Graphene-based membrane and method of producing the same
A graphene-based membrane and a method of producing the same are disclosed. The graphene-based membrane may include a graphene-polymer composite, wherein the graphene-polymer composite may consist of an amine functionalized graphene and a polymer containing an anhydride group as a linker for linking the amine functionalized graphene to the polymer. The graphene-based membrane may be constructed of a single-layer. A method may include reacting a polymer containing an anhydride with an amine functionalized graphene in presence of a solvent to form an intermediate product; and thermal imidizing the intermediate product to form a graphene grafted polymer composite for use in fabricating a graphene-based membrane.
1. A method of producing a single-layer graphene-based membrane from a graphene-polymer composite, the method comprising:
(i) reacting a polymer containing an anhydride group with an amine functionalized graphene in presence of a solvent to form an intermediate product; and
(ii) thermal imidizing the intermediate product to form a graphene grafted polymer composite for use in fabricating graphene-based membrane,
wherein the polymer containing the anhydride group is a poly(acrylonitrile-co-maleic anhydride) and wherein the graphene grafted polymer is a graphene grafted poly(acrylonitrile-co-malemide).
2. The method according to claim 1 , wherein the thermal imidization is carried out by heating the intermediate product at a temperature ranging from 115° C. to 255° C. for a period of 1.5 to 4.5 hours.
3. The method according to claim 1 , wherein the thermal imidization is carried out by heating the intermediate product at 195° C. to 125° C. for 0.5 to 1.5 hours, followed by 180° C. to 220° C. for another 0.5 to 1.5 hours, and 245° C. to 255° C. for yet another 0.5 to 1.5 hours.
4. The method according to claim 1 , wherein the thermal imidization is carried out by heating the intermediate product at 120° C. for 2 hours, followed by 200° C. for 1 hour.
5. The method according to claim 1 , wherein the solvent is a polar aprotic solvent.
6. The method according to claim 5 wherein the solvent is N—N-dimethyl acetamide.
7. The method according to claim 1 , wherein the polymer containing an anhydride group reacts with the amine functionalized graphene at a temperature of 80° C. for 24 hours.
8. The method according to claim 1 , wherein the intermediate product is graphene grafted poly(acrylonitrile-co-maleic acid).
9. The method according to claim 1 , further comprising:
adding the graphene grafted polymer composite to a solution containing polyvinylpyrolidone, N-methyl-2-pyrolidone and diethylene glycol; and
stirring the solution to obtain a homogenous polymeric casting solution for use in fabricating graphene-based membrane.
10. The method according to claim 9 , wherein the casting solution comprises 15 to 40 wt % graphene grafted polymer composite, 2 to 15 wt % polyvinylpyrolidone, 1 to 15 wt % diethylene glycol and 40 to 80 wt % N-methyl-2-pyrolidone.
11. The method according to claim 9 , wherein the casting solution comprises 21 wt % graphene grafted polymer composite, 5 wt % polyvinylpyrolidone, 5 wt % diethylene glycol and 69 wt % N-methyl-2-pyrolidone.
12. The method according to claim 9 , wherein the solution is stirred at a speed of 250 to 350 rpm for at least 24 hours at 80° C.
13. The method according to claim 9 , further comprising:
fabricating the graphene-based membrane using phase inversion method.
14. The method according to claim 13 , wherein the graphene-based membrane is a flat sheet membrane.
15. The method according to claim 1 , further comprising:
adding a second polymer selected from the group consisting of polyethersulfone, polyvinylidene fluoride, polyacrylonitrile, cellulose acetate, polytetrafluoroethylene and polypropylene to the graphene grafted poly(acrylonitrile-co-maleimide) composite to form a mixture;
adding the mixture to a solution comprising polyvinylpyrolidone, N-methyl-2-pyrolidone and diethylene glycol; and
stirring the solution to obtain a homogenous polymeric casting solution for use in fabricating graphene-based membrane.
16. The method according to claim 15 , wherein the second polymer is polyethersulfone.
17. The method according to claim 16 , wherein the casting solution containing the modified polyethersulfone graphene grafted poly(acrylonitrile-co-maleimide) composite comprises 15 to 40 wt % polyethersulfone, 2 to 15 wt % polyvinylpyrolidone, 1 to 15 wt % diethylene glycol, 40 to 80 wt % N-methyl-2-pyrolidone and 1 to 25 wt % graphene grafted poly(acrylonitrile-co-maleimide) composite.
18. The method according to claim 16 , wherein the casting solution containing the modified polyethersulfone graphene grafted poly(acrylonitrile-co-maleimide) composite comprises 21 wt % polyethersulfone, 5 wt % polyvinylpyrolidone, 5 wt % diethylene glycol, 64 wt % N-methyl-2-pyrolidone and 5 wt % graphene grafted poly(acrylonitrile-co-maleimide) composite.
19. The method according to claim 15 , wherein the solution is stirred at a speed of 250 to 350 rpm for at least 24 hours at 80° C.
20. The method according to claim 15 , further comprising:
fabricating the graphene-based membrane using dry-wet spinning method.
21. The method according to claim 20 , wherein the graphene-based membrane is a hollow-fiber membrane.
22. The method according to claim 14 , wherein the graphene-based membrane has an average pore size of 0.04 to 0.10 μm.