combination of pressure and. heat until the resin reaches its alpha temperature, and allowing the sintered membrane element to cool.
  • the porosity of the membrane is refined by inserting hollow fiber microfiltration membranes into the lumens of the sintered membrane element.
  • the porosity of the membrane is refined by coating the lumens of the sintered membrane element with a membrane.
  • a membrane coating can also be applied to the outside of the membrane element if desired for specific filtration needs.
  • the invention is related to a multi-lumen porous plastic membrane comprising a sintered porous plastic membrane element having a multiplicity of parallel passageways or lumens therethrough. The passageways may serve as a macro porous filter, or may be coated with a polymeric formulation or alternatively inserted with a porous hollow fiber to refine the porosity of the membrane.
  • Fig. 1 is a fragmentary perspective view of one embodiment the multi- lumen porous plastic membrane element according to the invention.
  • Fig. 2 is an end view of the multi-lumen porous membrane element of the present invention.
  • Fig. 3 is an end view of an alternative embodiment of the multi-lumen porous membrane element of the present invention, depicting hollow fiber membranes positioned within each of the lumens.
  • Fig. 4 is a cross-sectional view of the multi-lumen porous membrane element taken along line 4-4 of Fig. 3, showing a hollow fiber membrane being positioned into one of the lumens thereof.
  • a multi-lumen porous membrane generally referred to by the numeral 10, comprises a porous plastic membrane support element 12.
  • Element 12 is constructed as an integral unit having a multiplicity of parallel passageways or lumens 14 extending longitudinally axially therethrough.
  • Support element 12 can have any suitable shape, including cylindrical, or rectangular, square or polygonal in cross-section. In a preferred embodiment, element 12 is generally hexagonal in cross-section.
  • the passageways or lumens 14 allow support element 12 to function alone as a macro porous filter.
  • the lumens 14 can be coated with a polymeric formulation useful as a membrane, or a hollow fiber membrane can be inserted into the passageways, as will be discussed in more detail below.
  • the membrane support element 12 is constructed from sintered plastic, and can be formed in any suitable manner.
  • the sintered plastic can be selected from any of a number of suitable known thermoplastics, as long as they possess thermoplastic characteristics, i.e., the ability to melt.
  • the membrane support element produced in such a manner is a macro porous element ranging in pore size from about 1 to about 80 microns, with an average porosity of 50%. Varying the particle size of the powdered polymer selected can alter the resultant pore size, as is known to those skilled in the art.
  • These polymers can include, but are not limited to, high density polyethylene, low density polyethylene, very low density polyethylene, ultra high molecular weight polyethylene, polypropylene, polysulfone, polyvinylidene fluoride, polytetrafluoroethylene, ethyl vinyl acetate, polystyrene, polyvinyl alcohol, polyacrylate, nylon, polyethersulfone, and polymethylpentane.
  • the porosity of the resultant membrane support element is controlled by the particle size of the polymer selected, whereby increasing the diameter of the powder results in an increase in the pore size of the resultant element. While some polymers are manufactured in powdered fonn, others must be processed to a powder.
  • the powder is formed by cryogenically grinding the thermoplastic to a certain mesh size.
  • the particle size of the resinous powder is proportional to the porosity and pore size of the resulting macro porous membrane support element.
  • the pore size of the membrane support can be controlled by altering the . temperature and pressure used in the sintering process.
  • the plurality of lumens 14 extending through the membrane support element 12 are preferably spaced equidistant from each other and configured in multiple rows. In the embodiment depicted in the figures, and as preferred, the distance between each lumen 14 is approximately equivalent to the radius of an individual lumen 14.
