Nanofiltration membrane and method of manufacturing a nanofiltration membrane

Patent metadata

Field	Value
Publication number	US-10525423-B2
Application number	US-201414783815-A
Country	US
Kind code	B2
Filing date	Apr 10, 2014
Priority date	Apr 10, 2013
Publication date	Jan 7, 2020
Grant date	Jan 7, 2020

Abstract

A nanofiltration membrane comprising a selective layer comprising or consisting of poly(amide-imide) cross-linked with polyallylamine is provided. A method of manufacturing a nanofiltration membrane and use of a nanofiltration membrane in a water softening process that is carried out at a low pressure of less than about 2 bar are also provided.

First claim

The invention claimed is:

1. A multi-layer hollow fiber nanofiltration membrane comprising
a) an inner layer of polyethersulfone; and
b) an outer layer of a positively charged selective layer comprising
a fiber substrate of poly(amide-imide) cross-linked only on its outer layer with polyallylamine, wherein the fiber substrate of poly(amide-imide) was treated with glycerol before cross-linking.

2. The multi-layer hollow fiber nanofiltration membrane according to claim 1 , wherein the poly(amide-imide) has general formula (I)

wherein
R a at each occurrence is independently selected from the group consisting of optionally substituted C 1 -C 20 alkyl, optionally substituted C 2 -C 20 alkenyl, optionally substituted C 2 -C 20 alkynyl, optionally substituted monocyclic, condensed polycyclic or bridged polycyclic C 5 -C 20 aryl, optionally substituted C 3 -C 20 mono-, or poly-cycloalkyl, optionally substituted C 3 -C 20 mono-, or poly-cycloalkenyl; optionally substituted 2-20-membered heteroalkyl, optionally substituted 2-20-membered heteroalkenyl, optionally substituted 2-20-membered heteroalkynyl, optionally substituted 5-20-membered monocyclic, condensed polycyclic or bridged polycyclic heteroaryl, optionally substituted 3-20-membered mono-, or poly-heterocycloalkyl, and optionally substituted 3-20-membered mono-, or poly-heterocycloalkenyl; and
n is an integer in the range from 20 to 1000.

3. The multi-layer hollow fiber nanofiltration membrane according to claim 2 , wherein R a at each occurrence is independently selected from the group consisting of optionally substituted monocyclic, condensed polycyclic or bridged polycyclic C 5 -C 20 aryl, and optionally substituted 5-20-membered monocyclic, condensed polycyclic or bridged polycyclic heteroaryl.

4. The multi-layer hollow fiber nanofiltration membrane according to claim 2 , wherein R a in each monomer is independently selected from the group consisting of

and isomers thereof.

5. The multi-layer hollow fiber nanofiltration membrane according to claim 4 , wherein ratio of monomers with

and isomers thereof to monomers with

and isomers thereof is about 7:3.

6. The multi-layer hollow fiber nanofiltration membrane according to claim 1 , wherein the poly(amide-imide) has general formula (II)
H-[(A) p -(B) q -(A) s -(B) t ] m —NH 2   (II)

wherein
A is

B is

each of p, q, s, and t is independently 0, or an integer in the range of about 1 to about 10, with the proviso that at least one of p and s, and at least one of q and t is not 0; and
m is an integer in the range of about 20 to 1000.

7. The multi-layer hollow fiber nanofiltration membrane according to claim 1 , wherein the polyallylamine is formed from polymerization reaction comprising aliphatic ethylenically unsaturated alkylamine monomers having general formula (III)
R b —C═C—R c —NH 2   (III)

wherein R b is optionally substituted C 1 -C 10 alkyl and R c is (CH 2 ) r , wherein r is an integer in the range of 1 to 10.

8. The multi-layer hollow fiber nanofiltration membrane according to claim 1 , wherein molecular weight of the polyallylamine is in the range of about 8000 Da to about 25000 Da.

9. The multi-layer hollow fiber nanofiltration membrane according to claim 1 , wherein thickness of the positively charged selective layer is in the range of about 20 μm to about 50 μm.

