WO1990011120A1 - Ultrafiltration membrane - Google Patents

Ultrafiltration membrane Download PDF

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Publication number
WO1990011120A1
WO1990011120A1 PCT/CA1990/000090 CA9000090W WO9011120A1 WO 1990011120 A1 WO1990011120 A1 WO 1990011120A1 CA 9000090 W CA9000090 W CA 9000090W WO 9011120 A1 WO9011120 A1 WO 9011120A1
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WO
WIPO (PCT)
Prior art keywords
membrane
extrafiltrator
solution
water
amount
Prior art date
Application number
PCT/CA1990/000090
Other languages
French (fr)
Inventor
Ying Wang
Qilian Yang
Original Assignee
International Applied Sciences, 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 International Applied Sciences, Inc. filed Critical International Applied Sciences, Inc.
Priority to AU53354/90A priority Critical patent/AU5335490A/en
Publication of WO1990011120A1 publication Critical patent/WO1990011120A1/en

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D69/00Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/10Supported membranes; Membrane supports
    • B01D69/106Membranes in the pores of a support, e.g. polymerized in the pores or voids
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D69/00Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/14Dynamic membranes
    • B01D69/141Heterogeneous membranes, e.g. containing dispersed material; Mixed matrix membranes
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D65/00Accessories or auxiliary operations, in general, for separation processes or apparatus using semi-permeable membranes
    • B01D65/02Membrane cleaning or sterilisation ; Membrane regeneration
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D69/00Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/14Dynamic membranes
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D71/00Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06Organic material
    • B01D71/52Polyethers
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2321/00Details relating to membrane cleaning, regeneration, sterilization or to the prevention of fouling
    • B01D2321/02Forward flushing

