Membranes for fluid separation
Membranes, methods of making the membranes, and methods of using the membranes are described herein. The membranes can comprise a gas permeable support and a continuous phase comprising a selective inorganic material disposed within the gas permeable support. In some embodiments, the membranes can exhibit a CO 2 :N 2 selectivity of at least 10 at 24° C. The membranes can be bendable, such that when the membranes are wrapped around a 1.5-inch diameter cylinder and returned to a planar conformation, the CO 2 :N 2 selectivity of the membranes is at least 25% of the CO 2 :N 2 selectivity of the membranes prior to having been wrapped around the cylinder.
1. A method of making alumino-silicate nanoparticles comprising:
(a) heating a first mixture comprising a silicon source, an aluminum source, a base, an organic agent, and a first solvent to produce a first population of alumino-silicate nanoparticles dispersed in a first supernatant;
(b) separating the first population of inorganic nanoparticles from the first supernatant;
(c) adding a base to the first supernatant to form a second mixture;
(d) heating the second mixture to produce a second population of alumino-silicate nanoparticles dispersed in a second supernatant; and
(e) separating the second population of inorganic nanoparticles from the second supernatant;
wherein the method comprises repeating steps (c) and (d) prior to performing step (e); and
wherein the first population of alumino-silicate nanoparticles and the second population of alumino-silicate nanoparticles each have an average particle size of 100 nm or less.
2. The method of claim 1 , wherein step (d) further comprises concentrating the second supernatant to form a concentrated supernatant, and diluting the concentrated supernatant the reform the second supernatant.
3. The method of claim 2 wherein step (d) further comprises concentrating the second supernatant to form a concentrated supernatant, heating the concentrated supernatant, and diluting the concentrated supernatant the reform the second supernatant.
4. The method of claim 1 , wherein steps (c) and (d) are repeated at least 5 times prior to performing step (e).
5. The method of claim 1 , wherein steps (c) and (d) are repeated until the yield of the second population of alumino-silicate nanoparticles is at least 75%.
6. The method of claim 2 , wherein concentrating the second supernatant comprises removing a portion of the first solvent.
7. The method of claim 6 , wherein the portion of first solvent removed is from 20% to 70% by volume of the second supernatant.
8. The method of claim 2 , wherein diluting the concentrated supernatant comprises adding a second solvent to the concentrated supernatant.
9. The method of claim 8 , wherein the second solvent added to the concentrated supernatant is from 20% to 70% by volume of the second supernatant.
10. The method of claim 8 , wherein the second solvent comprises water.
11. The method of claim 8 , wherein the second solvent further comprises a base.
12. The method of claim 1 , wherein the first solvent comprises water.
13. The method of claim 1 , wherein the silicon source comprises tetraethylorthosilane, colloidal silica, disodium metasilicate, or combinations thereof.
14. The method of claim 1 , wherein the base is selected from sodium hydroxide, potassium hydroxide, and combinations thereof.
15. The method of claim 1 , wherein the organic agent comprises tetrapropyl ammonium hydroxide, tetramethyl ammonium hydroxide, tetramethyl ammonium bromide, tetrapropyl ammonium bromide, or combinations thereof.
16. The method of claim 1 , wherein the aluminum source comprises aluminum isopropoxide, sodium aluminate, aluminum sulfate, or combinations thereof.
17. The method of claim 1 , wherein the heating is carried out at from 80-150° C.
18. The method of claim 1 , wherein the heating comprises irradiating the mixture with microwave radiation.
19. The method of claim 1 , wherein the alumino-silicate nanoparticles comprise zeolite nanoparticles.
20. The method of claim 1 , wherein the alumino-silicate nanoparticles comprise a crystalline alumino-silicate nanoparticle.
21. The method of claim 1 , wherein the alumino-silicate nanoparticles comprise zeolites having a faujasite structure.
22. A method of making alumino-silicate nanoparticles comprising:
(a) heating a first mixture comprising a silicon source, an aluminum source, a base, an organic agent, and a first solvent to produce a first population of alumino-silicate nanoparticles dispersed in a first supernatant;
(b) separating the first population of inorganic nanoparticles from the first supernatant;
(c) adding a base to the first supernatant to form a second mixture;
(d) heating the second mixture to produce a second population of alumino-silicate nanoparticles dispersed in a second supernatant; and
(e) separating the second population of inorganic nanoparticles from the second supernatant;
wherein step (d) further comprises concentrating the second supernatant to form a concentrated supernatant, and diluting the concentrated supernatant the reform the second supernatant; and
wherein the first population of alumino-silicate nanoparticles and the second population of alumino-silicate nanoparticles each have an average particle size of 100 nm or less.
23. A method of making alumino-silicate nanoparticles comprising:
(a) heating a first mixture comprising a silicon source, an aluminum source, a base, an organic agent, and a first solvent to produce a first population of alumino-silicate nanoparticles dispersed in a first supernatant;
(b) separating the first population of inorganic nanoparticles from the first supernatant;
(c) adding a base to the first supernatant to form a second mixture;
(d) heating the second mixture to produce a second population of alumino-silicate nanoparticles dispersed in a second supernatant; and
(e) separating the second population of inorganic nanoparticles from the second supernatant;
wherein the alumino-silicate nanoparticles comprise zeolites having a faujasite structure; and
wherein the first population of alumino-silicate nanoparticles and the second population of alumino-silicate nanoparticles each have an average particle size of 100 nm or less.