ELECTROCHEMICAL CARBON NANOTUBE FILTER AND METHOD

• US 20120234694A1
• Filed: 04/04/2012
• Published: 09/20/2012
• Est. Priority Date: 01/25/2011
• Status: Active Grant

• Current Assignee: President and Fellows of Harvard College (Harvard Corporation)
• Original Assignee: President and Fellows of Harvard College (Harvard Corporation)
• Inventors: Vecitis, Chad D., Van Fossen, Kirsten
• Granted Patent: US 9,827,517 B2
• Time in Patent Office: Days
• US Class Current: 205/747
• CPC Class Codes: B01D 2239/065 More than one layer present in the filtering material apparatus incorporating such gas filtering material B01D2275/10
• CPC Class Codes: B01D 35/06 Filters making use of electricity or magnetism ultrafiltration, microfiltration B01D61/14; electrodialysis, electro-osmosis B01D61/42; devices comprising filters and magnetic separators B03C1/30
• CPC Class Codes: B01D 39/2055 Carbonaceous material solid sorbent compositions comprising free carbon B01J20/20
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C02F 1/4672 by electrooxydation

Abstract

A filtration apparatus and filtration method can be used to reduce at least one contaminant (e.g., organic molecules, ions and/or biological microorganisms) in an aqueous fluid. The filtration apparatuses and methods of the invention can separate at least one contaminant from an aqueous fluid and/or oxidize at least one contaminant. In operation, an aqueous fluid is flowed through a filtration apparatus comprising a porous carbon nanotube filter material at an applied voltage. In some embodiments, the filtration apparatus described herein can be used for dead-end filtration. In some embodiments, the filtration apparatus described herein can be used for cross-over filtration.

Claims

1. A filtration apparatus, comprising:

a housing forming a chamber having a plane, the chamber including an inlet for receiving an input fluid, a first outlet for releasing fluid, and a second outlet for releasing filtered fluid, wherein the inlet and the first outlet are disposed on a first side of the plane, and the second outlet is disposed on a second side of the plane;

a filter positioned along the plane between the inlet and the second outlet, the filter comprising at least one porous polymer layer disposed between a first porous carbon nanotube filter material and a second porous carbon nanotube filter material;

a first conducting connector positioned along the plane between the inlet and the carbon nanotube-based filter; and

a second conducting connector positioned along the plane between the carbon nanotube-based filter and the second outlet.

2. The apparatus of claim 1, wherein the first conducting connector is in contact with a portion of the first porous carbon nanotube filter material.

3. The apparatus of claim 1, wherein the second conducting connector is in contact with a portion of the second porous carbon nanotube filter material.

4. The apparatus of claim 1, wherein at least one of the first conducting connector and the second conducting connector has a thickness of about 100 μ

m to about 150 μ

m.

5. The apparatus of claim 1, wherein the first conducting connector and the second conducting connector are electrically separated from each other to prevent a short circuit.

6. The apparatus of claim 5, wherein the first conducting connector and the second conducting connector each comprises at least one hole designed for a peg to align the first conducting connector and the second conducting connector with the filter.

7. The apparatus of claim 6, wherein a rim of the hole is coated with an electrically-insulting layer.

8. The apparatus of claim 6, wherein the peg is an electrically-insulating peg.

9. The apparatus of claim 1, wherein at least one of the first conducting connector and the second conducting connector includes titanium.

10. The apparatus of claim 1, wherein a flux through the porous polymer layer is at least 70% of a flux through the first porous carbon nanotube filter material or the second porous carbon nanotube filter material.

11. The apparatus of claim 10, wherein the porous polymer layer has a pore size of about 0.01 μ

m to about 5 μ

m.

12. The filtration apparatus of claim 1, wherein the first and the second porous carbon nanotube filter materials comprise undoped carbon nanotubes, nitrogen-doped carbon nanotubes, boron-doped carbon nanotubes, fluorine-doped carbon nanotubes or any combinations thereof.

13. The filtration apparatus of claim 12, wherein the carbon nanotubes are multi-walled carbon nanotubes.

14. The filtration apparatus of claim 13, wherein at least a portion of the carbon nanotubes are modified by at least one processing treatment.

15. The filtration apparatus of claim 14, wherein said at least one processing treatment is selected from a group consisting of calcination, acid treatment, polymer coating, addition of an electrocatalyst, addition of at least one functional group, and any combinations thereof.

16. The filtration apparatus of claim 1, wherein the first and the second porous carbon nanotube filter material have an average pore size of at least about 0.5 nm.

17. The filtration apparatus of claim 16, wherein the first and the second porous carbon nanotube filter material have a specific surface area of about 80 m²/g to about 120 m²/g.

18. A method for reducing at least one contaminant in a fluid, the method comprising:

providing

a filter extending along a plane between an inlet and a second outlet, the filter comprising at least one porous polymer layer disposed between a first porous carbon nanotube filter material and a second porous carbon nanotube filter material;

a first conducting connector positioned along the plane between the inlet and the filter, wherein the first conducting connector connects to the first porous carbon nanotube filter material; and

a second conducting connector positioned along the plane between the filter and the second outlet, wherein the second conducting connect connects to the second porous carbon nanotube filter material;

connecting the first conducting connector to a positive pole of a voltage source;

connecting the second conducting connector to a negative pole of the voltage source;

applying a voltage from the voltage source;

flowing a fluid parallel to a first surface of the filter from the inlet, wherein a first portion of the fluid flows across the filter separating at least one contaminant from the fluid, whereby the first portion of the fluid exits through the second outlet, and a second portion of the fluid exits through a first outlet, thereby reducing the at least one contaminant from the fluid.

19. The method of claim 18, wherein the fluid is an aqueous fluid.

20. The method of claim 19, wherein the aqueous fluid is water to be filtered.

21. The method of claim 19, wherein the aqueous fluid is a biological fluid.

22. The method of claim 19, wherein the aqueous fluid includes the at least one contaminant selected from organic molecules, ions, biological microorganisms, or a combination thereof.

23. The method of claim 18, wherein the second portion of the fluid existing through the first outlet is directed to flow into the inlet.

24. The method of claim 18, wherein the voltage generated by the voltage source is not greater than 10 volts.

25. A filter comprising at least one first porous polymer layer disposed between a first porous carbon nanotube filter material and a second porous carbon nanotube filter material.

26. The filter of claim 25, further comprising a second porous polymer layer disposed between the first porous carbon nanotube filter material and a third porous carbon nanotube filter material.

27. The filter of claim 25, further comprising a third porous polymer layer disposed between the second porous carbon nanotube filter material and a fourth porous carbon nanotube filter material.

28. The filter of claim 25, wherein said at least one porous polymer layer includes polyvinylidene fluoride (PVDF).