  • the porosity of the thermoplastic membrane support element 12 can be further refined to create microfiltration (pore sizes of .1 to 5 microns), ultraflltration (pore sizes of .001 to .1 microns), nanofiltration (pore sizes .0001 to .001 microns), and reverse osmosis membranes. Accordingly, when it is desired to have a pore size effective for microfiltration or smaller, for example, the membrane support element 12 is initially constructed to have an average pore size of about 10 microns. As depicted in Fig. 5, the support element 12 can then be treated to alter its mean pore size by coating the interior of the support element 12 with a membrane coating 16.
  • This membrane coating 16 is preferably comprised of a 5 to 50% solution of the polymer from which the support element 12 is constructed in a solvent suitable to bring such polymer into solution. This solution is deposited on the interior of the lumens 14 of the support element 12.
  • the membrane coating can also be deposited on the exterior 18 of the support element 12 (not shown), depending on the desired characteristics of the membrane.
  • the nature of the construction of the support element 12 creates a symmetric filtration device, while use of the membrane coating 16 inside the lumen 14 creates an asymmetric filtration membrane.
  • the membrane coating 16 is also utilized on the exterior 18 of the support element 12, the resultant membrane is symmetric. Alternatively, as shown in Figs.
  • the porosity of the membrane support element 12 can be refined to thereby create an asymmetric membrane by inserting conventional hollow fiber membranes 20 into the lumens 14 of the support element 12.
  • the outer diameter of the hollow fiber membranes 20 approximates the inner diameter of the lumens 14, allowing the hollow fiber membranes 20 to be inserted into the lumens 14 and be retained therein by means of a loose friction fit.
  • the ends of the lumens 14 can be sealed, as with a composite material, to prohibit bypass between the hollow fiber 20 and the lumen 14 of the support element 12.
  • Suitable hollow fiber membranes 20 are those . which have micro, ultra, nano and reverse osmosis membrane properties, as are know to those skilled in the art.
  • a powdered resinous polymer is introduced into an elongated mold (not shown) having a plurality of rods extending longitudinally therethrough.
  • the mold is packed to assure uniform density throughout the mold.
  • End plates are positioned over the ends of the rods at the open end of the mold, and consistent pressure is applied thereto until the plates compact the polymer and stop moving.
  • the mold and thermoplastic resin enclosed therein are placed inside an oven and heated to a temperature ranging from about the alpha temperature of the polymer to less than the melting point of the polymer, with the temperature being uniformly distributed throughout the mold cavity to achieve a uniform product. Once the alpha temperature is achieved, the plates at the ends of the mold will begin to move as the thermoplastic begins to soften, at which point the temperature and pressure are maintained, and fusion of the sintered resin powder particles occurs. Then, the mold and its contents are cooled.
  • the multi-lumen porous membrane 10 is positioned in a housing (not shown) in such a manner that the feed will enter the membrane 10 at one end thereof and be forced to flow through the multiplicity of lumens 14 within the support element 12 by means of hydraulic pressure. This pressure forces the fluid to permeate through the exterior walls 18 of the support 12, to be collected on the outside of the membrane support element 12.
  • the multi-lumen porous membrane 10 of the instant invention can be used to filter a variety of fluids, such as macrofiltration, including prefiltering water to remove particulates larger than 5 to 80 microns; microfiltration, including clarification of fermented beer and removal of metal hydroxides from water; nanofiltration, including removal of organic compounds or sucrose from water; ultraflltration, including removal of bacteria from water; and reverse osmosis, including desalination of water.
  • macrofiltration including prefiltering water to remove particulates larger than 5 to 80 microns
  • microfiltration including clarification of fermented beer and removal of metal hydroxides from water
  • nanofiltration including removal of organic compounds or sucrose from water
  • ultraflltration including removal of bacteria from water
  • reverse osmosis including desalination of water.
  • multi-lumen porous plastic membranes formed in accordance with the present invention possess excellent flux characteristics.
