FILTRATION MEMBRANES AND METHOD OF MANUFACTURE THEREOF

1 . A filtration membrane comprising:

a porous membrane that comprises a polymer;

a derivatized polydopamine layer disposed on one or both sides of the porous membrane; where the derivatized polydopamine layer is disposed on the porous membrane in the presence of an oxidizing agent.

2 . The filtration membrane of claim 1 , where the polydopamine layer is derivatized with an amine, a thiol, a carboxylic acid, or a combination thereof.

3 . The filtration membrane of claim 1 , where the polymer comprises a polyolefin or a fluoropolymer.

4 . The filtration membrane of claim 1 , where the porous membrane has a nominal pore size of 1 to 5000 nanometers.

5 . The filtration membrane of claim 2 , wherein the amine is dimethylamine.

6 . The filtration membrane of claim 1 , where the polydopamine layer has a thickness of 1 to 100 nm.

7 . The filtration membrane of claim 1 , where the oxidizing agent comprises a periodate, a perchlorate, a persulfate, or a combination thereof.

8 . The filtration membrane of claim 1 , wherein the periodate is sodium metaperiodate.

9 . A method of coating a porous membrane, comprising:

disposing a porous membrane in a solution comprising a dopamine monomer, a buffer, an oxidizing agent and a solvent in a reactor; where the dopamine monomer, the buffer and the oxidizing agent are gradually added to the reactor;

forming a polydopamine layer on the porous membrane; and

derivatizing the polydopamine layer with an amine, a thiol, a carboxylic acid, or a combination thereof.

10 . A method of purifying a liquid comprising:

passing a liquid through a filtration membrane; where the filtration membrane comprises:

a porous membrane;

a derivatized polydopamine layer disposed on one or both sides of the porous membrane; where the derivatized polydopamine layer is disposed on the porous membrane in the presence of an oxidizing agent; and

removing ionic and particulate impurities from the liquid.