Selectively permeable graphene oxide membrane

Abstract

Described herein is a graphene material-based membrane that provides selective resistance for solutes or gas while providing water permeability. A selectively permeable membrane comprising graphene oxide, reduced graphene oxide, and also functionalized or crosslinked between the graphene, that provides enhanced salt separation from water or gas permeability resistance, methods for making such membranes, and methods of using the membranes for dehydrating or removing solutes from water are also described.

What is claimed is: 
     
         1 . A membrane comprising:
 a porous substrate; and   a graphene oxide layer comprising an optionally substituted cross-linked graphene oxide in fluid communication with the porous substrate;   wherein the optionally substituted cross-linked graphene oxide comprises an optionally substituted graphene oxide and a cross-linkage represented by the Formula:   
       
         
           
           
               
               
           
         
         wherein R is H, CO 2 H, CO 2 Li, CO 2 Na, or CO 2 K. 
       
     
     
         2 . The membrane of  claim 1 , wherein the cross-linkage is: 
       
         
           
           
               
               
           
         
       
     
     
         3 . The membrane of  claim 1 , wherein the porous substrate comprises a polymer or hollow fibers. 
     
     
         4 . The membrane of  claim 1 , wherein the optionally substituted graphene oxide material comprises platelets. 
     
     
         5 . The membrane of  claim 4 , wherein the platelets have a size that is about 0.05 μm to about 50 μm. 
     
     
         6 . The membrane of  claim 1 , wherein the optionally substituted cross-linked graphene oxide is about 20 atom % to about 90 atom % carbon. 
     
     
         7 . The membrane of  claim 1 , wherein the optionally substituted cross-linked graphene oxide is prepared by reacting an optionally substituted meta-phenylenediamine (MPD) with an optionally substituted graphene oxide (GO), wherein the weight ratio of optionally substituted meta-phenylenediamine to optionally substituted graphene oxide (MPD/GO) is in a range of about 0.1 to about 100. 
     
     
         8 . The membrane of  claim 7 , wherein the weight ratio of the optionally substituted meta-phenylenediamine to the optionally substituted graphene oxide (MPD/GO) is in a range of 1 to 10. 
     
     
         9 . The membrane of  claim 1 , wherein the optionally substituted graphene oxide is a non-functionalized graphene oxide, reduced-graphene oxide, functionalized graphene oxide, functionalized and reduced-graphene oxide, or a combination thereof. 
     
     
         10 . The membrane of  claim 1 , further comprising a salt rejection layer. 
     
     
         11 . The membrane of  claim 10 , wherein the salt rejection layer is disposed on the graphene oxide layer. 
     
     
         12 . The membrane of  claim 10 , wherein the salt rejection layer comprises a polyamide prepared by reacting meta-phenylenediamine with trimesoyl chloride. 
     
     
         13 . The membrane of  claim 1 , wherein the membrane further comprises a protective layer, wherein the protective layer comprises a hydrophilic polymer. 
     
     
         14 . The membrane of  claim 1 , wherein the thickness of the graphene oxide layer is about 5 nm to about 200 nm. 
     
     
         15 . A method for dehydrating an unprocessed fluid, comprising exposing the unprocessed fluid to the membrane of  claim 1 . 
     
     
         16 . A method for removing a solute from an unprocessed solution, comprising exposing the unprocessed solution to the membrane of  claim 1 . 
     
     
         17 . The method of  claim 16 , further comprising passing the unprocessed solution through the membrane. 
     
     
         18 . The method of  claim 17 , wherein passing the unprocessed solution through the membrane is achieved by applying a pressure gradient across the membrane. 
     
     
         19 . A method of making a membrane, comprising:
 (a) resting a solution comprising an optionally substituted graphene oxide and a water soluble cross-linker for about 30 minutes to about 12 hours to create a coating mixture;   (b) applying the coating mixture to a substrate;   (c) repeating step (b) as necessary to achieve the desired thickness or number of layers; and   (d) curing the optionally substituted graphene oxide and water soluble cross-linker upon the substrate at about 50° C. to about 120° C. for about 15 minutes to about 2 hours so that the optionally substituted graphene oxide and the water soluble cross-linker are covalently bonded.   
     
     
         20 . A method of making a membrane from an optionally substituted meta-phenylenediamine cross-linker and an optionally substituted graphene oxide, comprising:
 (a) separately applying to a substrate: 1) an aqueous solution of an optionally substituted graphene oxide and 2) an aqueous solution of an optionally substituted meta-phenylenediamine cross-linker;   (b) repeating step (a) as necessary to achieve the desired thickness or number of layers; and   (c) curing the optionally substituted graphene oxide and cross-linker upon the substrate at about 50° C. to about 120° C. for about 15 minutes to about 2 hours until the optionally substituted graphene oxide and optionally substituted meta-phenylenediamine cross-linker are covalently bonded.