Thermo-responsive draw solute for forward osmosis and method for water desalination and purification using the same

Patent metadata

Field	Value
Publication number	US-9550728-B2
Application number	US-201214235192-A
Country	US
Kind code	B2
Filing date	Jul 27, 2012
Priority date	Jul 27, 2011
Publication date	Jan 24, 2017
Grant date	Jan 24, 2017

Abstract

The present invention relates to a thermo-responsive draw solute that can be applied to water desalination and purification based on forward osmosis. The thermo-responsive draw solute has a molar mass of 50 to 3000 g/mol and undergoes a phase transition at a temperature of 0° C. to 70° C. The thermo-responsive draw solute creates optimum conditions for the desalination of seawater and the purification of contaminated water based on forward osmosis. The present invention also relates to a method for water desalination and purification using the thermo-responsive draw solute. The method consumes little energy for water desalination or purification, is simple to apply to water desalination or purification, and enables separation of the draw solute in a very easy manner.

First claim

The invention claimed is:

1. A method for water desalination and purification using a thermo-responsive draw solute for forward osmosis, the method comprising:
1) bringing unpurified water into contact with a draw solution comprising the thermo-responsive draw solute at a higher concentration than the unpurified water through a semi-permeable membrane;
2) allowing clean water to flow from the unpurified water into the draw solution through the semi-permeable membrane by forward osmosis;
3) adjusting the temperature of the draw solution to or above the critical solution temperature of the thermo-responsive draw solute to cause a lower critical solution temperature (LCST) phase separation of the thermo-responsive draw solute from the draw solution; and
4) separating the clean water from the thermo-responsive draw solution.

2. The method according to claim 1 , wherein the thermo-responsive draw solute for forward osmosis has a molar mass of 50 to 3000 g/mol and undergoes a LCST phase transition at a temperature of 0° C. to 70° C.

3. The method according to claim 1 , wherein the thermo-responsive draw solute for forward osmosis is selected from the group consisting of:

and mixtures thereof.

4. The method according to claim 1 , wherein the semi-permeable membrane is a cellulose acetate or polyether sulfone semi-permeable membrane.

5. The method according to claim 1 , wherein the unpurified water is water comprising ions, colloids, microbes, water soluble molecules, insoluble organic molecules, or mixtures thereof.

6. The method according to claim 1 , wherein the draw solution is formed by dissolving phase-separated thermo-responsive draw solute.

7. A method for water desalination and purification using a thermo-responsive draw solute for forward osmosis, the method comprising:
1) bringing unpurified water into contact with a draw solution comprising the thermo-responsive draw solute at a higher concentration than the unpurified water through a semi-permeable membrane;
2) allowing clean water to flow from the unpurified water into the draw solution through the semi-permeable membrane by forward osmosis;
3) adjusting the temperature of the draw solution to or below the critical solution temperature of the thermo-responsive draw solute to cause an upper critical solution temperature (UCST) phase separation of the thermo-responsive draw solute from the draw solution;

and
4) separating the clean water from the thermo-responsive draw solution.

8. The method according to claim 7 , wherein the thermo-responsive draw solute has a molar mass of 50 to 3000 g/mol and undergoes an UCST phase transition at a temperature of 0° C. to 70° C.

9. The method according to claim 7 , wherein the thermo-responsive draw solute is selected from the group consisting of:

and mixtures thereof.

10. The method according to claim 7 , wherein the semi-permeable membrane is a cellulose acetate or polyether sulfone semi-permeable membrane.

11. The method according to claim 7 , wherein the unpurified water is water comprising ions, colloids, microbes, water soluble molecules, insoluble organic molecules, or mixtures thereof.

12. The method according to claim 7 , wherein the draw solution is formed by dissolving phase-separated thermo-responsive draw solute.

13. A method for water desalination and purification using a thermo-responsive draw solute for forward osmosis, the method comprising:
1) bringing unpurified water into contact with a draw solution comprising the thermo-responsive draw solute at a higher concentration than the unpurified water through a semi-permeable membrane;
2) allowing clean water to flow from the unpurified water into the draw solution through the semi-permeable membrane by forward osmosis;
3) adjusting the temperature of the draw solution to or below the critical solution temperature of the thermo-responsive draw solute to cause a phase transition of the thermo-responsive draw solute from the draw solution; and
4) separating the clean water from the draw solution,
wherein the thermo-responsive draw solute is selected from the group consisting of:

and mixtures thereof.

14. The method according to claim 13 , wherein the phase transition in element 3) results in phase separation of the thermo-responsive draw solute.

Assignees

• Lee Yan
• Noh Minwoo
• Mok Yeongbong
• Kim Heejin
• Lee Seonju
• Nakayama Daichi
• Univ Seoul Nat R & Db Found

Inventors

• Lee Yan
• Noh Minwoo
• Mok Yeongbong
• Kim Heejin
• Lee Seonju
• Nakayama Daichi

Classifications

• C02F2103/08

  Seawater, e.g. for desalination · CPC title

• Y02W10/37

  using solar energy · CPC title

• Y02A20/131

  Reverse-osmosis · CPC title

• C07C309/14

  containing amino groups bound to the carbon skeleton · CPC title

• C07C233/05 Primary

  having the nitrogen atoms of the carboxamide groups bound to hydrogen atoms or to acyclic carbon atoms · CPC title