10. The multi-layer hollow fiber nanofiltration membrane according to claim 1 , wherein the positively charged selective layer comprising a fiber substrate of poly(amide-imide) cross-linked only on its outer layer with polyallylamine comprises units of general formula (IV)

11. A method of manufacturing a multi-layer hollow fiber nanofiltration membrane comprising an inner layer of polyethersulfone and an outer layer of a positively charged selective layer comprising a fiber substrate of poly(amide-imide) cross-linked only on its outer layer with polyallylamine, the method comprising:
a) providing a multi-layer hollow fiber nanofiltration membrane comprising an inner layer of polyethersulfone and an outer layer comprising a fiber substrate of poly(amide-imide), and
b) treating the fiber substrate of poly(amide-imide) with glycerol before cross-linking the outer layer comprising the fiber substrate of poly(amide-imide) with polyallylamine to form a positively charged selective layer comprising a fiber substrate of poly(amide-imide) cross-linked only on its outer layer with polyallylamine.

12. The method according to claim 11 wherein the poly(amide-imide) has general formula (I)

wherein
R a at each occurrence is independently selected from the group consisting of optionally substituted C 1 -C 20 alkyl, optionally substituted C 2 -C 20 alkenyl, optionally substituted C 2 -C 20 alkynyl, optionally substituted monocyclic, condensed polycyclic or bridged polycyclic C 5 -C 20 aryl, optionally substituted C 3 -C 20 mono-, or poly-cycloalkyl, optionally substituted C 3 -C 20 mono-, or poly-cycloalkenyl; optionally substituted 2-20-membered heteroalkyl, optionally substituted 2-20-membered heteroalkenyl, optionally substituted 2-20-membered heteroalkynyl, optionally substituted 5-20-membered monocyclic, condensed polycyclic or bridged polycyclic heteroaryl, optionally substituted 3-20-membered mono-, or poly-heterocycloalkyl, and optionally substituted 3-20-membered mono-, or poly-heterocycloalkenyl; and
n is an integer in the range from 20 to 1000.

13. The method according to claim 11 , wherein the positively charged selective layer comprising a fiber substrate of poly(amide-imide) cross-linked only on its outer layer with polyallylamine comprises units of general formula (IV)

14. The method according to claim 11 , wherein the multi-layer hollow fiber membrane is prepared by co-spinning with a triple orifice spinneret comprising
a) extruding a bore liquid through an inner channel of the triple orifice spinneret;
b) extruding an inner doping liquid through a middle channel of the triple orifice spinneret, the inner doping liquid comprising 10 to 17 wt % polyethersulfone, 10 to 15 wt % poly(ethylene glycol), 2 to 7 wt % lithium chloride, and 61 to 78 wt % n-methyl-2-pyrrolidone; and
c) extruding an outer doping liquid through an outer channel of the triple orifice spinneret, the outer doping liquid comprising 15 to 20 wt % polyamide-imide and 65 to 85 wt % n-methyl-2-pyrrolidone.

15. The method according to claim 14 , wherein co-spinning with a triple orifice spinneret is carried out at a temperature in the range of about 20° C. to about 30° C.

16. The method according to claim 11 , whe

Assignees

• Univ Nanyang Tech
• Evoqua Water Tech Pte Ltd

Inventors

• Wang Rong
• Shi Lei
• Setiawan Laurentia

Classifications

• B01D71/76

  Macromolecular material not specifically provided for in a single one of groups B01D71/08 - B01D71/74 (rubbers in general B01D71/24) · CPC title

• B01D67/0006

  by chemical reactions (in-situ polymerisation, polycondensation, cross-linking or reaction for manufacturing composite membranes B01D69/125) · CPC title

• B29C48/022

  characterised by the choice of material · CPC title

• B01D71/68

  Polysulfones; Polyethersulfones · CPC title

• B29C48/21

  the layers being joined at their surfaces · CPC title