Definitions

  • This invention relates to the field of filtration membranes for use in purification of water.
  • ⁇ purifier for use in such systems.
  • One such purifier is a fibre filter.
  • Another such purifier is more comprehensive and includes an activated charcoal filter, a germicidal system which may use ultraviolet light and a hollow fibre extrafiltrator. Either of these purification systems are connected to a building's water system and the purified water is typically consumed after it has either been heated or cooled.
  • the present invention provides an ultrafiltration membrane formed on an extrafiltrator for use in a water purification system, said ultrafiltration membrane comprising: a membrane material selected from the group of resins consisting of furan, furfural, furfurone, furfuronal and furfuryl alcohol; said membrane having a thickness of from 50 microns to 40,000 microns; said membrane having pores with a diameter of from 5 ⁇ A to lOOA; and, said membrane having been formed dynamically within the pores of said extrafiltrator.
  • a method for forming an ultrafiltration membrane on an extrafiltrator comprising the steps of: preparing a membrane forming solution by dissolving a membrane forming material in a solvent and adding to the solution so obtained, a diluent, a plasticizer, a curing agent and a pore forming agent; and, passing said membrane forming solution through said extrafiltrator to cause a membrane to deposit within the pores of said extrafiltrator, and permitting the membrane so deposited to crosslink and fixate in said pores.
  • a method for filtering water using an ultrafiltration membrane deposited on an extrafiltrator including the steps of: passing water through an extrafiltrator having an ultrafiltration membrane deposited thereon; and periodically stopping the flow of water into said extrafiltrator and allowing unfiltered water to drain from said extrafiltrator.
  • Fig. 1 is a schematic diagram showing a process for membrane formation according to the present invention.
  • Fig. 2 is a schematic diagram showing a water purification system using a membrane filter according to the present invention.
  • a polymer material is used to form a membrane layer within the pores of the extrafiltrator of commercially available drinking water purification systems.
  • the extrafiltrators may be any of the types comprising hollow fibres, spirally wound modules, or flat filters made from polypropylene, nylon, cellulose or aromatic amides having a pore diameter of from 0.02A to I.OA and being of a thickness from about 8 to 200 microns.
  • the ultrafiltration membrane is an extra thick film which is able not only to remove low molecular weight organic substances that cannot be removed by the commercial extrafiltrator, but also the nitrous salts, metal salts, radioactive substances and suspended bacteria. Due to the thickness of the film, water can pass through with relatively small resistance thereby giving a relative high productivity per unit.
  • a membrane forming material 1 is dissolved in a solvent 2, and a diluent 3, plasticizer 4, curing agent 5 and pore forming agent 6 are added to the solution 8.
  • a commercial extrafiltrator 9 is connected by a pump 7 to the solution 8.
  • the solution 8 is passed through the pores of the extrafiltrator and causes deposition of membrane forming material in the pores of the extrafiltrator.
  • the membrane forming material condenses in the pores and is cross linked and fixated " therein. This results in an ultrafiltration membrane having a pore size significantly less than the original pore size of the extrafiltrator.
  • the amount of polymerization of the pore forming agent and, accordingly, the size of the pore forming agent is controlled by controlling the pH of the membrane forming solution.
  • Sodium hydroxide may be added at the outset to increase the pH of the solution which tends to suppress the molecular weight of the pore forming material.
  • the pH of the solution is gradually reduced by the addition of sulphuric acid. This causes an increase in the amount of polymerization and, accordingly, an increase in the molecular weight of the pore forming material.
  • the pore forming material will have the optimum molecular weight to deposit in the pores of the extrafiltrator to give a membrane of the desired separation qualities.
  • an indicator such as phenolphthalein or xylenoblue may be added to the solution.
  • the indicator concentration in the solution passing through the membrane may then be monitored, for example, using photometric means. Once the indicator concentration shows that the membrane has achieved the desired amount of separability, the passing of solution through the extrafiltrator is stopped.
  • the membranes may be stored in a disinfectant and preservative solution.
  • a suitable solution contains 1% ethyl alcohol, 5% glycerol and 1% formalin in water.
