A porous membrane for use in an electroosmotic pump for pumping a fluid by electroosmotic transport, the porous membrane comprising: first and second opposite surfaces and a net fluid flow direction extending in the porous membrane between said opposite surfaces, wherein when a given amount of charge flows through the porous membrane from the first to the second opposite surface more electroosmotic transport of the fluid will occur than when the same amount of charge flows through the porous membrane from the second to the first, opposite surface.

Provided herein are CO.sub.2-selective membranes that can be used to efficiently separate CO.sub.2 and CO. The membranes can be used to produce high-purity CO.sub.2 and CO gas streams from a feed gas stream comprising a mixture of CO.sub.2 and CO (e.g., an exhaust gas stream from a fuel cell, such as a solid oxide fuel cell). In this way, the membranes can be used with a solid oxide fuel cell system to covert CO.sub.2 to CO.

Provided herein are CO.sub.2-selective membranes that can be used to efficiently separate CO.sub.2 and CO. The membranes can be used to produce high-purity CO.sub.2 and CO gas streams from a feed gas stream comprising a mixture of CO.sub.2 and CO (e.g., an exhaust gas stream from a fuel cell, such as a solid oxide fuel cell). In this way, the membranes can be used with a solid oxide fuel cell system to covert CO.sub.2 to CO.

A method of fabricating a gas separation membrane includes providing a coextruded multilayer film that includes a first polymer layer formed of a first polymer material and a second polymer layer formed of a second polymer material, the first polymer material having a first gas permeability. The coextruded multilayer film is axially oriented such that the second polymer layer has a second gas permeability that is greater than the first gas permeability.

A method of making a nanoporous structure comprising a matrix and at least one nanosized pore within the matrix, wherein the method comprises contacting at least a portion of a templated matrix with an acid solution, wherein the templated matrix comprises a matrix that selected from the group consisting of an organic polymer, a sol-based ceramic, an inorganic salt, an organoaluminate, and combinations thereof, and one or more nanosized templates within the matrix, wherein each nanosized template comprises a core that comprises an inorganic oxide, to dissolve at least a portion of the inorganic oxide of at least one of the cores and form the at least one nanosized pore within the matrix thereby forming the nanoporous structure.

A method of making a nanoporous structure comprising a matrix and at least one nanosized pore within the matrix, wherein the method comprises contacting at least a portion of a templated matrix with an acid solution, wherein the templated matrix comprises a matrix that selected from the group consisting of an organic polymer, a sol-based ceramic, an inorganic salt, an organoaluminate, and combinations thereof, and one or more nanosized templates within the matrix, wherein each nanosized template comprises a core that comprises an inorganic oxide, to dissolve at least a portion of the inorganic oxide of at least one of the cores and form the at least one nanosized pore within the matrix thereby forming the nanoporous structure.

A membrane for fluid species transport includes a porous substrate and a selective-transport layer comprising 2-D-material flakes. The porous substrate defines surface pores with dimensions larger than 2 microns, and the selective-transport layer coats the porous substrate and spans across the surface pores. The porous substrate can be contacted with a liquid or coating to fill or coat the surface pores of the porous substrate. Next, a 2-D-material-flake solution is deposited on the porous substrate. Evaporation of solvent from the deposited 2-D-material-flake solution forms the selective-transport layer.

A membrane for fluid species transport includes a porous substrate and a selective-transport layer comprising 2-D-material flakes. The porous substrate defines surface pores with dimensions larger than 2 microns, and the selective-transport layer coats the porous substrate and spans across the surface pores. The porous substrate can be contacted with a liquid or coating to fill or coat the surface pores of the porous substrate. Next, a 2-D-material-flake solution is deposited on the porous substrate. Evaporation of solvent from the deposited 2-D-material-flake solution forms the selective-transport layer.

A process for separating carbon dioxide from a fluid containing carbon dioxide, NO.sub.2, and at least one of oxygen, argon, and nitrogen comprises the steps of separating at least part of the fluid into a carbon dioxide enriched stream, a carbon dioxide depleted stream comprising CO.sub.2 and at least one of oxygen, argon, and nitrogen and a NO.sub.2 enriched stream and recycling said NO.sub.2 enriched stream upstream of the separation step.

The present invention includes a method of cleaning a membrane contactor comprising: connecting a membrane contactor having a first and a second surface, the membrane contactor being in liquid communication with a first and a second liquid circulation loop; rerouting the source of oil-containing liquid from the membrane contactor; draining the oil-containing liquid in contact with the first surface of the membrane contactor via a drain; circulating a cleaning oil over the first surface of the membrane contactor; pumping a collection fluid over the second surface of the membrane contactor; and contacting the oil-containing liquid with the first surface of the membrane contactor under pressure to maximize oil coalescence at the first surface of the membrane contactor while also circulating the collection fluid over the second surface of the membrane contactor to capture the coalesced oil.