  • the flux exceeds that of conventional hollow fiber membranes.
  • hollow fiber membranes known in the industry are able to withstand transmembrane pressures up to . approximately 50 psi.
  • any ultraflltration processing is limited by this pressure which the hollow fibers can withstand, and multiple cartridges may be required depending upon the amount of feed to be processed in a particular application.
  • the pressure of the feed streams significantly exceeds 50 psi, it may be necessary to collect the feed prior to ultrafiltration, as in a reservoir or the like, reducing to acceptable levels the actual pressure which will be placed on the fibers.
  • the hollow fibers incorporated into the multi-lumen porous membrane of the present invention can withstand transmembrane pressures previously thought impossible.
  • Projected figures below have been provided beyond 110 psi, as the pump utilized in the testing which resulted in these figures was unable to provide higher pressures.
  • the transmembrane pressure of the feed stream processed by a single multi-lumen porous membrane and associated hollow fiber membranes is significantly larger than that which could have been processed utilizing conventional hollow fiber cartridges.
  • a standard hollow fiber cartridge can run at 50 psi and thereby process 800 gfd
  • those same hollow fiber membranes positioned into the membrane support element of the present invention can run at double that pressure, i.e., 100 psi, processing 1876 gfd and increasing the filtration capacity by over 100%>.
  • that same hollow fiber membrane and its associated membrane support element can run as 210 psi, processing 4100 gfd, approximately five times the capacity of standard hollow fiber membranes.
  • a further advantage of this flux increase is that the feed stream pressure which a hollow fiber ultraflltration unit can filter is significantly increased, thereby allowing the cartridge to be used in circumstances for which conventional cartridges were previously unavailable without forcing some alteration of the feed stream pressure by incorporation of reservoirs or the like.
  • a polymer powder comprising 80 micron powder particles of polyvinylidene fluoride was placed into the cavity of a hexagonal cross-sectioned elongated mold having a plurality of evenly spaced rods extending longitudinally therethrough.
  • the mold was periodically vibrated to ensure uniform packing. Consistent pressure was applied to the open end of the mold, and the mold and its contents were placed in an oven. The temperature in the oven caused the contents of the mold to reach . its alpha transition temperature, whereby the polymer became sintered. The mold and sintered plastic were then allowed to cool.
  • Hollow fiber membranes having a 0.2 micron cut-off were then inserted into the lumens.
  • the hollow fibers were secured to the lumens on the ends using a polyurethane potting compound, not only securing the fibers, but also binding the ends so as to prevent bypass by the process stream.
  • the multi-lumen membrane thus formed was then inserted into a stainless steel housing and secured using gaskets and metal couplings.
  • This cartridge was secured to an ultraflltration system and a metal hydroxide solution was run through it, concentrating the hydroxide solution.
  • the concentration of metal hydroxides in the feed stream was as follows: zinc 60.1 mg/1; chromium 7.83 mg/1; and nickel, 172.9 mg/1.
  • the multi-lumen membrane incorporating hollow fibers was subjected to transmembrane pressures ranging from 35/25 psi to 115/105 psi.
  • the rejection of hydroxides was measured at the pressures indicated.
  • measurements were taken of the flux of water prior to processing - l i the feed stream, and subsequent to filtration of the feed stream to measure the degree of . fouling of the membrane.
  • the post filtration flux measurements using a non-fouling fluid indicate that there is only a minimal fouling of the ultraflltration membrane made in accordance with the present invention.
  • the multi-lumen porous membrane of the present invention possesses excellent flux characteristics, allowing hollow fiber membranes to run at transmembrane pressures heretofore unseen with conventional hollow fiber products. Furthermore, increased surface area contact makes the membrane of this invention more efficient than those of the prior art.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)