  • Ultrafiltration membranes may be produced as described above using an extrafiltrator having the following properties as a substrate:
  • Suitable membrane forming materials include furan resins such as furfural resin, furfuran resin, furfuronal resin, and furfuryl alcohol resin in concentrations of from 1 to 200 mg/1.
  • Suitable diluents include lower alcohols and ketones such as Cl to C5 alcohols, in an amount of from 1 to 99% per volume of the membrane forming liquid.
  • a suitable plasticizer is phthalic phosphoric ester in a concentration of from 0.5-500 mg/1.
  • Suitable curing agents include benzene sulfonylchloride, ethyl sulfate and sulphuric acid in a concentration of from 0.9-5% by volume of the membrane forming solution.
  • the pore forming agent may be a neutral soluble inorganic salt in a concentration of from 20-1500 mg/1 and a surfactant in a concentration of from 20-1500 mg/1.
  • Suitable surfactants include alkyl sodium sulphate, quaternary ammonium salts and polyoxyethylene.
  • a water purification system incorporating an ultrafiltration membrane as described above is illustrated in Figure 2.
  • the system consists of a dynamically formed membrane module 10, three three-way electromagnetic valves 11, 12 and 13, a two-way electromagnetic valve 15 controlled by relay 14 for controlling water level, a relay or micro-computer 16 for controlling time, a water tank 17 and hot and cold water valves 18 and 19 respectively.
  • relay 14 opens the two way electromagnetic valve 15 to permit tap water to pass therethrough.
  • the tap water flows through the three-way electromagnetic valve 11 and into the membrane module 10.
  • Purified water passing from the membrane module . 10 flows into the two three-way electromagnetic valves 12 and 13.
  • Valve 13 is controlled by either a time relay or micro-computer indicated by reference 16.
  • valve 13 For the first two to five minutes, the valve 13 is positioned so as to discharge water through a waste outlet 22 in order to flush the system. Once the system flushing time has expired, valve 13 is positioned so as to stop discharge through the waste outlet 22 and to cause purified water to drain into the tank 17 from the clean water outlet 23.
  • Cool water is provided at outlet 18 through the use of water cooler 20.
  • Hot water is provided at outlet 19 by means of water heater 21.
  • the relay 14 for controlling water level will close the two-way electromagnetic valve 15 thereby shutting off water entry into the system from the water source.
  • the three-way electromagnetic valves 11, 12 and 13 may periodically be activated so as to cause waste water from the membrane module 10 to be drained through the waste water outlet 22.
  • Such periodic draining of the membrane module removes a portion of the contaminants from the non-filtered side of the module thereby reducing blockage and deposition of waste substances in the membrane module, increasing the life span of the module and optimizing both the flow rate through the module and the purified water quality.
  • Example 1 The present invention may be further illustrated by reference to the following examples: Example 1
  • the membrane forming solution 50 ppm furfurol alcohol was added to water. To this solution was added 1% ethyl alcohol, 0.1% polyoxyethylene. Sodium hydroxide was then added to this solution to adjust the pH to 8 and xylenoblue was added as an indicator. The pump was activated and operated at a pressure of 3 kg/cm 2 . After approximately 2-3 minutes, small amounts of sulphuric acid were added to lower the pH and the indicator concentration was measured with a photometer. After approximately 30 minutes, the solution had a pH of approximately 3 and the concentration of indicator in the permeate water as compared with the concentration of indicator remaining in the feedwater was approximately 95%.
  • the extrafiltrator in this example contained a polypropylene hollow fibre module having a membrane thickness of 50 microns and a pore size of .6 microns.
  • the membrane solution contained 50 ppm furol, .7% dibutic phthalate, water, acetone, ethyl sulphate, sodium dodecyl sulfonate and phenolphthalein.
  • the solution was made by dissolving furol in acetone, dibutic phthalate and ethyl sulphate to form a first solution.
  • This first solution was poured into water to achieve the above concentration and sodium dodecyl sulfonate was dissolved in the solution while adding phenolphthalein.
  • the pump was turned on and operated at a pressure of approximately 3 kg/cm 2 . The pump was operated for approximately 60 minutes and the concentration of indicator measured using a photometer.
  • the indicator concentration in the permeate was approximately 95% of that in the feedwater.
  • the pump was stopped and the membrane was treated with a preserving solution containing 1% ethyl alcohol, 5% glycerol and 1% formalin in water.

