Super-surface selective nanomembranes providing simultaneous high permeation flux and high selectivity
Superhydrophobic membrane structures having a beneficial combination of throughput and a selectivity. The membrane structure can include a porous support substrate; and a membrane layer adherently disposed on and in contact with the porous support substrate. The membrane layer can include a nanoporous material having a superhydrophobic surface. The superhydrophobic surface can include a textured surface, and a modifying material disposed on the textured surface. Methods of making and using the membrane structures.
1. A membrane structure comprising:
a porous support substrate
wherein the porous support substrate has a plurality of nanochannels,
wherein each of the plurality of nanochannels has a diameter of from 1 to 1000 nm,
wherein at least 50% of the plurality of nanochannels are oriented in a common direction,
wherein the common direction is parallel with a line intersecting the porous support substrate at an angle; and
a membrane layer adherently disposed on and in contact with the porous support substrate,
wherein the membrane layer comprises a nanoporous material having a superhydrophobic surface,
wherein the superhydrophobic surface comprises a textured surface, and a modifying material disposed on the textured surface,
wherein the modifying material is selected from the group consisting of an organic material, a polymeric material, and combinations thereof.
2. The membrane structure of claim 1 , wherein the membrane layer has a permeation flux of from 10-10,000 GPU.
3. The membrane structure of claim 1 , wherein the membrane layer has a permeation flux of greater than 1000 GPU.
4. The membrane structure of claim 1 , wherein the membrane layer has a selectivity of hydrophobic molecules to hydrophilic molecules of from 25/1 to 500/1.
5. The membrane structure of claim 1 , wherein the membrane layer has a selectivity of hydrophobic molecules to hydrophilic molecules of greater than 50/1.
6. The membrane structure of claim 1 , wherein the membrane layer has a permeation flux of greater than 1000 GPU, wherein the membrane layer has a selectivity of hydrophobic molecules to hydrophilic molecules of greater than 50/1, and wherein the nanoporous material comprises a plurality of pores having a pore size of from 10 to 50 nm.
7. The membrane structure of claim 1 , wherein the nanoporous material comprises a plurality of pores having a pore size of from 0.5 to 50 nm.
8. The membrane structure of claim 1 , wherein the porous support substrate comprises a ceramic material, a metallic material, a porous material, and combinations thereof.
9. The membrane structure of claim 1 , wherein the porous support substrate comprises one selected from the group consisting of porous ceramics, porous metals, porous steels, nitrides of any of the foregoing, oxynitrides of any of the foregoing, carbides of any of the foregoing, and combinations thereof.
10. The membrane structure of claim 1 , wherein the nanoporous material is one selected from the group consisting of a nanoporous glass, a nanoporous oxide, an anodized porous ceramic, and combinations thereof.
11. The membrane structure of claim 1 , wherein the nanoporous material comprises a plurality of hierarchical pores with diameters ranging from 2 to 10,000 nm, a plurality of nanopores each having a diameter of from 2 to 100 nm.
12. The membrane structure of claim 1 , wherein the nanoporous material has a thickness of from 100 nm-10,000 nm.
13. The membrane structure of claim 1 , wherein the nanoporous material is one selected from the group consisting of a phase-separated glass, a plurality of inorganic nanotubes, a plurality of diatomaceous earth particles, and combinations thereof.
14. The membrane structure of claim 13 , wherein the nanoporous material comprises the phase-separated glass, and wherein the phase-separated glass comprises at least one boron-containing glass composition.
15. The membrane structure of claim 14 , wherein the boron-containing glass composition is selected from the group consisting of a soda-lime glass, a phosphate glass, an alkali-free glass, a lead glass, a fluoride glass, a chalcogenide glass, an aluminosilicate, a borosilicate composition, and combinations thereof.
16. The membrane structure of claim 13 , wherein the nanoporous material comprises the plurality of inorganic nanotubes, and wherein the plurality of inorganic nanotubes comprise a ceramic selected from the group consisting of TiO 2 , alumina, silica, zirconia, hafnia, platinum, and combinations thereof.
17. The membrane structure of claim 13 , wherein the nanoporous material comprises the plurality of diatomaceous earth (DE) particles, and
wherein the nanoporous material is formed by a process comprising:
bonding the plurality of diatomaceous earth particles to the porous support substrate with a binder selected from the group consisting of a polymeric binder, a sol-gel binder, and combinations thereof;
etching the plurality of diatomaceous earth particles with an etchant selected from the group consisting of a solvent, an acid, and combinations thereof to produce the plurality of nanopores having an average size of from 0.5 to 100 nm; and
modifying the porous surface with a hydrophobic polymer/ligand material.
18. The membrane structure of claim 17 , wherein the step of bonding the plurality of diatomaceous earth particles to the porous support substrate with a binder comprises
preparing a powder-polymer hybrid material by combining the plurality of superhydrophobic DE particles with the binder; and
depositing the powder-polymer hybrid material onto the porous support substrate,
wherein the powder-polymer hybrid material comprises one selected from the group consisting of superhydrophobic diatomaceous earth particles, porous acrylic particles, and combinations thereof.
19. The membrane structure of claim 17 , wherein the polymer/ligand material comprises long chain hydrocarbon molecules or polymers containing hydrophobic functional groups selected from the group consisting of tri-methyl- terminal groups, perfluoro- terminal groups, and combinations thereof.
20. The membrane structure of claim 1 , wherein the organic material comprises a long-chain silane molecule having from 1 to 100 carbon atoms.
21. The membrane structure of claim 1 , wherein the organic material renders the textured surface of the nanoporous material superhydrophobic.
22. The membrane structure of claim 1 , wherein the organic material renders the textured surface of the nanoporous material oleophilic.
23. The membrane structure of claim 1 , wherein the organic material renders the textured surface of the nanoporous material oleophobic.
24. An apparatus comprising the membrane structure of claim 1 .
25. The apparatus of claim 24 , wherein the apparatus is selected from the group consisting of a pervaporation membrane, fuel cell, a gas separator, a size-exclusive separator, an oil-water separation membrane, a membrane reactor, a catalytic converter, and combinations thereof.
26. The membrane structure according to claim 1 , wherein the angle is from 0 to 180 degrees.
27. The membrane structure according to claim 1 , wherein the angle is from 45 to 135 degrees.