Hybrid TFC RO membranes with non-metallic additives
A process for preparing a reverse osmosis membrane that includes: (A) providing a polyamine, a polyfunctional acid halide, and a flux increasing additive having the formula Z + B − , where Z + is an easily dissociable cation and B − is a beta-diketonate; (B) combining the polyamine, polyfunctional acid halide, and flux increasing additive on the surface of a porous support membrane; and (C) interfacially polymerizing the polyamine and the polyfunctional acid halide, and flux increasing additive on the surface of the porous support membrane to form a reverse osmosis membrane comprising (i) the porous support membrane and (ii) a discrimination layer comprising a polyamide. The reverse osmosis membrane is characterized by a flux that is greater than the flux of the same membrane prepared in the absence of the flux increasing additive.
1. A composition, comprising:
a flux increasing additive having the formula Z + B − , wherein Z + is an easily dissociable cation selected from among H + and R 1 R 2 R 3 R 4 N + , where R 1 , R 2 , R 3 , and R 4 , each independently is H, a C 1 -C 6 hydrocarbyl group, a benzyl group, or a phenyl group, and B − is a beta-diketonate;
an aqueous phase containing a polar liquid; and
a difunctional or polyfunctional nucleophilic monomer.
2. The composition of claim 1 , wherein Z + has the formula R 1 R 2 R 3 R 4 N + , where R 1 , R 2 , R 3 , and R 4 , each independently is H, a C 1 -C 6 hydrocarbyl group, a benzyl group, or a phenyl group.
3. The composition of claim 2 , wherein R 1 , R 2 , R 3 , and R 4 are ethyl groups.
4. The composition of claim 2 , wherein R 1 , R 2 , and R 3 each is an ethyl group, and R 4 is H.
5. The composition of claim 1 , wherein B − has the formula:
where X and Y, independently, are H, a C 1 -C 6 hydrocarbyl group, a benzyl group, a phenyl group, —OR 5 , or NR 6 R 7 , each optionally substituted with fluorine, and R 5 , R 6 , and R 7 , each independently, is H, a C 1 -C 6 hydrocarbyl group, a benzyl group or a phenyl group.
6. The composition of claim 5 , wherein X and Y each independently is a C 1 -C 6 hydrocarbyl group, a benzyl group, a phenyl group, —OR 5 , or NR 6 R 7 each substituted with fluorine.
7. The composition of claim 5 , wherein X and Y are methyl groups.
8. The composition of claim 5 , wherein X and Y are trifluoromethyl groups.
9. The composition of claim 5 , wherein X and Y are selected so that B − has a 5-carbon or larger carbon framework.
10. The composition of claim 1 , wherein the nucleophilic monomer is a polyamine selected from the group consisting of diaminobenzene, triaminobenzene, m-phenylene diamine, p-phenylene diamine, 1,3,5-diaminobenzoic acid, 2-4-diaminotoluene, 2,4-diaminoanisole, xylylene diamine, ethylene diamine, propylene diamine, piperazine and tris(2-aminoethyl)amine.