Abstract

An ultrafiltration membrane is formed on an extrafiltrator for use in a water purification system. The ultrafiltration membrane has a membrane material which may be furan, furfural, furfona, furfonal and furfuryl alcohol. The membrane has a thickness of from 50 microns to 40,000 microns and contains pores having a diameter of from 50 Å to 100 Å. A method for forming such a membrane dynamically within the pores of an extrafiltrator is also provided. The method includes the preparation of a membrane forming solution containing a membrane forming material, a solvent, a diluent, a plasticizer, a curing agent and a pore forming agent and passing the membrane forming solution through the extrafiltrator to cause a membrane to deposit within the pores of the extrafiltrator, to crosslink and fixate in the pores. A method for filtering water using such an ultrafiltration membrane is provided. The method includes the steps of passing water through an extrafiltrator having such an ultrafiltration membrane deposited thereon and periodically stopping the flow of water into the extrafiltrator to allow unfiltered water to drain from the extrafiltrator.

Description

Title: Ultrafiltration Membrane
FIELD OF THE INVENTION
This invention relates to the field of filtration membranes for use in purification of water.
BACKGROUND OF THE INVENTION
Commercial drinking water systems, such as those used in offices, generally consist of a water purifier and either a cooler or heater. There are two common types of purifier for use in such systems. One such purifier is a fibre filter. Another such purifier is more comprehensive and includes an activated charcoal filter, a germicidal system which may use ultraviolet light and a hollow fibre extrafiltrator. Either of these purification systems are connected to a building's water system and the purified water is typically consumed after it has either been heated or cooled.
The benefits of the previous systems include the removal of pigment, suspended matter and free chlorine. These systems however have some shortcomings. Firstly, eventually the ability of the activated charcoal to adsorb the organic substances will be diminished, necessitating replacement of the activated charcoal filter after adsorption saturation. Prior to replacement, however, harmful nitrous salts and more bacteria may be formed by long-term interaction between the activated charcoal in the filter and bacteria in contact therewith.
Another disadvantage with these prior systems is that the hollow fibre extrafiltrators presently commercially available are not able to remove the low molecular weight organic substances in the tap water completely. These may include potentially carcinogenic substances such as trichloromethane, tetrochloromethane and non polar organic materials. SUMMARY OF THE INVENTION
The present invention provides an ultrafiltration membrane formed on an extrafiltrator for use in a water purification system, said ultrafiltration membrane comprising: a membrane material selected from the group of resins consisting of furan, furfural, furfurone, furfuronal and furfuryl alcohol; said membrane having a thickness of from 50 microns to 40,000 microns; said membrane having pores with a diameter of from 5θA to lOOA; and, said membrane having been formed dynamically within the pores of said extrafiltrator. A method is also provided for forming an ultrafiltration membrane on an extrafiltrator, said method comprising the steps of: preparing a membrane forming solution by dissolving a membrane forming material in a solvent and adding to the solution so obtained, a diluent, a plasticizer, a curing agent and a pore forming agent; and, passing said membrane forming solution through said extrafiltrator to cause a membrane to deposit within the pores of said extrafiltrator, and permitting the membrane so deposited to crosslink and fixate in said pores.
A method is provided for filtering water using an ultrafiltration membrane deposited on an extrafiltrator, said method including the steps of: passing water through an extrafiltrator having an ultrafiltration membrane deposited thereon; and periodically stopping the flow of water into said extrafiltrator and allowing unfiltered water to drain from said extrafiltrator.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described below with reference to the appended drawings which form a part of the specification and in which:
Fig. 1 is a schematic diagram showing a process for membrane formation according to the present invention; and.