Abstract

L'invention concerne un procédé de fabrication d'une membrane plastique poreuse multilumière comportant un élément de support membraneux intégré pourvu d'une pluralité de lumières ou voies de passages espacées traversant axialement et longitudinalement ladite membrane. Pour affiner cette dernière, de manière à obtenir des propriétés de membrane différentes, on recouvre d'un revêtement la surface intérieure des lumières et/ou la surface extérieure de l'élément de support membraneux. Dans une variante, on peut obtenir ces propriétés en introduisant des membranes à fibres creuses dans les lumières afin de créer une membrane de microfiltration, de nanofiltration, d'ultrafiltration ou d'osmose inverse.
PCT/US1999/012159 1998-07-22 1999-06-02 Membrane poreuse multilumiere et procede de fabrication correspondant WO2000004985A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU42273/99A AU4227399A (en) 1998-07-22 1999-06-02 Multi-lumen porous membrane and method of construction

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US12082198A 1998-07-22 1998-07-22
US09/120,821 1998-07-22

Publications (1)

Publication Number Publication Date
WO2000004985A1 true WO2000004985A1 (fr) 2000-02-03

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WO (1) WO2000004985A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1328335A1 (fr) * 2000-10-09 2003-07-23 U.S. Filter Wastewater Group, Inc. Systeme de filtration sur membrane ameliore
WO2015044783A3 (fr) * 2013-09-26 2015-06-18 Alto Solution Sa Structure autoportante
WO2016137814A1 (fr) * 2015-02-24 2016-09-01 Porex Corporation Support poreux fritté revêtu d'une membrane pour prélèvement d'échantillons

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3304046A (en) * 1964-04-13 1967-02-14 Harbison Walker Refractories Manufacture of ceramic objects and the like
GB1557899A (en) * 1976-12-09 1979-12-12 Connelly R F Balanced pressure tubular molecular filtration system
CH681281A5 (en) * 1990-04-12 1993-02-26 Johannes Wieser Linhart Dipl I Particle filter for sepg. process materials - comprises particulate porous elongated block with 1st channel for raw mixt. and 2nd channel for permeate
WO1995023639A1 (fr) * 1994-03-02 1995-09-08 Apv Pasilac A/S Ensemble de membranes filtrantes
EP0743085A2 (fr) * 1995-05-16 1996-11-20 Mitsubishi Plastics Inc. Filtre plastique poreux et procédé pour sa production
EP0783914A1 (fr) * 1996-01-12 1997-07-16 Toyoda Boshoku Corporation Elément filtrant pour purificateur d'air

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3304046A (en) * 1964-04-13 1967-02-14 Harbison Walker Refractories Manufacture of ceramic objects and the like
GB1557899A (en) * 1976-12-09 1979-12-12 Connelly R F Balanced pressure tubular molecular filtration system
CH681281A5 (en) * 1990-04-12 1993-02-26 Johannes Wieser Linhart Dipl I Particle filter for sepg. process materials - comprises particulate porous elongated block with 1st channel for raw mixt. and 2nd channel for permeate
WO1995023639A1 (fr) * 1994-03-02 1995-09-08 Apv Pasilac A/S Ensemble de membranes filtrantes
EP0743085A2 (fr) * 1995-05-16 1996-11-20 Mitsubishi Plastics Inc. Filtre plastique poreux et procédé pour sa production
EP0783914A1 (fr) * 1996-01-12 1997-07-16 Toyoda Boshoku Corporation Elément filtrant pour purificateur d'air

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1328335A1 (fr) * 2000-10-09 2003-07-23 U.S. Filter Wastewater Group, Inc. Systeme de filtration sur membrane ameliore
EP1328335A4 (fr) * 2000-10-09 2004-08-25 Us Filter Wastewater Group Inc Systeme de filtration sur membrane ameliore
EP1618946A1 (fr) * 2000-10-09 2006-01-25 US Filter Wastewater Group, Inc. Procédé de filtrage de membranes
WO2015044783A3 (fr) * 2013-09-26 2015-06-18 Alto Solution Sa Structure autoportante
US10130915B2 (en) 2013-09-26 2018-11-20 Alto Solution Sa Self supporting structure for membrane crossflow cartridges
AU2014326293B2 (en) * 2013-09-26 2018-11-29 Alto Solution Sa Self supporting structure for membrane crossflow cartridges
WO2016137814A1 (fr) * 2015-02-24 2016-09-01 Porex Corporation Support poreux fritté revêtu d'une membrane pour prélèvement d'échantillons
US11141951B2 (en) 2015-02-24 2021-10-12 Porex Corporation Membrane-coated sintered porous media for sample collection

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Publication number Publication date
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