Nanofiber-containing membrane, a composite membrane, a process for producing them and their use

• US 8,403,151 B2
• Filed: 03/31/2010
• Issued: 03/26/2013
• Est. Priority Date: 01/04/2010
• Status: Active Grant

• Current Assignee: Taiwan Textile Research Institute
• Original Assignee: Taiwan Textile Research Institute
• Inventors: Huang, Cheng-Chiang, Cheng, Tai-Hong
• Primary Examiner(s): FORTUNA, ANA M
• Application Number:
  US12/751,644
• Publication Number:
  US 20110163035A1
• Time in Patent Office: 1,091 Days
• Field of Search: 210/500.43, 210/508, 210/505, 264/465, 264/466, 428/292.1, 428/414, 428/401, 442/327
• US Class Current: 210/500.43
• CPC Class Codes: B01D 2323/39 Electrospinning
• CPC Class Codes: B01D 2325/02 Details relating to pores or porosity of the membranes
• CPC Class Codes: B01D 2325/0283 Pore size
• CPC Class Codes: B01D 67/0002 Organic membrane manufacture
• CPC Class Codes: B01D 67/0093 Chemical modification
• CPC Class Codes: B01D 67/00931 by introduction of specific groups after membrane formation, e.g. by grafting
• CPC Class Codes: B01D 69/02 characterised by their properties
• CPC Class Codes: B01D 69/10 Supported membranes; Membrane supports
• CPC Class Codes: B01D 69/107 Organic support material
• CPC Class Codes: B01D 71/42 Polymers of nitriles, e.g. polyacrylonitrile
• CPC Class Codes: B01D 71/421 Polyacrylonitrile
• CPC Class Codes: B01D 71/82 characterised by the presence of specified groups, e.g. introduced by chemical after-treatment
• CPC Class Codes: C02F 1/444 by ultrafiltration or microfiltration
• CPC Class Codes: D01D 5/0007 Electro-spinning non-woven fabrics produced by electro-spinning D04H1/728
• CPC Class Codes: D01D 5/003 the material being a polymer solution or dispersion D01D5/0053 takes precedence
• CPC Class Codes: Y10T 156/10 Methods of surface bonding and/or assembly therefor
• CPC Class Codes: Y10T 428/249924 Noninterengaged fiber-containing paper-free web or sheet which is not of specified porosity
• CPC Class Codes: Y10T 442/60 Nonwoven fabric [i.e., nonwoven strand or fiber material]

Abstract

A nanofiber-containing membrane has a specific surface area of 0.1 to 1000 m²/g, porosity of 10 to 99.5% and a pore size of 0.01 to 10 μm. This provides a nanofiber-containing membrane having properties of high specific surface area, high porosity, nanoscale pore size, high pore uniformity and so on. A process for producing a nanofiber-containing membrane comprising producing a membrane from a polymer solution by electrospinning technology under optimal operation conditions.

Claims

1. A nanofiber-containing membrane, wherein the membrane has a specific surface area of 0.1 to 1000 m²/g, porosity of 10 to 99.5% and a pore size of 0.01 to 10 μ

m, wherein the surface of the membrane has a carboxy-functional group density of 0.1 to 30 meq/g.

2. The membrane of claim 1, which can be operated at a temperature of up to 300°

C.

3. The membrane of claim 1, wherein the diameter of the nanofiber is between 10 to 500 nm.

4. The membrane of claim 1, wherein the nanofiber consists of a polymer having cyano groups and the cyano groups of the polymer are partially or fully modified to carboxy groups.

5. The membrane of claim 4, wherein the polymer having the cyano groups is polyacrylonitrile or copolymers thereof.

6. The membrane of claim 4, wherein an inner side of the fiber contains cyano groups.

7. A process for producing a nanofiber containing membrane of claim 1, wherein the membrane is produced by an electrospinning process from a polymer solution, wherein the electrospinning process is operated by setting a collector to have a rotation of 360 degrees, using a two-component nozzle and operating the nozzle in left-right movement, or the electrospinning process is operated by a rotating cylinder without a nozzle.

8. The process of claim 7, wherein the membrane produced by a process according to claim 7 is subjected to alkalization hydrolysis treatment.

9. The process of claim 8, wherein the polymer solution is a solution of 5 to 30 (weight/volume) % of a polymer having cyano groups in a solvent.

10. The process of claim 9, wherein the polymer is polyacrylonitrile or copolymers thereof.

11. The process of claim 8, wherein during the electrospinning process, the voltage is 5 to 70 kV, the rotation speed of the collector is 0 to 100 cm/sec, the electrospinning distance is 3 to 30 cm, the feeding rate is 0.01 to 10 cc/hr and the left-right movement is 0 to 12 times/min.

12. The process of claim 8, wherein the alkalization hydrolysis treatment is performed by placing the membrane in an alkaline solution, and optionally applying ultrasonics during the alkalization hydrolysis treatment.

13. The process of claim 12, wherein the concentration of the alkaline solution is 0.1 to 30N;

the temperature is 4 to 150 ; and

the alkaline hydrolysis treatment time lasts for 1 to 600 min.

14. The process of claim 12, wherein the alkaline solution comprises a NaOH solution or a KOH solution.

15. The process of claim 12, wherein the strength of the ultrasonics applied is 10 to 100 KHz.

16. A composite membrane comprising a substrate, which is characterized in that one or two sides of the substrate have a membrane according to claim 1.

17. Use of a membrane according to claim 1 for the treatment of a heavy metal and an organic substance in a waste water, the filtration of the bacterial, the purification of protein and the separation of the micro-solid, comprising:

contacting the membrane with wastewater or a solution to be treated.

18. Use of a composite membrane according to claim 16 for the treatment of a heavy metal and an organic substance in a waste water, the filtration of the bacterial, the purification of protein and the separation of the micro-solid, comprising:

contacting the membrane with wastewater or a solution to be treated.

19. A process for producing a composite membrane,

which comprises the following steps of:

(1) adhering one or two membranes according to claim 1 to one or two sides of

(1) a substrate, and

(2) treating the composite membrane by an alkalization hydrolysis treatment, treatment.

20. The process of claim 19, the nanofiber of the membrane according to claim 1 consists of polyacrylonitrile or copolymers thereof.

21. The process of claim 19, wherein in step (1), the membrane is adhered to the substrate by hot-pressing at 25 to 150 for 0 to 30 min.

22. The process of claim 19, wherein the alkalization hydrolysis treatment in step (2) is performed by placing the membrane in an alkaline solution, and optionally applying ultrasonics during the alkalization hydrolysis treatment.

23. The process of claim 22, wherein the concentration of the alkaline solution is 0.1 to 30 N;

the temperature is 4 to 150 ; and

the alkaline hydrolysis treatment time lasts for 1 to 600 min.

24. The process of claim 22, wherein the alkaline solution comprises a NaOH solution or a KOH solution.

25. The process of claim 22, wherein the ultrasonics is applied at strength of 10 to 100 KHz.