Composition for forming reverse osmosis membrane protection layer, method for preparing reverse osmosis membrane using same, reverse osmosis membrane, and water treatment module

1. A composition for forming a reverse osmosis membrane protective layer, comprising a hydrophilic polymer, glutaraldehyde as a crosslinking agent, and a compound of Chemical Formula 1 having a weight average molecular weight of 500,000 to 700,000:

wherein:

R1 and R2 are the same as or different from each other, and each independently is hydrogen, deuterium, or a substituted or unsubstituted alkyl group;

n is from 10,000 to 20,000; and

wherein the material of Chemical Formula 1 is crosslinked with the hydrophilic polymer via the glutaraldehyde.

2. The composition for forming a reverse osmosis membrane protective layer of claim 1 , wherein R1 and R2 are hydrogen.

3. The composition for forming a reverse osmosis membrane protective layer of claim 1 , wherein the material is present in an amount from 0.3% by weight to 0.5% by weight based on a total weight of the composition for forming a reverse osmosis membrane protective layer.

4. The composition for forming a reverse osmosis membrane protective layer of claim 1 , wherein the hydrophilic polymer is polyvinyl alcohol (PVA).

5. The composition for forming a reverse osmosis membrane protective layer of claim 1 , wherein the hydrophilic polymer is present in an amount from 0.1% by weight to 10% by weight based on a total weight of the composition for forming a reverse osmosis membrane protective layer.

6. The composition for forming a reverse osmosis membrane protective layer of claim 1 , wherein the crosslinking agent is present in an amount from 0.01% by weight to 10% by weight based on a total weight of the composition for forming a reverse osmosis membrane protective layer.

7. A method for preparing a reverse osmosis membrane comprising:

forming a polyamide active layer on a porous support to yield the reverse osmosis membrane; and

on the polyamide active layer forming a protective layer comprising a crosslinked product of a compound of the following Chemical Formula 1 crosslinked with a polyvinyl alcohol, wherein the crosslinked product comprises a reaction product of the polyvinyl alcohol with a crosslinking agent and the compound of Chemical Formula 1 having a weight average molecular weight of 500,000 to 700,000:

wherein:

R1 and R2 are the same as or different from each other, and each independently is hydrogen, deuterium, or a substituted or unsubstituted alkyl group; and

n is from 10,000 to 20,000.

8. A reverse osmosis membrane, comprising:

a porous support;

a polyamide active layer provided on the porous support to yield the reverse osmosis membrane; and

on the polyamide active layer a protective layer comprising a crosslinked product of a compound of the following Chemical Formula 1 crosslinked with a polyvinyl alcohol,

wherein:

the crosslinked product comprises a reaction product of the polyvinyl alcohol with glutaraldehyde as a crosslinking agent and the compound of Chemical Formula 1 having a weight average molecular weight of 500,000 to 700,000, and

the reverse osmosis membrane comprising the protective layer exhibits salt rejection of 99.89% or greater and boron rejection of 93% or greater:

wherein:

R1 and R2 are the same as or different from each other, and each independently is hydrogen, deuterium, or a substituted or unsubstituted alkyl group; and

n is from 10,000 to 20,000.

9. The reverse osmosis membrane of claim 8 , wherein the compound of Chemical Formula 1 is present in an amount from 5% by weight to 20% by weight based on a weight of the protective layer.

10. The reverse osmosis membrane of claim 8 , wherein the polyamide layer in combination with the protective layer has an elastic modulus (Young's modulus) of 4.5 GPa to 10 GPa.

11. A water-treatment module comprising one or more of the reverse osmosis membranes of claim 8 .

12. A water-treatment system comprising one or more of the water-treatment modules of claim 11 .

13. The reverse osmosis membrane of claim 8 , wherein the glutaraldehyde crosslinks the crosslinked product with a surface of the polyamide active layer, and the crosslinked product also is in a physically adsorbed form on the surface of the polyamide layer.