Crosslinked cellulosic nanofiltration membranes
The present invention relates to a nanofilter formed by using a porous ultrafiltration membrane as a precursor, and carefully controlling reaction conditions so as to maintain sufficient hydrophilic nature of the membrane while causing the pore structure to close to a nanofilter range (less than 400 Daltons). This produces a solvent stable cellulose nanofiltration membrane capable of operating at satisfactory flux in aqueous solutions, and being low binding to organic biomaterials.
1 ) A hydrophilic nanofiltration membrane comprising crosslinked cellulose capable of operation in polar organic solvents.
2 ) The membrane of claim 1 wherein the polar organic solvent is a dipolar aprotic solvent.
3 ) The membrane of claim 1 wherein the polar organic solvent comprises aqueous mixtures of polar organic solvents.
4 ) The membrane of claim 1 wherein the dipolar aprotic organic solvent comprises aqueous mixtures of dipolar aprotic organic solvents.
5 ) A nanofiltration membrane comprising crosslinked cellulose, capable of operation in dipolar aprotic solvents, said membrane comprising a cellulose ultrafiltration membrane reacted with a multifunctional crosslinking reagent through hydroxyl groups in the anhydroglucose units, under conditions whereby sufficient hydroxyl groups are left unreacted to provide a hydrophilic membrane.
6 ) A hydrophilic nanofiltration membrane comprising crosslinked cellulose capable of operation in dipolar aprotic solvents, suitable for removing organic solutes of greater than about 400 Daltons from organic solvent solutions.
7 ) The membrane of claim 1 further comprising a negative surface charge chemically bonded to its surfaces.
8 ) The membrane of claim 5 further comprising a negative surface charge chemically bonded to its surfaces.
9 ) The membrane of claim 6 further comprising a negative surface charge chemically bonded to its surfaces.
10 ) The membrane of claim 1 further comprising a positive surface charge chemically bonded to its surfaces.
11 ) The membrane of claim 5 further comprising a positive surface charge chemically bonded to its surfaces.
12 ) The membrane of claim 6 further comprising a positive surface charge chemically bonded to its surfaces.
13 ) A method of removing organic solutes from organic aqueous or aqueous-organic solvent solutions comprising passing the solution through a hydrophilic crosslinked cellulose nanofiltration membrane, said membrane comprising a cellulose ultrafiltration membrane capable of operation in dipolar aprotic solvents.
14 ) A method of removing organic solutes from organic aqueous or aqueous-organic solvent solutions comprising passing the solution through a crosslinked cellulose nanofiltration membrane, said membrane comprising a cellulose ultrafiltration membrane capable of operation in dipolar aprotic solvents, reacted with a multifunctional crosslinking reagent through hydroxyl groups in the anhydroglucose units, under conditions whereby sufficient hydroxyl groups are left unreacted to provide a hydrophilic membrane.
15 ) The membrane of claim 1 further comprising the membrane has a support layer.
16 ) The membrane of claim 5 further comprising the membrane has a support layer.
17 ) The membrane of claim 6 further comprising the membrane has a support layer.
18 ) The membrane of claim 1 further comprising the membrane has a support layer capable of operation in dipolar aprotic solvents.
19 ) The membrane of claim 5 further comprising the membrane has a support layer capable of operation in dipolar aprotic solvents.
20 ) The membrane of claim 6 further comprising the membrane has a support layer capable of operation in dipolar aprotic solvents.
21 ) The membrane of claim 1 further comprising the membrane has a support layer formed of a microporous membrane.
22 ) The membrane of claim 5 further comprising the membrane has a support layer formed of a microporous membrane.
23 ) The membrane of claim 6 further comprising the membrane has a support layer formed of a microporous membrane.
24 ) The membrane of claim 1 further comprising the membrane has a support layer formed of a microporous membrane and wherein the microporous membrane is comprised of ultrahigh molecular weight polyethylene.
25 ) The membrane of claim 5 further comprising the membrane has a support layer formed of a microporous membrane and wherein the microporous membrane is comprised of ultrahigh molecular weight polyethylene.
26 ) The membrane of claim 6 further comprising the membrane has a support layer formed of a microporous membrane and wherein the microporous membrane is comprised of ultrahigh molecular weight polyethylene.