Oil-water separation systems and methods of separating aqueous emulsions

A surface-treated membrane separation system for separating an aqueous emulsion comprising at least two end flow surface-treated membranes in series, housed in a filter assembly, wherein a first surface-treated membrane in the series is oleophobic and comprises:

• (a) a porous substrate;
• and
• (b) an oleophobic coating layer having a thickness of 1 to 20 nm applied to at least one surface of the substrate;
• and
• wherein a second surface-treated membrane in the series is hydrophilic and is spaced from the first membrane by a gap positioned in the direction of flow of the aqueous emulsion whereby the membrane separation system is configured for separating an aqueous emulsion, and wherein the second surface-treated membrane comprises:
• (a′) a porous substrate;
• and
• (b′) a hydrophilic coating layer having a thickness of 1-500 nm applied to at least one surface of the substrate.

A method of separating an aqueous emulsion, comprising:

• (i) contacting the aqueous emulsion with a surface-treated membrane separation system comprising at least two end flow surface-treated membranes in series housed in a filter assembly;
• and
• (ii) allowing water in the emulsion to permeate through the membrane separation system to yield an aqueous product stream, wherein a first surface-treated membrane in the series is oleophobic and comprises:
• (a) a porous substrate;
• and
• (b) an oleophobic coating layer having a thickness of 1 to 20 nm applied to at least one surface of the substrate;
• and
• wherein a second surface-treated membrane in the series is hydrophilic and is spaced from the first membrane by a gap positioned in the direction of flow of the aqueous emulsion, and comprises:
• (a′) a porous substrate;
• and
• (b′) a hydrophilic coating layer having a thickness of 1-500 nm applied to at least one surface of the substrate.