METHODS OF MAKING GRAPHENE OXIDE NANOFILTERS

• US 20190275470A1
• Filed: 03/07/2018
• Published: 09/12/2019
• Est. Priority Date: 03/07/2018
• Status: Active Grant

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Palo Alto Research Center, Inc. (Xerox Holdings Corp.)
• Inventors: Biegelsen, David K.
• Granted Patent: US 10,449,497 B2
• Time in Patent Office: Days
• CPC Class Codes: B01D 2323/10 Specific pressure applied
• CPC Class Codes: B01D 2323/50 Control of the membrane preparation process
• CPC Class Codes: B01D 2325/04 Characteristic thickness
• CPC Class Codes: B01D 2325/20 Specific permeability or cut-off range
• CPC Class Codes: B01D 61/027 Nanofiltration
• CPC Class Codes: B01D 67/0039 Inorganic membrane manufacture
• CPC Class Codes: B01D 67/00416 by deposition by filtration through a support or base layer
• CPC Class Codes: B01D 67/0088 Physical treatment with compounds, e.g. swelling, coating or impregnation
• CPC Class Codes: B01D 69/105 Support pretreatment
• CPC Class Codes: B01D 71/0211 Graphene or derivates thereof
• CPC Class Codes: B01D 71/024 Oxides
• CPC Class Codes: C01B 32/198 Graphene oxide
• CPC Class Codes: Y02A 20/131 Reverse-osmosis

Abstract

Nanofiltration of aqueous solutions or other water-based fluids in various applications, such as desalination, dialysis, seawater purification, for example, may be enhanced through precisely controlling a filtration cutoff within graphene oxide nanofilters. By initially compressing and constraining the stacked thickness of multiple graphene oxide layers deposited between porous substrates, the interlayer gap size, and thus, the filtration cutoff may be adjusted and optimized.

Claims

1. A method comprising:

depositing graphene oxide layers on a first porous surface;

adding a second porous surface atop the graphene oxide;

applying pressure to the first and second porous surfaces up to a yield point of the graphene oxide layers beyond which the layers become incompressible;

correlating the distance between the first and second porous surfaces to an interlayer gap size between the graphene oxide layers; and

determining a filtration cutoff for a filter using the porous surfaces based upon the interlayer gap size.

2. The method of claim 1, wherein depositing graphene oxide layers includes depositing graphene oxide flakes.

3. The method of claim 1, wherein depositing graphene oxide layers is accomplished using vacuum filtration.

4. The method of claim 1, further comprising:

determining how many layers of graphene oxide are deposited.

5. The method of claim 4, wherein determining how many layers of graphene oxide are deposited includes determining a compressed thickness of the graphene oxide layers.

7. The method of claim 1, further comprising:

adding a first support plate below the first porous surface; and

adding a second support plate above the second porous surface.

8. The method of claim 7, wherein applying pressure to the first and second porous surfaces includes decreasing a distance between the first and second support plates.

9. The method of claim 1, wherein applying pressure to the first and second porous surfaces includes decreasing a distance between the first and second porous surfaces.

10. The method of claim 1, further comprising setting a predetermined distance between the first and second porous surfaces prior to applying pressure.

11. The method of claim 1, further comprising:

dividing the first and second porous surfaces and deposited graphene oxide layers into two or more stacks, wherein each stack includes the first and second porous surfaces and deposited graphene oxide layers.

6. (canceled)

12. A method comprising:

depositing layers of graphene oxide between a first and second support plate to form a filter module;

compressing the first and second support plates;

determining the thickness of the compressed graphene oxide layers;

immersing the filter module in water;

determining a separation distance based on at least one of a desired filtration cutoff and a desired interlayer gap size; and

separating the first and second support plates by the separation distance.

13. The method of claim 12, wherein determining the thickness of the compressed graphene oxide layers includes determining how many graphene oxide layers have been deposited.

14. The method of claim 12, wherein determining a separation distance includes:

separating the first and second support plates by a set of test distances,

determining at least one of an actual filtration cutoff and an actual interlayer gap size, resulting from the test distance, and

mapping each test distance against at least one of each determined actual filtration cutoff and actual interlayer gap size.

15. The method of claim 12, further comprising:

determining the separation distance based on at least one of the determined graphene oxide layers'"'"' thickness, an actual interlayer gap size, and a desired filtration cutoff.

16. The method of claim 12, wherein separating the first and second support plates is achieved through adjusting a fine pitched screw.

17. The method of claim 12, wherein separating the first and second support plates is achieved through actuating an inch worm piezo.

18. The method of claim 12, wherein separating the first and second support plated is achieved pneumatically.

19. The method of claim 12, further comprising:

inserting a first porous substrate filter between the graphene oxide layers and first support plate; and

inserting a second porous substrate filter between the graphene oxide layers and second support plate.

20. The method of claim 12, further comprising:

adjusting the separation distance between the first and second support plates after separating the first and second support plates initially.