Carbon nanotube immobilized super-absorbing membranes

Patent metadata

Field	Value
Publication number	US-9919274-B2
Application number	US-201615265573-A
Country	US
Kind code	B2
Filing date	Sep 14, 2016
Priority date	Sep 15, 2015
Publication date	Mar 20, 2018
Grant date	Mar 20, 2018

Abstract

Carbon nanotube (CNT) immobilized membranes for harvesting pure water from air include CNTs incorporated into a layer of super-absorbing polymer. The super-absorbing polymer may be cast over a porous substrate. The super-absorbing polymer binds strongly to water and generates water clusters while the CNTs are operable to interrupt the specific water-polymer and water-water interactions to generate more free water which permeates more easily through the membrane. Methods of forming the CNT immobilized membranes are provided. The CNT immobilized membranes disclosed herein exhibit improved water vapor extraction efficiency, water vapor removal and mass transfer coefficient.

First claim

What is claimed is:

1. A polymeric membrane comprising a porous substrate and a layer disposed on a surface of the porous substrate, the layer comprising a plurality of carbon nanotubes immobilized in a super-absorbent polymer.

2. The polymeric membrane according to claim 1 wherein the porous substrate comprises a porous polymeric material.

3. The polymeric membrane according to claim 2 wherein the porous substrate is selected from the group consisting of cellulose acetate, cellulose ester, polysulfone, polyether sulfone, polyacrilonitrile, polyamide, polyimide, polyethylene, polypropylene, polytetrafluoroethylene, polyvinylidene fluoride and polyvinylchloride.

4. The polymeric membrane according to claim 1 wherein the porous substrate comprises polypropylene.

5. The polymeric membrane according to claim 1 wherein the porous substrate comprises hollow fiber polypropylene.

6. The polymeric membrane according to claim 1 wherein at least one of the plurality of carbon nanotubes is single walled.

7. The polymeric membrane according to claim 1 wherein at least one of the plurality of carbon nanotubes is multi-walled.

8. The polymeric membrane according to claim 1 wherein at least one of the plurality of carbon nanotubes is carboxylated.

9. The polymeric membrane according to claim 1 wherein the super-absorbent polymer is selected from the group consisting of cross-linked poly(acrylamide-co-acrylic acid) and salts thereof and cross-linked sodium polyacrylate.

10. The polymeric membrane according to claim 1 wherein the super-absorbent polymer is poly(acrylamide-co-acrylic acid).

11. A method of making a carbon nanotube- immobilized membrane comprising the steps of dispersing a plurality of carbon nanotubes in water to form a carbon nanotube dispersion, dissolving a super-absorbent polymer in water to form a super-absorbent copolymer solution, adding the super-absorbent copolymer solution to the carbon nanotube dispersion to form a super-absorbent polymer-carbon nanotube mixture, applying the super-absorbent polymer-carbon nanotube mixture to a surface of a porous substrate and drying the super-absorbent polymer-carbon nanotube mixture.

12. The method according to claim 11 further comprising carboxylating at least one of the plurality of carbon nanotubes.

13. The method according to claim 11 further comprising pre-treating the porous substrate prior to the step of applying the super-absorbent polymer-carbon nanotube mixture thereto to enhance adhesion between the porous substrate and the super-absorbent polymer-carbon nanotube mixture.

14. The method according to claim 13 wherein the porous substrate comprises polypropylene and the step of pre-treating comprises hydrophilization.

15. The method according to claim 14 wherein the hydrophilization step comprises applying chromic acid to the porous substrate.

Assignees

• New Jersey Inst Technology

Inventors

• Mitra Somenath
• Roy Sagar

Classifications

• E03B3/28

  from humid air (condensing of vapours in general B01D5/00; dehumidification of air for air-conditioning F24F3/14) · CPC title

• B01D2325/12

  Adsorbents being present on the surface of the membranes or in the pores · CPC title

• B01D69/148

  Organic/inorganic mixed matrix membranes · CPC title

• B01D69/105

  Support pretreatment · CPC title

• B01D5/00

  Condensation of vapours; Recovering volatile solvents by condensation (B01D8/00 takes precedence; condensers F28B) · CPC title