Reverse osmosis composite membrane and method for manufacturing reverse osmosis composite membrane

Patent metadata

Field	Value
Publication number	US-10376847-B2
Application number	US-201615555916-A
Country	US
Kind code	B2
Filing date	Mar 29, 2016
Priority date	Mar 31, 2015
Publication date	Aug 13, 2019
Grant date	Aug 13, 2019

Abstract

A reverse osmosis composite membrane includes: a porous support; and a reverse osmosis membrane arranged on the porous support and containing a crosslinked polyamide and carbon nanotubes. The reverse osmosis membrane contains the carbon nanotubes that are disentangled in the crosslinked polyamide. A distribution of closest distances between the carbon nanotubes in the reverse osmosis membrane has a peak that is within a range of a thickness of the reverse osmosis membrane, and a half width of the peak is equal to or less than the thickness of the reverse osmosis membrane.

First claim

The invention claimed is:

1. A reverse osmosis composite membrane, comprising:
a porous support; and
a reverse osmosis membrane arranged on the porous support and containing a crosslinked polyamide and carbon nanotubes,
the reverse osmosis membrane containing disentangled carbon nanotubes in the crosslinked polyamide;
a distribution of closest distances between the carbon nanotubes in the reverse osmosis membrane having a peak that is within a range of a thickness of the reverse osmosis membrane; and
a half-width of the peak being equal to or less than the thickness of the reverse osmosis membrane.

2. The reverse osmosis composite membrane according to claim 1 , wherein the disentangled carbon nanotubes form a continuous three-dimensional structure through the crosslinked polyamide.

3. The reverse osmosis composite membrane according to claim 1 ,
wherein the crosslinked polyamide is a crosslinked aromatic polyamide; and
wherein the reverse osmosis membrane contains a molecularly-oriented crosslinked aromatic polyamide configured to cover the carbon nanotubes.

4. The reverse osmosis composite membrane according to claim 1 , wherein a content of the carbon nanotubes in the reverse osmosis membrane is 5 mass % or more and 30 mass % or less.

5. The reverse osmosis composite membrane according to claim 1 , wherein the distribution is a normal distribution.

6. The reverse osmosis composite membrane according to claim 1 , wherein the carbon nanotubes have an average diameter of 5 nm or more and 30 nm or less.

7. The reverse osmosis composite membrane according to claim 3 , wherein the molecularly-oriented crosslinked aromatic polyamide forms a layer on a surface of each of the carbon nanotubes, the layer having a thickness of 1 nm or more and 50 nm or less.

8. The reverse osmosis composite membrane according to claim 1 ,
wherein the reverse osmosis composite membrane has a permeate flux of 0.8 m 3 /(m 2 ·day·MPa) or more and a NaCl rejection rate of 95% or more when an aqueous solution of NaCl having a pH of 7, a temperature of 23° C., and a concentration of 2,000 ppm is supplied at an operating pressure of 1.55 MPa; and
wherein the reverse osmosis composite membrane has a reduction rate of the NaCl rejection rate of less than 10% after having been immersed in an aqueous solution of sodium hypochlorite having a pH of 9±0.5, a temperature of 23° C., and a concentration of 200 ppm for 24 hours.

9. The reverse osmosis composite membrane according to claim 1 , wherein the reverse osmosis composite membrane has a reduction rate of a permeate flux of less than 35% after having been brought into contact with an aqueous solution containing bovine serum albumin at a concentration of 200 ppm for 72 hours.

Assignees

• Univ Shinshu

Inventors

• Endo Morinobu
• Noguchi Toru
• Inukai Shigeki

Classifications

• B01D2323/40

  in-situ membrane formation · CPC title

• B01D71/56

  Polyamides, e.g. polyester-amides · CPC title

• B01D67/0006

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

• B01D2325/20

  Specific permeability or cut-off range · CPC title

• B01D69/148 Primary

  Organic/inorganic mixed matrix membranes · CPC title