Membrane stacks
The present invention discloses a membrane stack comprising a first and second membrane layers, and a spacer layer disposed between said first and second membrane layers, said membrane stack configured such that fluid passes through said membrane stack in a direction substantially perpendicular to the plane of said membrane layers and said spacer layer. The application also discloses a module comprising a membrane as described above, said module having a fluid flow path that is substantially perpendicular to the plane of the major surface of the membrane and spacer layers ins aid membrane stack.
1. A membrane stack, comprising:
first and second membrane layers; and
a spacer layer disposed between said first and second membrane layers; wherein
said membrane stack is configured such that fluid passes through said membrane stack in a direction substantially perpendicular to the plane of said membrane layers and said spacer layer;
the membrane layers and the spacer layer form alternating layers wrapped around a core;
at least one of said membrane layers comprises a macroporous gel-filled membrane layer;
the macroporous gel-filled membrane layer comprises a support member;
the support member comprises a void volume;
said void volume is substantially completely occupied by a macroporous gel; and
the macroporous gel has macropores of average size between about 10 and about 3000 nm.
2. The membrane stack of claim 1 , wherein the macroporous gel-filled membrane layer comprises a responsive macroporous cross-linked gel.
3. The membrane stack according to claim 2 , wherein the responsive macroporous cross-linked gel is responsive to variations in at least one of pH, ionic strength, temperature, light intensity, or electrochemical current.
4. The membrane stack of claim 1 , comprising at least one spacer layer that is formed of a mesh.
5. The membrane stack of claim 1 , wherein said spacer layer(s) has a thickness of about 50 μm to about 500 μm.
6. The membrane stack of claim 1 , wherein said spacer layer(s) have openings having an average diameter of about 50 μm to about 5000 μm.
7. A module comprising a membrane stack according to claim 1 , said module having a fluid flow path that is substantially perpendicular to the plane of the major surface of the membrane and spacer layers in said membrane stack.
8. The module according to claim 7 , wherein said membrane stack is in a spiral wound configuration, or a tubular configuration.
9. A method for separating a substance from a fluid, comprising the step of passing said fluid through a membrane stack according to claim 1 .
10. The membrane stack of claim 1 , wherein the alternating layers are wrapped spirally around the core.
11. The membrane stack of claim 1 , wherein the membrane layers are in contact with the spacer layer.
12. The membrane stack of claim 1 , wherein the alternating layers are not concentric circles around the core.
13. The membrane stack of claim 1 , wherein a single sheet of membrane material or a single sheet of spacer material defines multiple layers in the membrane stack.
14. The membrane stack of claim 1 , wherein the alternating layers are concentric circles around the core.