Fig. 2 is a schematic diagram showing a water purification system using a membrane filter according to the present invention.
BRIEF DESCRIPTION OF PREFERRED EMBODIMENTS According to the present invention, a polymer material is used to form a membrane layer within the pores of the extrafiltrator of commercially available drinking water purification systems. The extrafiltrators may be any of the types comprising hollow fibres, spirally wound modules, or flat filters made from polypropylene, nylon, cellulose or aromatic amides having a pore diameter of from 0.02A to I.OA and being of a thickness from about 8 to 200 microns. The ultrafiltration membrane is an extra thick film which is able not only to remove low molecular weight organic substances that cannot be removed by the commercial extrafiltrator, but also the nitrous salts, metal salts, radioactive substances and suspended bacteria. Due to the thickness of the film, water can pass through with relatively small resistance thereby giving a relative high productivity per unit.
Referring to Figure 1, the process of dynamic membrane formation is illustrated. A membrane forming material 1 is dissolved in a solvent 2, and a diluent 3, plasticizer 4, curing agent 5 and pore forming agent 6 are added to the solution 8.
Generally, >a commercial extrafiltrator 9 is connected by a pump 7 to the solution 8. When the pump is activated, the solution 8 is passed through the pores of the extrafiltrator and causes deposition of membrane forming material in the pores of the extrafiltrator. The membrane forming material condenses in the pores and is cross linked and fixated" therein. This results in an ultrafiltration membrane having a pore size significantly less than the original pore size of the extrafiltrator.
The amount of polymerization of the pore forming agent and, accordingly, the size of the pore forming agent, is controlled by controlling the pH of the membrane forming solution. Sodium hydroxide may be added at the outset to increase the pH of the solution which tends to suppress the molecular weight of the pore forming material. As the solution is passed through the extrafiltrator, the pH of the solution is gradually reduced by the addition of sulphuric acid. This causes an increase in the amount of polymerization and, accordingly, an increase in the molecular weight of the pore forming material. Eventually, the pore forming material will have the optimum molecular weight to deposit in the pores of the extrafiltrator to give a membrane of the desired separation qualities.
In order to monitor the separation ability of the membrane, an indicator such as phenolphthalein or xylenoblue may be added to the solution. The indicator concentration in the solution passing through the membrane may then be monitored, for example, using photometric means. Once the indicator concentration shows that the membrane has achieved the desired amount of separability, the passing of solution through the extrafiltrator is stopped.
After membrane formation has been completed, the membranes may be stored in a disinfectant and preservative solution. A suitable solution contains 1% ethyl alcohol, 5% glycerol and 1% formalin in water.
Ultrafiltration membranes may be produced as described above using an extrafiltrator having the following properties as a substrate:
thickness of substrate 8 - 200 microns; pore diameter of substrate 0.02-1 microns; material of substrate polypropylene, nylon, cellulose, aromatic amide; and shape of substrate hollow fibre, spiral- wound module and flat. Such membranes typically have a thickness of from 50 microns to 40,000 microns and a pore size of from 5θA to lOOA. Suitable membrane forming materials include furan resins such as furfural resin, furfuran resin, furfuronal resin, and furfuryl alcohol resin in concentrations of from 1 to 200 mg/1.
Suitable diluents include lower alcohols and ketones such as Cl to C5 alcohols, in an amount of from 1 to 99% per volume of the membrane forming liquid.
A suitable plasticizer is phthalic phosphoric ester in a concentration of from 0.5-500 mg/1.
Suitable curing agents include benzene sulfonylchloride, ethyl sulfate and sulphuric acid in a concentration of from 0.9-5% by volume of the membrane forming solution.
Water is typically used as the solvent and forms from 1 to 99% by volume of the membrane forming solution. The pore forming agent may be a neutral soluble inorganic salt in a concentration of from 20-1500 mg/1 and a surfactant in a concentration of from 20-1500 mg/1. Suitable surfactants include alkyl sodium sulphate, quaternary ammonium salts and polyoxyethylene.
