Thin polymer membrane for treatment of saline water

Patent metadata

Field	Value
Publication number	US-2020101427-A1
Application number	US-201916586245-A
Country	US
Kind code	A1
Filing date	Sep 27, 2019
Priority date	Sep 28, 2018
Publication date	Apr 2, 2020
Grant date	—

Abstract

An ultra high molecular weight polyethylene (UHMWPE) membrane has at least one nanoporous UHMWPE film, where each of the nanoporous UHMWPE film is biaxial oriented with a thickness of 0.1 to 12 μm and pores that exclude particles in excess of 10 nm with a total porosity of 65 to 75 percent. The nanoporous UHMWPE film can be coated or laminated by a hydrophilic polymer to form a Janus membrane and can be made with a multilayer composite structure. The UHMWPE membrane can be used in a device for molecular distillation (MD), reverse osmosis (RO), or forward osmosis (FO).

First claim

We claim:

1 . A membrane comprising ultra high molecular weight polyethylene (UHMWPE), the membrane comprising at least one nanoporous UHMWPE film, each of the nanoporous UHMWPE film being biaxial oriented with a thickness of 0.1 to 12 μm and pores that are exclusive to particles in excess of 10 nm with a total porosity of 65 to 75 percent.

2 . The membrane according to claim 1 , wherein the at least one nanoporous UHMWPE film comprises a plurality of nanoporous UHMWPE films.

3 . The membrane according to claim 2 , wherein the plurality of nanoporous UHMWPE films comprises three or more nanoporous UHMWPE films.

4 . The membrane according to claim 1 , wherein the nanoporous UHMWPE film has a thickness greater than 0.1 but less than 12 μm with an ultimate tensile strength of at least 400 MPa and a modulus of at least 1.4 GPa.

5 . The membrane according to claim 1 , wherein one nanoporous UHMWPE film is a hydrophilic polymer coated nanoporous UHMWPE film or a hydrophilic polymer laminated nanoporous UHMWPE film.

6 . The membrane according to claim 5 , wherein the hydrophilic polymer coated nanoporous UHMWPE film comprises a nanoporous UHMWPE film coated with polyvinyl alcohol, polyethylene oxide, or a polyethylene oxide-block-polypropylene oxide or other hydrophilic treatments.

7 . The membrane according to claim 5 , wherein the hydrophilic polymer laminated nanoporous UHMWPE film comprises a nanoporous UHMWPE film laminated to a hydrophilic nylon or other porous substrate.

8 . A device for performing desalination of salt water, comprising a UHMWPE comprising the membrane according to claim 1 .

9 . The device for performing desalination of salt water according to claim 8 , wherein the device is a membrane distillation (MD) device, a reverse osmosis (RO) device, or a forward osmosis (FO) device.

10 . The device for performing desalination of salt water according to claim 8 , wherein the UHMWPE comprising membrane is supported on a support.

11 . The device for performing desalination of salt water according to claim 8 , wherein the support is a porous carbon fiber plate or other porous rigid material.

12 . The device for performing desalination of salt water according to claim 8 , wherein the flux through the UHMWPE comprising membrane exceeds 100 LMH where the salt water is sea water having a temperature of 40° C. and the purified water on the opposite side of the UHMWPE comprising membrane has a temperature of 10° C. lower than the temperature of the salt water.

13 . The device for performing desalination of salt water according to claim 8 , further comprising a vacuum pump.

14 . A method of performing membrane distillation, comprising
supporting a membrane according to claim 1 that separates a salt solution feed chamber and a purified water receiving chamber; providing a salt solution to the salt solution feed chamber; providing heat to the salt solution to maintain a temperature of at least 40° C.; evacuating the purified water receiving chamber to a certain level vacuum; providing cooling to the purified water to maintain a temperature below the feed; optionally, applying pressure to the salt solution; transporting water vapor through the membrane at a flux of 100 LMH or more; and maintaining the vacuum by cooling of the purified water to at least 10° C. below the salt solution in the feed chamber.

15 . The method according to claim 14 , wherein the salt solution is sea water.

16 . The method according to claim 14 , wherein the salt solution is a fruit juice.

17 . The method according to claim 14 , wherein supporting the membrane comprises attaching the membrane to a carbon fiber plate or a rigid material.

18 . The method according to claim 14 , wherein the membrane comprises at least one nanoporous UHMWPE film.

19 . The method according to claim 18 , wherein at least one of the at least one nanoporous UHMWPE film is a hydrophilic polymer coated nanoporous UHMWPE film or a hydrophilic polymer laminated nanoporous UHMWPE film.

20 . The method according to claim 14 , wherein the membrane comprises four of the nanoporous UHMWPE films whereby the purified water with resistivity of no less than 10 MΩ·cm.

21 . The method according to claim 5 , wherein the nanoporous UHMWPE film is a hydrophilic polymer coated nanoporous UHMWPE film or a hydrophilic polymer laminated nanoporous UHMWPE film, whereby latent heat of vaporization is reduced by 1.5%.

Assignees

• Univ Hong Kong Sci & Tech

Inventors

• Gao Ping
• Sheng Ping
• Gu Qiao
• Zhang Qinghua
• Li Jin
• Li Runlai

Classifications

• B01D69/02

  characterised by their properties · CPC title

• B01D61/025

  Reverse osmosis; Hyperfiltration · CPC title

• A23L2/74

  using membranes, e.g. osmosis, ultrafiltration · CPC title

• C02F1/447

  by membrane distillation (distillation and evaporation without the use of membranes C02F1/04) · CPC title

• A23L2/085 Primary

  by osmosis, reverse osmosis, electrodialysis · CPC title