Oleophilic and hydrophobic nanocellulose materials

Abstract

An oleophilic and hydrophobic nanocellulose material is disclosed herein, for nanocellulose sponges and other applications. The oleophilic and hydrophobic nanocellulose material comprises lignin-coated cellulose nanofibrils and/or lignin-coated cellulose nanocrystals. In various embodiments, the nanocellulose material is in the form of a 2D coating or layer, or a 3D object (e.g., foam or aerogel). The nanocellulose material may be disposed onto a scaffold. A process is provided for producing an oleophilic and hydrophobic nanocellulose object, comprising fractionating a biomass feedstock with an acid, a solvent for lignin, and water, to generate cellulose-rich solids and a lignin-containing liquor; mechanically treating the cellulose-rich solids to form cellulose fibrils and/or cellulose crystals; generating a nanocellulose object from the intermediate nanocellulose material; exposing the nanocellulose object to the lignin-containing liquor to allow lignin to deposit onto a surface of the nanocellulose object; and recovering the oleophilic and hydrophobic nanocellulose object.

What is claimed is: 
     
         1 . An oleophilic and hydrophobic nanocellulose material comprising lignin-coated cellulose nanofibrils and/or lignin-coated cellulose nanocrystals, wherein said nanocellulose material is in the form of a coating, a two-dimensional layer, a three-dimensional object, a foam, a sponge, an aerogel, or a combination thereof. 
     
     
         2 . The oleophilic and hydrophobic nanocellulose material of  claim 1 , wherein said material is disposed onto a scaffold material, wherein said scaffold material is selected from the group consisting of cellulose fibers, cellulose fines, biomass fines, lignin particles, wood chips, refined wood particles, pulp, paper, natural fibers, textiles, and combinations thereof. 
     
     
         3 . The oleophilic and hydrophobic nanocellulose material of  claim 1 , wherein said material includes a first lignin phase containing a first degree of sulfonation and a second lignin phase containing a second degree of sulfonation, wherein said first degree of sulfonation is lower than said second degree of sulfonation. 
     
     
         4 . The oleophilic and hydrophobic nanocellulose material of  claim 3 , wherein said first lignin phase is associated with a lignin coating on said lignin-coated cellulose nanofibrils and/or lignin-coated cellulose nanocrystals, and wherein said second lignin phase is associated with sulfonated lignin contained within pores of said material. 
     
     
         5 . A process for producing an oleophilic and hydrophobic nanocellulose material, said process comprising:
 (a) providing a lignocellulosic biomass feedstock;   (b) fractionating said feedstock in the presence of an acid, a solvent for lignin, and water, to generate cellulose-rich solids and a liquid containing hemicellulose and lignin, wherein a portion of said lignin deposits onto a surface of said cellulose-rich solids, thereby rendering said cellulose-rich solids at least partially hydrophobic;   (c) mechanically treating said cellulose-rich solids to form cellulose fibrils and/or cellulose crystals; and   (d) recovering said nanocellulose material as an oleophilic and hydrophobic nanocellulose material.   
     
     
         6 . The process of  claim 5 , wherein said nanocellulose material is in a liquid solution or slurry. 
     
     
         7 . The process of  claim 5 , wherein said nanocellulose material is in the form of a coating, a two-dimensional layer, a three-dimensional object, a foam, a sponge, an aerogel, or a combination thereof. 
     
     
         8 . The process of  claim 5 , wherein said nanocellulose material is disposed onto a scaffold material selected from the group consisting of cellulose fibers, cellulose fines, biomass fines, lignin particles, wood chips, refined wood particles, pulp, paper, natural fibers, textiles, and combinations thereof. 
     
     
         9 . The process of  claim 5 , said process further comprising adsorbing an oil into said nanocellulose material. 
     
     
         10 . A process for producing an oleophilic and hydrophobic nanocellulose object, said process comprising:
 (a) providing a lignocellulosic biomass feedstock;   (b) fractionating said feedstock in the presence of an acid, a solvent for lignin, and water, to generate cellulose-rich solids and a liquid containing hemicellulose and lignin;   (c) mechanically treating said cellulose-rich solids to form an intermediate nanocellulose material comprising cellulose fibrils and/or cellulose crystals;   (d) generating a nanocellulose object from said intermediate nanocellulose material;   (e) exposing said nanocellulose object to a lignin-containing liquor to allow lignin to deposit onto a surface, or within pores, of said nanocellulose object, thereby rendering said nanocellulose object at least partially hydrophobic; and   (f) recovering said nanocellulose object as an oleophilic and hydrophobic nanocellulose object.   
     
     
         11 . The process of  claim 10 , wherein said lignin-containing liquor includes said liquid from step (b). 
     
     
         12 . The process of  claim 10 , wherein said lignin-containing liquor comprises lignosulfonates. 
     
     
         13 . The process of  claim 10 , wherein said lignin-containing liquor comprises non-sulfonated lignin. 
     
     
         14 . The process of  claim 10 , wherein said process comprises flashing, distilling, and/or stripping said lignin-containing liquor after or during step (e), to enhance lignin deposition onto said nanocellulose object. 
     
     
         15 . The process of  claim 10 , wherein during step (b), a portion of said lignin deposits onto a surface of said cellulose-rich solids, thereby rendering said cellulose-rich solids at least partially hydrophobic. 
     
     
         16 . The process of  claim 10 , wherein said nanocellulose object is in the form of a coating, a two-dimensional layer, a three-dimensional object, a foam, a sponge, an aerogel, or a combination thereof. 
     
     
         17 . The process of  claim 10 , wherein said nanocellulose object includes, or is disposed onto, a scaffold material. 
     
     
         18 . The process of  claim 17 , wherein said scaffold material is selected from the group consisting of cellulose fibers, cellulose fines, biomass fines, lignin particles, wood chips, refined wood particles, pulp, paper, natural fibers, textiles, and combinations thereof. 
     
     
         19 . The process of  claim 10 , wherein said nanocellulose object includes a first lignin phase containing a first degree of sulfonation and a second lignin phase containing a second degree of sulfonation, wherein said first degree of sulfonation is lower than said second degree of sulfonation, wherein said first lignin phase is associated with a lignin coating on said lignin-coated cellulose nanofibrils and/or lignin-coated cellulose nanocrystals, and wherein said second lignin phase is associated with sulfonated lignin contained within pores of said nanocellulose object. 
     
     
         20 . The process of  claim 10 , said process further comprising adsorbing an oil into said nanocellulose object.