A water purification system incorporating an ultrafiltration membrane as described above is illustrated in Figure 2. The system consists of a dynamically formed membrane module 10, three three-way electromagnetic valves 11, 12 and 13, a two-way electromagnetic valve 15 controlled by relay 14 for controlling water level, a relay or micro-computer 16 for controlling time, a water tank 17 and hot and cold water valves 18 and 19 respectively. In use, when the tank 17 is empty, relay 14 opens the two way electromagnetic valve 15 to permit tap water to pass therethrough. The tap water flows through the three-way electromagnetic valve 11 and into the membrane module 10. Purified water passing from the membrane module . 10 flows into the two three-way electromagnetic valves 12 and 13. Valve 13 is controlled by either a time relay or micro-computer indicated by reference 16. For the first two to five minutes, the valve 13 is positioned so as to discharge water through a waste outlet 22 in order to flush the system. Once the system flushing time has expired, valve 13 is positioned so as to stop discharge through the waste outlet 22 and to cause purified water to drain into the tank 17 from the clean water outlet 23.
Cool water is provided at outlet 18 through the use of water cooler 20.
Hot water is provided at outlet 19 by means of water heater 21. When the water tank 17 is filled with purified water, the relay 14 for controlling water level will close the two-way electromagnetic valve 15 thereby shutting off water entry into the system from the water source.
The three-way electromagnetic valves 11, 12 and 13 may periodically be activated so as to cause waste water from the membrane module 10 to be drained through the waste water outlet 22. Such periodic draining of the membrane module removes a portion of the contaminants from the non-filtered side of the module thereby reducing blockage and deposition of waste substances in the membrane module, increasing the life span of the module and optimizing both the flow rate through the module and the purified water quality.
The present invention may be further illustrated by reference to the following examples: Example 1
An extrafiltrator made of the cellulose hollow fibres manufactured in U.S.A. by Microgon and having a thickness of 50 microns and a pore size of .02 microns was used.
To make the membrane forming solution, 50 ppm furfurol alcohol was added to water. To this solution was added 1% ethyl alcohol, 0.1% polyoxyethylene. Sodium hydroxide was then added to this solution to adjust the pH to 8 and xylenoblue was added as an indicator. The pump was activated and operated at a pressure of 3 kg/cm2. After approximately 2-3 minutes, small amounts of sulphuric acid were added to lower the pH and the indicator concentration was measured with a photometer. After approximately 30 minutes, the solution had a pH of approximately 3 and the concentration of indicator in the permeate water as compared with the concentration of indicator remaining in the feedwater was approximately 95%.
At this point, the pump was stopped and a solution of 1% ethyl alcohol, 5% glycerol and 1% formalin was introduced into the membrane. Example 2
The extrafiltrator in this example contained a polypropylene hollow fibre module having a membrane thickness of 50 microns and a pore size of .6 microns.
The membrane solution contained 50 ppm furol, .7% dibutic phthalate, water, acetone, ethyl sulphate, sodium dodecyl sulfonate and phenolphthalein. The solution was made by dissolving furol in acetone, dibutic phthalate and ethyl sulphate to form a first solution. This first solution was poured into water to achieve the above concentration and sodium dodecyl sulfonate was dissolved in the solution while adding phenolphthalein. The pump was turned on and operated at a pressure of approximately 3 kg/cm2. The pump was operated for approximately 60 minutes and the concentration of indicator measured using a photometer. After approximately 60 minutes the indicator concentration in the permeate was approximately 95% of that in the feedwater. The pump was stopped and the membrane was treated with a preserving solution containing 1% ethyl alcohol, 5% glycerol and 1% formalin in water.
It is to be understood that variations to the embodiment described above may be apparent to persons skilled in the relevant arts without departing from the spirit and scope of the invention as set out in the appended claims. It is to be understood that such variations or modifications are intended to be covered by this specification.

