Disclosed herein are systems and methods for purifying aqueous solutions. For example, disclosed herein are flexible membrane distillation systems comprising one or more stages stacked on top of each other, wherein each stage comprises: a feedwater layer; a membrane distillation layer; a distillate layer; and a thermally conductive layer. The systems further comprise substantially impermeable top surface, bottom surface, and perimeter. Each feedwater layer is independently receives a portion of a contaminated aqueous solution (a feed solution). Each feedwater layer further receives heat from a heat source to distill at least a portion of the feed solution through the membrane distillation layer, thereby producing a distillate in the distillate layer. Distilling said portion of the feed solution through the membrane distillation layer purifies said portion of the feed solution to produce a purified aqueous solution, which is condensed in the distillate layer to form a condensate.

Disclosed herein are systems and methods for purifying aqueous solutions. For example, disclosed herein are flexible membrane distillation systems comprising one or more stages stacked on top of each other, wherein each stage comprises: a feedwater layer; a membrane distillation layer; a distillate layer; and a thermally conductive layer. The systems further comprise substantially impermeable top surface, bottom surface, and perimeter. Each feedwater layer is independently receives a portion of a contaminated aqueous solution (a feed solution). Each feedwater layer further receives heat from a heat source to distill at least a portion of the feed solution through the membrane distillation layer, thereby producing a distillate in the distillate layer. Distilling said portion of the feed solution through the membrane distillation layer purifies said portion of the feed solution to produce a purified aqueous solution, which is condensed in the distillate layer to form a condensate.

The present invention relates to a separation membrane including a thermoplastic polymer selected from a cellulose ester and a polyamide, in which, when regions obtained by dividing a cross-sectional surface perpendicular to a longitudinal direction of the separation membrane into 5 at an equal interval are defined as regions 1 to 5, all the regions 1 to 5 have a number average pore diameter changing rate a of −0.25 to 0.25, and at least one of the regions 1 to 5 is a region P that satisfies conditions (a) and (b): (a) a value of area average pore diameter D.sub.s/number average pore diameter D.sub.n is 2.50 to 6.00; and (b) a number average W of fine pores that are located at a distance smaller than L.sub.a from a center of respective coarse pores is 10 to 30.

The present invention relates to a separation membrane including a thermoplastic polymer selected from a cellulose ester and a polyamide, in which, when regions obtained by dividing a cross-sectional surface perpendicular to a longitudinal direction of the separation membrane into 5 at an equal interval are defined as regions 1 to 5, all the regions 1 to 5 have a number average pore diameter changing rate a of −0.25 to 0.25, and at least one of the regions 1 to 5 is a region P that satisfies conditions (a) and (b): (a) a value of area average pore diameter D.sub.s/number average pore diameter D.sub.n is 2.50 to 6.00; and (b) a number average W of fine pores that are located at a distance smaller than L.sub.a from a center of respective coarse pores is 10 to 30.

A filter unit includes an inlet for receiving unfiltered water. A first fluid path directs water through a membrane and a filter element to a first outlet. Additionally, a second fluid path directs water across the membrane and to a second outlet.

Provided is a waterproof gas-permeable membrane (1) having higher levels of both gas permeability and waterproofness than conventional ones. The waterproof gas-permeable membrane (1) includes: a non-porous resin film (2) having through holes (21a to 21g) formed to extend through the thickness of the resin film (2); and a liquid-repellent layer (3) formed on a principal surface of the resin film (2) and having openings (31) positioned in register with the through holes (21a to 21g). The through holes (21a to 21g) extend straight and have a diameter of 15 μm or less. The through holes (21a to 21g) are distributed at a hole density of 1×10.sup.3 holes/cm.sup.2 or more and 1×10.sup.9 holes/cm.sup.2 or less in the resin film (2). The through holes (21a to 21g) extend in oblique directions with respect to a direction perpendicular to the principal surface of the resin film (2). The through holes (21a to 21g) that extend in different oblique directions are present together.

Provided is a waterproof gas-permeable membrane (1) having higher levels of both gas permeability and waterproofness than conventional ones. The waterproof gas-permeable membrane (1) includes: a non-porous resin film (2) having through holes (21a to 21g) formed to extend through the thickness of the resin film (2); and a liquid-repellent layer (3) formed on a principal surface of the resin film (2) and having openings (31) positioned in register with the through holes (21a to 21g). The through holes (21a to 21g) extend straight and have a diameter of 15 μm or less. The through holes (21a to 21g) are distributed at a hole density of 1×10.sup.3 holes/cm.sup.2 or more and 1×10.sup.9 holes/cm.sup.2 or less in the resin film (2). The through holes (21a to 21g) extend in oblique directions with respect to a direction perpendicular to the principal surface of the resin film (2). The through holes (21a to 21g) that extend in different oblique directions are present together.

A membrane including a polymer substrate having pore channels and a metal-organic framework disposed on the polymer substrate. Methods of producing the membrane are described. Methods of separating gases using the membrane are also provided.

A membrane including a polymer substrate having pore channels and a metal-organic framework disposed on the polymer substrate. Methods of producing the membrane are described. Methods of separating gases using the membrane are also provided.

A composite porous membrane contains at least one porous base layer and at least one uniaxially stretched coating layer located on at least one side surface of the porous base layer. For example, the composite porous membrane comprises at least one porous base layer and at least one nanofiber-like non-polyolefin polymer porous layer oriented along the transverse stretching direction of the composite porous membrane and located on one or two side surfaces of the porous base layer, or the composite porous membrane comprises a biaxially stretched polypropylene porous base layer and a uniaxially stretched coating layer located on at least one side surface of the porous base layer. The composite porous membrane is coated with a coating solution prior to transversely stretching. The nanofiber-like non-polyolefin polymer porous layer may reduce cracking of the composite porous membrane in the machine direction.