Layer-by-layer assembly of graphene oxide membranes via electrostatic interaction and eludication of water and solute transport mechanisms

Abstract

A method for synthesizing a water purification membrane is presented. The method includes stacking a plurality of graphene oxide (GO) nanosheets to create the water purification membrane, the stacking involving layer-by-layer assembly of the plurality of GO nanosheets and forming a plurality of nanochannels between the plurality of GO nanosheets for allowing the flow of a fluid and for rejecting the flow of contaminants. The method further includes cross-linking the plurality of GO nanosheets by 1,3,5-benzenetricarbonyl trichloride on a polydopamine coated polysulfone support.

1 - 9 . (canceled) 
     
     
         10 . A water separation membrane comprising:
 a support substrate; and   a graphene oxide membrane disposed on the support substrate, the graphene oxide membrane including a graphene oxide nanosheet bonded to an adjacent graphene oxide nanosheet.   
     
     
         11 . The water separation membrane of  claim 10 , wherein the graphene oxide nanosheet is covalently coupled to the adjacent graphene oxide nanosheet via a cross-linker. 
     
     
         12 . The water separation membrane of  claim 11 , wherein the cross-linker includes monomers and polymers. 
     
     
         13 . The water separation membrane of  claim 10 , wherein the graphene oxide membrane comprises 5 to 25 layers of electrostatically bonded graphene oxide nanosheets. 
     
     
         14 . The water separation membrane of  claim 13 , wherein a structure, a charge, and a functionality of the graphene oxide nanosheets are configured to be tuned using polyelectrolytes. 
     
     
         15 . The water separation membrane of  claim 13 , further comprising cross-linking the graphene oxide nanosheets by 1,3,5-benzenetricarbonyl trichloride on the support substrate. 
     
     
         16 . The water separation membrane of  claim 10 , wherein the support substrate is a polydopamine coated polysulfone support substrate. 
     
     
         17 . The water separation membrane of  claim 13 , wherein the graphene oxide nanosheets are negatively charged. 
     
     
         18 . The water separation membrane of  claim 13 , further comprising a plurality of nanochannels between the graphene oxide nanosheets for allowing a flow of a fluid and for rejecting a flow of contaminants. 
     
     
         19 . The water separation membrane of  claim 10 , wherein the graphene oxide membrane has a rejection rate of 93-95% of rhodamine-WT. 
     
     
         20 . The water separation membrane of  claim 10 , wherein the graphene oxide membrane has a rejection rate of about 90% of Na 2 SO 4 , as measured with a 0.1 mM Na 2 SO 4  solution. 
     
     
         21 . The water separation membrane of  claim 10 , wherein the support substrate comprises polysulfone. 
     
     
         22 . The water separation membrane of  claim 10 , wherein the support substrate comprises polyacrylonitrile. 
     
     
         23 . The water separation membrane of  claim 11 , wherein the cross-linker is a monomer. 
     
     
         24 . The water separation membrane of  claim 23 , wherein the monomer is ethylenediamine. 
     
     
         25 . The water separation membrane of  claim 11 , wherein the cross-linker is a polymer. 
     
     
         26 . A method for water separation comprising:
 disposing a graphene oxide membrane on a support substrate, wherein the graphene oxide membrane includes a graphene oxide nanosheet; and   bonding the graphene oxide nanosheet to an adjacent graphene oxide nanosheet.   
     
     
         27 . The method of  claim 26 , further comprising:
 wherein bonding the graphene oxide nanosheet to the adjacent graphene oxide nanosheet comprises covalently coupling the graphene oxide nanosheet to the adjacent graphene oxide nanosheet via a cross-linker.   
     
     
         28 . The method of  claim 27 , wherein the cross-linker includes monomers and polymers. 
     
     
         29 . The method of  claim 27 , wherein the graphene oxide membrane comprises 5 to 25 layers of electrostatically bonded graphene oxide nanosheets.