Claims

We CLAIM:
1. An ultrafiltration membrane formed on an extrafiltrator for use in a water purification system, said ultrafiltration membrane comprising: a membrane material selected from the group of resins consisting of furan, furfural, furfurone, furfuronal and furfuryl alcohol; said membrane having a thickness of from 50 microns to 40,000 microns; said membrane having pores with a diameter of from 5θA to lOOA; and, said membrane having been formed dynamically within the pores of said extrafiltrator.
2. An ultrafiltration filter as claimed in claim 1, wherein said membrane formation is achieved by passing a solution containing a membrane forming material, a solvent, a diluent, a plasticizer, a curing agent and a pore forming agent through said extrafiltrator; said extrafiltrator is made from a material selected from the group consisting of polypropylene, nylon, cellulose and aromatic amides; said extrafiltrator has a thickness of from 8 to 200 microns and a pore size of from .02 to 1 microns.
3. An ultrafiltration filter as claimed in claim 1 or 2, wherein said dynamically formed membrane material is a resin selected from the group consisting of furan resin, furfural resin, furfurone resin, furfuronal resin and furfuryl alcohol resin in a concentration of from 1 to 200 mg/1; said diluent is selected from the group consisting of lower alcohols and ketones in an amount of from 1 to 99% by volume of the membrane forming liquid; said plasticizer is phthalic phosphoric ester in a concentration of from 0.5 to 500 mg/1; said curing agent is selected from the group comprising benzene sulfonyl chloride, ethyl sulfate, sulphuric acid in an amount from 0.9 to 5% by volume of the membrane forming solution; said solvent is water in an amount of from
1 to 99% of said membrane forming solution; and, said pore forming agent is a neutral soluble inorganic salt in a concentration of from 20 to 1500 mg/1 and a surfactant in a concentration of from 20 to 1500
4. A method for forming an ultrafiltration membrane on an extrafiltrator, said method comprising the steps of: preparing a membrane forming solution by combining a membrane forming material, a solvent, a diluent, a plasticizer, a curing agent and a pore forming agent; and, passing said membrane forming solution through said extrafiltrator to cause a membrane to deposit within the pores of said extrafiltrator, to crosslink and to fixate in said pores.
5. A method according to claim 4 wherein: said membrane material is a resin selected from the group consisting of furan resin, furfural resin, furfurone resin, furfuronal resin and furfuryl alcohol resin in an amount of from 1 to 200 mg/1; said diluent is selected from the group consisting of lower alcohols and ketones in an amount of from 1 to 99% by volume of said membrane forming solution; said plasticizer is phthalic phosphoric ester in an amount of from 0.5 to 500 mg/1. said curing agent is selected from the group consisting of benzene sulfonyl chloride, ethyl sulfate and sulphuric acid in an amount of from 0.9 to 5% by volume of said membrane forming solution; said solvent is water in an amount of from 1 to 99% by volume of said membrane forming solution; and said pore forming agent is a neutral soluble inorganic salt in an amount of from 20 to 1500 mg/1 and a surfactant in an amount of from 20 to 1500 mg/1.
6. A method according to claim 5 wherein: said surfactant is selected from the group consisting of alkylsodium sulfate, quaternary ammonium salt and polyoxyethylene; and the pH of the membrane forming solution is adjusted during membrane deposition to gradually increase the amount of polymerization of the membrane forming material.
7. A method according to claim 6 wherein an indicator is further added to the membrane forming solution and the indicator concentration in the membrane forming solution permeating through the extrafiltrator is monitored to determine the completeness of membrane deposition.
8. A method according to claim 7 wherein: said extrafiltrator is a cellulose hollow fiber module having a thickness of about 50 microns and a pore size of about 0.02 microns; said surfactant is polyoxyethylene in an amount of about 1% by weight of the membrane forming solution; sodium hydroxide is added to the membrane forming solution to give an initial pH of approximately 8; and, during membrane deposition the pH of the membrane forming solution is decreased to approximately 3 by the addition of sulphuric acid.
9. A method for forming an ultrafiltration membrane on an extrafiltrator which is a polypropylene hollow fibre module having a thickness of about 50 microns and a pore size of about 6 microns, said method comprising the steps of: diluting furol with acetone, dibutic phthalate and ethyl sulfate to form a first solution which is subsequently combined with water to give a concentration of 50 ppm furol, .7% dibutic phthalate; 2% acetone and
1.5% ethyl sulfate; dissolving 1000 ppm sodium dodecyl sulfonate in said first solution and adding phenolphthalein to give a second solution; passing said second solution through said extrafiltrator at a pressure of about 3 kg/cm2; photometrically measuring the concentration of said indicator permeating through said extrafiltrator; ceasing passing of said second solution through said extrafiltrator when the concentration of indicator in said permeate reaches a desired value.
10. A method for purifying water using an ultrafiltration membrane deposited on an extrafiltrator, said method including the steps of: passing water through an extrafiltrator having an ultrafiltration membrane deposited thereon; and periodically stopping the flow of water into said extrafiltrator and allowing unfiltered water to drain from ultrafiltration membrane deposited on said extrafiltrator.
PCT/CA1990/000090 1989-03-18 1990-03-16 Ultrafiltration membrane WO1990011120A1 (en)

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CN89101659.7A CN1045756A (en) 1989-03-18 1989-03-18 Full-automatic dynamically forms the film water cleaning systems
EP89101659.7 1989-03-18

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US7025885B2 (en) 1998-11-23 2006-04-11 Zenon Environmental Inc. Water filtration using immersed membranes
US7842637B2 (en) 2008-05-23 2010-11-30 Lumimove, Inc. Electroactivated film with polymer gel electrolyte
US7993495B2 (en) 2005-06-21 2011-08-09 Crosslink Polymer Research, a division of Lumimove, Inc. Signal activated decontaminating coating
USRE42669E1 (en) 1995-08-11 2011-09-06 Zenon Technology Partnership Vertical cylindrical skein of hollow fiber membranes and method of maintaining clean fiber surfaces

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US7993495B2 (en) 2005-06-21 2011-08-09 Crosslink Polymer Research, a division of Lumimove, Inc. Signal activated decontaminating coating
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