Preparation and use of cellulose nanofiber membrane

Abstract

A filtration membrane comprising cellulose fibres, the membrane having a pore size distribution such that the modal pore diameter is between 10 nm and 25 nm and/or wherein less than 5% of the pore volume comprises pores of greater than 40 nm and having a total porosity greater than 30%.

1 . A laminate filtration membrane comprising a first membrane and one or more support membranes;
 wherein the first membrane comprises a paper formed from cellulose fibres, the cellulose fibres comprising elementary fibrils of diameter greater than 10 nm, the first membrane having a pore size distribution such that the modal pore diameter is between 10 nm and 25 nm and/or wherein less than 5% of the pore volume comprises pores of greater than 40 nm; and   wherein the pore size distribution is determined according to BJH desorption analysis.   
     
     
         2 . The laminate filtration membrane according to  claim 1 , wherein the cellulose fibres are derived from green filamentous algae. 
     
     
         3 . The laminate filtration membrane according to  claim 1 , wherein at least half of the cellulose fibres have a degree of crystallinity greater than 90%. 
     
     
         4 . The laminate filtration membrane according to  claim 1 , wherein at least half of the cellulose fibres are derived from algae Cladophorales and/or algae Siphonocladales. 
     
     
         5 . The laminate filtration membrane according to  claim 1 , wherein at least half of the cellulose comprises elementary fibrils having a diameter greater than 15 nm. 
     
     
         6 . The laminate filtration membrane according to  claim 1 , wherein the modal pore diameter is between 10 nm and 25 nm. 
     
     
         7 . The laminate filtration membrane according to  claim 1 , wherein the first membrane has a porosity of greater than 10%. 
     
     
         8 . The laminate filtration membrane according to  claim 1 , wherein the cellulose fibres are modified by a cross-linking additive. 
     
     
         9 . The laminate filtration membrane according to  claim 1 , wherein it is being used as an air filter. 
     
     
         10 . The laminate filtration membrane according to  claim 1 , wherein at least half of the cellulose fibres are derived from algae  Cladophora  species. 
     
     
         11 . The laminate filtration membrane according to  claim 1 , wherein at least half of the cellulose comprises elementary fibrils having a diameter between 20 nm and 30 nm. 
     
     
         12 . The laminate filtration membrane according to  claim 1 , wherein the modal pore diameter is between 10 nm and 20 nm. 
     
     
         13 . The laminate filtration membrane according to  claim 1 , wherein the first membrane has a porosity of greater than 20%. 
     
     
         14 . The laminate filtration membrane according to  claim 1 , wherein the one or more support membranes may comprise paper, such as paper made from plant-based cellulose. 
     
     
         15 . The laminate filtration membrane according to  claim 1 , wherein the laminate filtration membrane is produced by joining the first membrane and support membrane via direct drying by applying heat and pressure or via using a cross-linking agent(s), wherein the cross-linking agent(s) is/are chosen from formaldehyde/urea, formaldehyde/melamine, formaldehyde/polyethyleimine, polyamide/epichlorhydrine, citric acid and 1,2,3,4-butanetetracarboxylic acid. 
     
     
         16 . The laminate filtration membrane comprising a first membrane and one or more support membranes;
 wherein the first membrane comprises cellulose fibres derived from green filamentous algae, the first membrane having a pore size distribution such that the modal pore diameter is between 10 nm and 25 nm and/or wherein less than 5% of the pore volume comprises pores of greater than 40 nm.   
     
     
         17 . The laminate filtration membrane according to  claim 16 , wherein the cellulose fibres have elementary fibrils of diameter greater than 10 nm. 
     
     
         18 . A laminate filtration membrane comprising:
 a first membrane and one or more support membranes;   wherein the first membrane comprises cellulose fibres, at least half of the cellulose fibres having a degree of crystallinity greater than 90%, the first membrane having a pore size distribution such that the modal pore diameter is between 10 nm and 25 nm and/or wherein less than 5% of the pore volume comprises pores of greater than 40 nm.   
     
     
         19 . The laminate filtration membrane according to  claim 18 , wherein the cellulose fibres are derived from green filamentous algae. 
     
     
         20 . The laminate filtration membrane according to  claim 18 , wherein the cellulose fibres have elementary fibrils of diameter greater than 10 nm. 
     
     
         21 . A method of removing particles from a feed fluid, the method comprising
 passing the feed fluid through a laminate filtration membrane, said laminate filtration membrane comprising:   a first membrane and one or more support membranes;   wherein the first membrane comprises a paper formed from cellulose fibres, the cellulose fibres comprising elementary fibrils of diameter greater than 10 nm, the first membrane having a pore size distribution such that the modal pore diameter is between 10 nm and 25 nm and/or wherein less than 5% of the pore volume comprises pores of greater than 40 nm; and   wherein the pore size distribution is determined according to BJH desorption analysis; and   retaining at least a portion of the particles on the laminate filtration membrane and produce a filtrate containing a lower concentration of the particles than the feed fluid.   
     
     
         22 . The method according to  claim 21 , wherein the particles have a diameter greater than 10 nm. 
     
     
         23 . The method according to  claim 21 , wherein the particles comprise microorganisms such as viruses. 
     
     
         24 . The method according to  claim 21 , wherein the method provides a particle removal probability log reduction value (LRV) of greater than 1. 
     
     
         25 . The method according to  claim 21 , wherein the particles comprise proteins such as protein aggregates and/or protein prion particles. 
     
     
         26 . The method according to  claim 23 , wherein the fluid is passed through the laminate filtration membrane under a pressure differential of approximately 10 to 600 kPa.